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CDC confirms 13th case of coronavirus in U.S.
The Centers for Disease Control and Prevention announced the number of confirmed cases of the 2019 Novel Coronavirus (2019-nCoV) in the United States has reached 13.
The latest case, announced Feb. 11, 2020, by the CDC, was in a person in California who was previously under federal quarantine because the patient had traveled to Wuhan, China.
The CDC is currently looking into who the patient may have come in contact with to understand the potential for further spread of the coronavirus.
“The contact investigation is ongoing,” CDC principal deputy director Anne Schuchat, MD, said during a Feb. 11 press conference to provide an update on coronavirus containment activities being taken by the CDC.
Dr. Schuchat also addressed issues related to the laboratory test, as the patient in California was initially thought to be negative for the coronavirus.
“With other cases around the country that we are evaluating, we have been doing serial tests to understand whether they are still infectious” and to gather other information about how results change over time, Dr. Schuchat said.
She noted that the CDC does not “have as much information as we would like on the severity of the virus,” noting that there are many cases in China with severe reactions, while the 13 cases in the United States represent a much more mild reaction to the virus so far.
With the latest case in California, she noted that there was “probably a mix-up and the original test wasn’t negative,” although she did not elaborate on what the nature of the mix-up was, stating that was all the information that she had.
In general, Dr. Schuchat touted the actions taken by the CDC and the federal government focused primarily on containing the spread of the virus in the United States, including the implementation of travel advisories, quarantining passengers returning from China, as well as the new test kits that are being distributed by the agency across the nation and around the world. She also mentioned CDC staff are being deployed around the world to monitor the spreading of the disease and highlighted the outreach efforts to keep the public informed.
Dr. Schuchat highlighted the fact that, of the 13 cases in the United States, 11 were with patients that were in Wuhan, and only 2 were because of close contact with a patient, something that she attributed to the actions being taken.
She also noted that cases in the United States have not been as severe as they have been in China, where deaths have been attributed to the coronavirus outbreak. She added that there have been only two deaths outside of mainland China attributed to the coronavirus.
“Some of the steps the CDC has taken have really put us in better shape should widespread transmission occur in the United States,” she said.
Dr. Schuchat also highlighted that the first charter flight of people quarantined after returning from Wuhan have reached the 14-day milestone and should be on their way home beginning today.
The Centers for Disease Control and Prevention announced the number of confirmed cases of the 2019 Novel Coronavirus (2019-nCoV) in the United States has reached 13.
The latest case, announced Feb. 11, 2020, by the CDC, was in a person in California who was previously under federal quarantine because the patient had traveled to Wuhan, China.
The CDC is currently looking into who the patient may have come in contact with to understand the potential for further spread of the coronavirus.
“The contact investigation is ongoing,” CDC principal deputy director Anne Schuchat, MD, said during a Feb. 11 press conference to provide an update on coronavirus containment activities being taken by the CDC.
Dr. Schuchat also addressed issues related to the laboratory test, as the patient in California was initially thought to be negative for the coronavirus.
“With other cases around the country that we are evaluating, we have been doing serial tests to understand whether they are still infectious” and to gather other information about how results change over time, Dr. Schuchat said.
She noted that the CDC does not “have as much information as we would like on the severity of the virus,” noting that there are many cases in China with severe reactions, while the 13 cases in the United States represent a much more mild reaction to the virus so far.
With the latest case in California, she noted that there was “probably a mix-up and the original test wasn’t negative,” although she did not elaborate on what the nature of the mix-up was, stating that was all the information that she had.
In general, Dr. Schuchat touted the actions taken by the CDC and the federal government focused primarily on containing the spread of the virus in the United States, including the implementation of travel advisories, quarantining passengers returning from China, as well as the new test kits that are being distributed by the agency across the nation and around the world. She also mentioned CDC staff are being deployed around the world to monitor the spreading of the disease and highlighted the outreach efforts to keep the public informed.
Dr. Schuchat highlighted the fact that, of the 13 cases in the United States, 11 were with patients that were in Wuhan, and only 2 were because of close contact with a patient, something that she attributed to the actions being taken.
She also noted that cases in the United States have not been as severe as they have been in China, where deaths have been attributed to the coronavirus outbreak. She added that there have been only two deaths outside of mainland China attributed to the coronavirus.
“Some of the steps the CDC has taken have really put us in better shape should widespread transmission occur in the United States,” she said.
Dr. Schuchat also highlighted that the first charter flight of people quarantined after returning from Wuhan have reached the 14-day milestone and should be on their way home beginning today.
The Centers for Disease Control and Prevention announced the number of confirmed cases of the 2019 Novel Coronavirus (2019-nCoV) in the United States has reached 13.
The latest case, announced Feb. 11, 2020, by the CDC, was in a person in California who was previously under federal quarantine because the patient had traveled to Wuhan, China.
The CDC is currently looking into who the patient may have come in contact with to understand the potential for further spread of the coronavirus.
“The contact investigation is ongoing,” CDC principal deputy director Anne Schuchat, MD, said during a Feb. 11 press conference to provide an update on coronavirus containment activities being taken by the CDC.
Dr. Schuchat also addressed issues related to the laboratory test, as the patient in California was initially thought to be negative for the coronavirus.
“With other cases around the country that we are evaluating, we have been doing serial tests to understand whether they are still infectious” and to gather other information about how results change over time, Dr. Schuchat said.
She noted that the CDC does not “have as much information as we would like on the severity of the virus,” noting that there are many cases in China with severe reactions, while the 13 cases in the United States represent a much more mild reaction to the virus so far.
With the latest case in California, she noted that there was “probably a mix-up and the original test wasn’t negative,” although she did not elaborate on what the nature of the mix-up was, stating that was all the information that she had.
In general, Dr. Schuchat touted the actions taken by the CDC and the federal government focused primarily on containing the spread of the virus in the United States, including the implementation of travel advisories, quarantining passengers returning from China, as well as the new test kits that are being distributed by the agency across the nation and around the world. She also mentioned CDC staff are being deployed around the world to monitor the spreading of the disease and highlighted the outreach efforts to keep the public informed.
Dr. Schuchat highlighted the fact that, of the 13 cases in the United States, 11 were with patients that were in Wuhan, and only 2 were because of close contact with a patient, something that she attributed to the actions being taken.
She also noted that cases in the United States have not been as severe as they have been in China, where deaths have been attributed to the coronavirus outbreak. She added that there have been only two deaths outside of mainland China attributed to the coronavirus.
“Some of the steps the CDC has taken have really put us in better shape should widespread transmission occur in the United States,” she said.
Dr. Schuchat also highlighted that the first charter flight of people quarantined after returning from Wuhan have reached the 14-day milestone and should be on their way home beginning today.
Stopping smoking allows healthy lung cells to proliferate
New research results reinforce the benefits of quitting smoking.
Not only does it stop further damage to the lungs, it appears that it also allows new, , say researchers.
The findings were published online in Nature (2020 Jan 29. doi: 10.1038/s41586-020-1961-1).
The team performed whole-genome sequencing on healthy airway cells collected (during a bronchoscopy for clinical indications) from current smokers and ex-smokers, as well as from adult never-smokers and children.
The investigators found, as expected, that the cells from current and ex-smokers had a far higher mutational burden than those of never-smokers and children, including an increased number of “driver” mutations, which increase the potential of cells to become cancerous.
However, they also found that in ex-smokers – but not in current smokers – up to 40% of the cells were near normal, with far less genetic damage and a low risk of developing cancer.
“People who have smoked heavily for 30, 40 or more years often say to me that it’s too late to stop smoking – the damage is already done,” commented senior author Peter J. Campbell, PhD, Cancer Genome Project, Wellcome Trust Sanger Institute, Hinxton, England.
“What is so exciting about our study is that it shows that it’s never too late to quit. Some of the people in our study had smoked more than 15,000 packs of cigarettes over their life, but within a few years of quitting, many of the cells lining their airways showed no evidence of damage from tobacco,” he said. The comments appear in a press release issued by Cancer Research UK, which partly funded the study.
This study has “broadened our understanding of the effects of tobacco smoke on normal epithelial cells in the human lung,” Gerd P. Pfeifer, PhD, at the Center for Epigenetics, Van Andel Institute, Grand Rapids, Michigan, writes in an accompanying comment.
“It has shed light on how the protective effect of smoking cessation plays out at the molecular level in human lung tissue and raises many interesting questions worthy of future investigation,” he added.
‘Important public health message’
Joint senior author Sam M. Janes, PhD, Lungs for Living Research Center, UCL Respiratory, University College London, added that the study has “an important public health message.
“Stopping smoking at any age does not just slow the accumulation of further damage but could reawaken cells unharmed by past lifestyle choices,” he said.
“Further research into this process could help to understand how these cells protect against cancer and could potentially lead to new avenues of research into anticancer therapeutics,” Dr. James added.
In an interview, Dr. Campbell said that the team would next like to try “to find where this reservoir of normal cells hides out while the patient is smoking. We have some ideas from mouse models and we think, by adapting the methods we used in this study, we will be able to test that hypothesis directly.”
He continued: “If we can find this stem cell niche, then we can study the biology of the cells living in there and what makes them expand when a patient stops smoking.
“Once we understand that biology, we can think about therapies to target that population of cells in beneficial ways.”
Dr. Campbell concluded that they are “a long way away yet, but the toolkit exists for getting there.”
Tobacco and mutagenesis
In their article, the team notes that the model explaining how tobacco exposure causes lung cancer centers on the notion that the 60-plus carcinogens in cigarette smoke directly cause mutagenesis, which combines with the indirect effects of inflammation, immune suppression, and infection to lead to cancer.
However, this does not explain why individuals who stop smoking in middle age or earlier “avoid most of the risk of tobacco-associated lung cancer.”
They questioned the relationship between tobacco and mutagenesis. For two people who smoke the same number of cigarettes over their lifetime, the observation that the person with longer duration of cessation has a lower risk for lung cancer is difficult to explain if carcinogenesis is induced exclusively by an increase in the mutational burden, they noted.
To investigate further, the team set out to examine the “landscape” of somatic mutations in normal bronchial epithelium. They recruited 16 individuals: three children, four never-smokers, six ex-smokers, and three current smokers.
All the participants underwent bronchoscopy for clinical indications. Samples of airway epithelium were obtained from biopsies or brushings of main or secondary bronchi.
The researchers performed whole-genome sequencing of 632 colonies derived from single bronchial epithelial cells. In addition, cells from squamous cell carcinoma or carcinoma in situ from three of the patients were sequenced.
Cells show different mutational burdens
The results showed there was “considerable heterogeneity” in mutational burden both between patients and in individual patients.
Moreover, single-base substitutions increased significantly with age, at an estimated rate of 22 per cell per year (P = 10–8). In addition, previous and current smoking substantially increased the substitution burden by an estimated 2,330 per cell in ex-smokers and 5,300 per cell in current smokers.
The team was surprised to find that smoking also increased the variability of the mutational burden from cell to cell, “even within the same individual.”
They calculated that, even between cells from a small biopsy sample of normal airway, the standard deviation in mutational burden was 2,350 per cell in ex-smokers and 2,100 per cell in current smokers, but only 140 per cell in children and 290 per cell in adult never-smokers (P less than 10–16 for within-subject heterogeneity).
Between individuals, the mean substitution burden was 1,200 per cell in ex-smokers, 1,260 per cell in current smokers, and 90 per cell for nonsmokers (P = 10–8 for heterogeneity).
Driver mutations were also more common in individuals who had a history of smoking. In those persons, they were seen in at least 25% of cells vs. 4%-14% of cells from adult never-smokers and none of the cells from children.
It was calculated that current smokers had a 2.1-fold increase in the number of driver mutations per cell in comparison with never-smokers (P = .04).
In addition, the number of driver mutations per cell increased 1.5-fold with every decade of life (P = .004) and twofold for every 5,000 extra somatic mutations per cell (P = .0003).
However, the team also found that some patients among the ex-smokers and current smokers had cells with a near-normal mutational burden, similar to that seen for never-smokers of the equivalent age.
Although these cells were rare in current smokers, their relative frequency was, the team reports, an average fourfold higher in ex-smokers and accounted for between 20% and 40% of all cells studied.
Further analysis showed that these near-normal cells had less damage from tobacco-specific mutational processes than other cells and that they had longer telomeres.
“Two points remain unclear: how these cells have avoided the high rates of mutations that are exhibited by neighbouring cells, and why this particular population of cells expands after smoking cessation,” the team writes.
They argue that the presence of longer telomeres suggests they are “recent descendants of quiescent stem cells,” which have been found in mice but “remain elusive” in human lungs.
“The apparent expansion of the near-normal cells could represent the expected physiology of a two-compartment model in which relatively short-lived proliferative progenitors are slowly replenished from a pool of quiescent stem cells, but the progenitors are more exposed to tobacco carcinogens,” they suggest.
“Only in ex-smokers would the difference in mutagenic environment be sufficient to distinguish newly produced progenitors from long-term occupants of the bronchial epithelial surface,” they add.
However, in his commentary, Dr. Pfeifer highlights that a “potential caveat” of the study is the small number of individuals (n = 16) from whom cells were taken.
In addition, Dr. Pfeifer notes that the “lack of knowledge” about the suggested “long-lived stem cells and information about the longevity of the different cell types in the human lung make it difficult to explain what occurred in the ex-smokers’ cells with few mutations.”
The study was supported by a Cancer Research UK Grand Challenge Award and the Wellcome Trust. Dr. Campbell and Dr. Janes are Wellcome Trust senior clinical fellows. The authors have disclosed no relevant financial relationships.
This article first appeared on Medscape.com.
New research results reinforce the benefits of quitting smoking.
Not only does it stop further damage to the lungs, it appears that it also allows new, , say researchers.
The findings were published online in Nature (2020 Jan 29. doi: 10.1038/s41586-020-1961-1).
The team performed whole-genome sequencing on healthy airway cells collected (during a bronchoscopy for clinical indications) from current smokers and ex-smokers, as well as from adult never-smokers and children.
The investigators found, as expected, that the cells from current and ex-smokers had a far higher mutational burden than those of never-smokers and children, including an increased number of “driver” mutations, which increase the potential of cells to become cancerous.
However, they also found that in ex-smokers – but not in current smokers – up to 40% of the cells were near normal, with far less genetic damage and a low risk of developing cancer.
“People who have smoked heavily for 30, 40 or more years often say to me that it’s too late to stop smoking – the damage is already done,” commented senior author Peter J. Campbell, PhD, Cancer Genome Project, Wellcome Trust Sanger Institute, Hinxton, England.
“What is so exciting about our study is that it shows that it’s never too late to quit. Some of the people in our study had smoked more than 15,000 packs of cigarettes over their life, but within a few years of quitting, many of the cells lining their airways showed no evidence of damage from tobacco,” he said. The comments appear in a press release issued by Cancer Research UK, which partly funded the study.
This study has “broadened our understanding of the effects of tobacco smoke on normal epithelial cells in the human lung,” Gerd P. Pfeifer, PhD, at the Center for Epigenetics, Van Andel Institute, Grand Rapids, Michigan, writes in an accompanying comment.
“It has shed light on how the protective effect of smoking cessation plays out at the molecular level in human lung tissue and raises many interesting questions worthy of future investigation,” he added.
‘Important public health message’
Joint senior author Sam M. Janes, PhD, Lungs for Living Research Center, UCL Respiratory, University College London, added that the study has “an important public health message.
“Stopping smoking at any age does not just slow the accumulation of further damage but could reawaken cells unharmed by past lifestyle choices,” he said.
“Further research into this process could help to understand how these cells protect against cancer and could potentially lead to new avenues of research into anticancer therapeutics,” Dr. James added.
In an interview, Dr. Campbell said that the team would next like to try “to find where this reservoir of normal cells hides out while the patient is smoking. We have some ideas from mouse models and we think, by adapting the methods we used in this study, we will be able to test that hypothesis directly.”
He continued: “If we can find this stem cell niche, then we can study the biology of the cells living in there and what makes them expand when a patient stops smoking.
“Once we understand that biology, we can think about therapies to target that population of cells in beneficial ways.”
Dr. Campbell concluded that they are “a long way away yet, but the toolkit exists for getting there.”
Tobacco and mutagenesis
In their article, the team notes that the model explaining how tobacco exposure causes lung cancer centers on the notion that the 60-plus carcinogens in cigarette smoke directly cause mutagenesis, which combines with the indirect effects of inflammation, immune suppression, and infection to lead to cancer.
However, this does not explain why individuals who stop smoking in middle age or earlier “avoid most of the risk of tobacco-associated lung cancer.”
They questioned the relationship between tobacco and mutagenesis. For two people who smoke the same number of cigarettes over their lifetime, the observation that the person with longer duration of cessation has a lower risk for lung cancer is difficult to explain if carcinogenesis is induced exclusively by an increase in the mutational burden, they noted.
To investigate further, the team set out to examine the “landscape” of somatic mutations in normal bronchial epithelium. They recruited 16 individuals: three children, four never-smokers, six ex-smokers, and three current smokers.
All the participants underwent bronchoscopy for clinical indications. Samples of airway epithelium were obtained from biopsies or brushings of main or secondary bronchi.
The researchers performed whole-genome sequencing of 632 colonies derived from single bronchial epithelial cells. In addition, cells from squamous cell carcinoma or carcinoma in situ from three of the patients were sequenced.
Cells show different mutational burdens
The results showed there was “considerable heterogeneity” in mutational burden both between patients and in individual patients.
Moreover, single-base substitutions increased significantly with age, at an estimated rate of 22 per cell per year (P = 10–8). In addition, previous and current smoking substantially increased the substitution burden by an estimated 2,330 per cell in ex-smokers and 5,300 per cell in current smokers.
The team was surprised to find that smoking also increased the variability of the mutational burden from cell to cell, “even within the same individual.”
They calculated that, even between cells from a small biopsy sample of normal airway, the standard deviation in mutational burden was 2,350 per cell in ex-smokers and 2,100 per cell in current smokers, but only 140 per cell in children and 290 per cell in adult never-smokers (P less than 10–16 for within-subject heterogeneity).
Between individuals, the mean substitution burden was 1,200 per cell in ex-smokers, 1,260 per cell in current smokers, and 90 per cell for nonsmokers (P = 10–8 for heterogeneity).
Driver mutations were also more common in individuals who had a history of smoking. In those persons, they were seen in at least 25% of cells vs. 4%-14% of cells from adult never-smokers and none of the cells from children.
It was calculated that current smokers had a 2.1-fold increase in the number of driver mutations per cell in comparison with never-smokers (P = .04).
In addition, the number of driver mutations per cell increased 1.5-fold with every decade of life (P = .004) and twofold for every 5,000 extra somatic mutations per cell (P = .0003).
However, the team also found that some patients among the ex-smokers and current smokers had cells with a near-normal mutational burden, similar to that seen for never-smokers of the equivalent age.
Although these cells were rare in current smokers, their relative frequency was, the team reports, an average fourfold higher in ex-smokers and accounted for between 20% and 40% of all cells studied.
Further analysis showed that these near-normal cells had less damage from tobacco-specific mutational processes than other cells and that they had longer telomeres.
“Two points remain unclear: how these cells have avoided the high rates of mutations that are exhibited by neighbouring cells, and why this particular population of cells expands after smoking cessation,” the team writes.
They argue that the presence of longer telomeres suggests they are “recent descendants of quiescent stem cells,” which have been found in mice but “remain elusive” in human lungs.
“The apparent expansion of the near-normal cells could represent the expected physiology of a two-compartment model in which relatively short-lived proliferative progenitors are slowly replenished from a pool of quiescent stem cells, but the progenitors are more exposed to tobacco carcinogens,” they suggest.
“Only in ex-smokers would the difference in mutagenic environment be sufficient to distinguish newly produced progenitors from long-term occupants of the bronchial epithelial surface,” they add.
However, in his commentary, Dr. Pfeifer highlights that a “potential caveat” of the study is the small number of individuals (n = 16) from whom cells were taken.
In addition, Dr. Pfeifer notes that the “lack of knowledge” about the suggested “long-lived stem cells and information about the longevity of the different cell types in the human lung make it difficult to explain what occurred in the ex-smokers’ cells with few mutations.”
The study was supported by a Cancer Research UK Grand Challenge Award and the Wellcome Trust. Dr. Campbell and Dr. Janes are Wellcome Trust senior clinical fellows. The authors have disclosed no relevant financial relationships.
This article first appeared on Medscape.com.
New research results reinforce the benefits of quitting smoking.
Not only does it stop further damage to the lungs, it appears that it also allows new, , say researchers.
The findings were published online in Nature (2020 Jan 29. doi: 10.1038/s41586-020-1961-1).
The team performed whole-genome sequencing on healthy airway cells collected (during a bronchoscopy for clinical indications) from current smokers and ex-smokers, as well as from adult never-smokers and children.
The investigators found, as expected, that the cells from current and ex-smokers had a far higher mutational burden than those of never-smokers and children, including an increased number of “driver” mutations, which increase the potential of cells to become cancerous.
However, they also found that in ex-smokers – but not in current smokers – up to 40% of the cells were near normal, with far less genetic damage and a low risk of developing cancer.
“People who have smoked heavily for 30, 40 or more years often say to me that it’s too late to stop smoking – the damage is already done,” commented senior author Peter J. Campbell, PhD, Cancer Genome Project, Wellcome Trust Sanger Institute, Hinxton, England.
“What is so exciting about our study is that it shows that it’s never too late to quit. Some of the people in our study had smoked more than 15,000 packs of cigarettes over their life, but within a few years of quitting, many of the cells lining their airways showed no evidence of damage from tobacco,” he said. The comments appear in a press release issued by Cancer Research UK, which partly funded the study.
This study has “broadened our understanding of the effects of tobacco smoke on normal epithelial cells in the human lung,” Gerd P. Pfeifer, PhD, at the Center for Epigenetics, Van Andel Institute, Grand Rapids, Michigan, writes in an accompanying comment.
“It has shed light on how the protective effect of smoking cessation plays out at the molecular level in human lung tissue and raises many interesting questions worthy of future investigation,” he added.
‘Important public health message’
Joint senior author Sam M. Janes, PhD, Lungs for Living Research Center, UCL Respiratory, University College London, added that the study has “an important public health message.
“Stopping smoking at any age does not just slow the accumulation of further damage but could reawaken cells unharmed by past lifestyle choices,” he said.
“Further research into this process could help to understand how these cells protect against cancer and could potentially lead to new avenues of research into anticancer therapeutics,” Dr. James added.
In an interview, Dr. Campbell said that the team would next like to try “to find where this reservoir of normal cells hides out while the patient is smoking. We have some ideas from mouse models and we think, by adapting the methods we used in this study, we will be able to test that hypothesis directly.”
He continued: “If we can find this stem cell niche, then we can study the biology of the cells living in there and what makes them expand when a patient stops smoking.
“Once we understand that biology, we can think about therapies to target that population of cells in beneficial ways.”
Dr. Campbell concluded that they are “a long way away yet, but the toolkit exists for getting there.”
Tobacco and mutagenesis
In their article, the team notes that the model explaining how tobacco exposure causes lung cancer centers on the notion that the 60-plus carcinogens in cigarette smoke directly cause mutagenesis, which combines with the indirect effects of inflammation, immune suppression, and infection to lead to cancer.
However, this does not explain why individuals who stop smoking in middle age or earlier “avoid most of the risk of tobacco-associated lung cancer.”
They questioned the relationship between tobacco and mutagenesis. For two people who smoke the same number of cigarettes over their lifetime, the observation that the person with longer duration of cessation has a lower risk for lung cancer is difficult to explain if carcinogenesis is induced exclusively by an increase in the mutational burden, they noted.
To investigate further, the team set out to examine the “landscape” of somatic mutations in normal bronchial epithelium. They recruited 16 individuals: three children, four never-smokers, six ex-smokers, and three current smokers.
All the participants underwent bronchoscopy for clinical indications. Samples of airway epithelium were obtained from biopsies or brushings of main or secondary bronchi.
The researchers performed whole-genome sequencing of 632 colonies derived from single bronchial epithelial cells. In addition, cells from squamous cell carcinoma or carcinoma in situ from three of the patients were sequenced.
Cells show different mutational burdens
The results showed there was “considerable heterogeneity” in mutational burden both between patients and in individual patients.
Moreover, single-base substitutions increased significantly with age, at an estimated rate of 22 per cell per year (P = 10–8). In addition, previous and current smoking substantially increased the substitution burden by an estimated 2,330 per cell in ex-smokers and 5,300 per cell in current smokers.
The team was surprised to find that smoking also increased the variability of the mutational burden from cell to cell, “even within the same individual.”
They calculated that, even between cells from a small biopsy sample of normal airway, the standard deviation in mutational burden was 2,350 per cell in ex-smokers and 2,100 per cell in current smokers, but only 140 per cell in children and 290 per cell in adult never-smokers (P less than 10–16 for within-subject heterogeneity).
Between individuals, the mean substitution burden was 1,200 per cell in ex-smokers, 1,260 per cell in current smokers, and 90 per cell for nonsmokers (P = 10–8 for heterogeneity).
Driver mutations were also more common in individuals who had a history of smoking. In those persons, they were seen in at least 25% of cells vs. 4%-14% of cells from adult never-smokers and none of the cells from children.
It was calculated that current smokers had a 2.1-fold increase in the number of driver mutations per cell in comparison with never-smokers (P = .04).
In addition, the number of driver mutations per cell increased 1.5-fold with every decade of life (P = .004) and twofold for every 5,000 extra somatic mutations per cell (P = .0003).
However, the team also found that some patients among the ex-smokers and current smokers had cells with a near-normal mutational burden, similar to that seen for never-smokers of the equivalent age.
Although these cells were rare in current smokers, their relative frequency was, the team reports, an average fourfold higher in ex-smokers and accounted for between 20% and 40% of all cells studied.
Further analysis showed that these near-normal cells had less damage from tobacco-specific mutational processes than other cells and that they had longer telomeres.
“Two points remain unclear: how these cells have avoided the high rates of mutations that are exhibited by neighbouring cells, and why this particular population of cells expands after smoking cessation,” the team writes.
They argue that the presence of longer telomeres suggests they are “recent descendants of quiescent stem cells,” which have been found in mice but “remain elusive” in human lungs.
“The apparent expansion of the near-normal cells could represent the expected physiology of a two-compartment model in which relatively short-lived proliferative progenitors are slowly replenished from a pool of quiescent stem cells, but the progenitors are more exposed to tobacco carcinogens,” they suggest.
“Only in ex-smokers would the difference in mutagenic environment be sufficient to distinguish newly produced progenitors from long-term occupants of the bronchial epithelial surface,” they add.
However, in his commentary, Dr. Pfeifer highlights that a “potential caveat” of the study is the small number of individuals (n = 16) from whom cells were taken.
In addition, Dr. Pfeifer notes that the “lack of knowledge” about the suggested “long-lived stem cells and information about the longevity of the different cell types in the human lung make it difficult to explain what occurred in the ex-smokers’ cells with few mutations.”
The study was supported by a Cancer Research UK Grand Challenge Award and the Wellcome Trust. Dr. Campbell and Dr. Janes are Wellcome Trust senior clinical fellows. The authors have disclosed no relevant financial relationships.
This article first appeared on Medscape.com.
FROM NATURE
Flu activity increases for third straight week
For the second time during the 2019-2020 flu season, activity measures have climbed into noteworthy territory.
The proportion of outpatient visits for influenza-like illness (ILI) reached its highest December level, 7.1%, since 2003 and then dropped for 2 weeks. Three weeks of increases since then, however, have the outpatient-visit rate at 6.7% for the week ending Feb. 1, 2020, the Centers for Disease Control and Prevention reported. The baseline rate for the United States is 2.4%.
That rate of 6.7% is already above the highest rates recorded in eight of the last nine flu seasons, and another increase could mean a second, separate trip above 7.0% in the 2019-2020 season – something that has not occurred since national tracking began in 1997, CDC data show.
Those same data also show that,
Another important measure on the rise, the proportion of respiratory specimens testing positive for influenza, reached a new high for the season, 29.8%, during the week of Feb. 1, the CDC’s influenza division said.
Tests at clinical laboratories also show that predominance is continuing to switch from type B (45.6%) to type A (54.4%), the influenza division noted. Overall predominance for the season, however, continues to favor type B, 59.3% to 40.7%.
The percentage of deaths caused by pneumonia and influenza, which passed the threshold for epidemic of 7.2% back in early January, has been trending downward for the last 3 weeks and was 7.1% as of Feb. 1, according to the influenza division.
ILI-related deaths among children continue to remain high, with a total count of 78 for the season after another 10 deaths were reported during the week ending Feb. 1, the CDC reported. Comparable numbers for the last three seasons are 44 (2018-2019), 97 (2017-2018), and 35 (2016-2017).
The CDC estimates put the total number of ILIs at around 22 million for the season so far, leading to 210,000 hospitalizations. The agency said that it expects to release estimates of vaccine effectiveness later this month.
For the second time during the 2019-2020 flu season, activity measures have climbed into noteworthy territory.
The proportion of outpatient visits for influenza-like illness (ILI) reached its highest December level, 7.1%, since 2003 and then dropped for 2 weeks. Three weeks of increases since then, however, have the outpatient-visit rate at 6.7% for the week ending Feb. 1, 2020, the Centers for Disease Control and Prevention reported. The baseline rate for the United States is 2.4%.
That rate of 6.7% is already above the highest rates recorded in eight of the last nine flu seasons, and another increase could mean a second, separate trip above 7.0% in the 2019-2020 season – something that has not occurred since national tracking began in 1997, CDC data show.
Those same data also show that,
Another important measure on the rise, the proportion of respiratory specimens testing positive for influenza, reached a new high for the season, 29.8%, during the week of Feb. 1, the CDC’s influenza division said.
Tests at clinical laboratories also show that predominance is continuing to switch from type B (45.6%) to type A (54.4%), the influenza division noted. Overall predominance for the season, however, continues to favor type B, 59.3% to 40.7%.
The percentage of deaths caused by pneumonia and influenza, which passed the threshold for epidemic of 7.2% back in early January, has been trending downward for the last 3 weeks and was 7.1% as of Feb. 1, according to the influenza division.
ILI-related deaths among children continue to remain high, with a total count of 78 for the season after another 10 deaths were reported during the week ending Feb. 1, the CDC reported. Comparable numbers for the last three seasons are 44 (2018-2019), 97 (2017-2018), and 35 (2016-2017).
The CDC estimates put the total number of ILIs at around 22 million for the season so far, leading to 210,000 hospitalizations. The agency said that it expects to release estimates of vaccine effectiveness later this month.
For the second time during the 2019-2020 flu season, activity measures have climbed into noteworthy territory.
The proportion of outpatient visits for influenza-like illness (ILI) reached its highest December level, 7.1%, since 2003 and then dropped for 2 weeks. Three weeks of increases since then, however, have the outpatient-visit rate at 6.7% for the week ending Feb. 1, 2020, the Centers for Disease Control and Prevention reported. The baseline rate for the United States is 2.4%.
That rate of 6.7% is already above the highest rates recorded in eight of the last nine flu seasons, and another increase could mean a second, separate trip above 7.0% in the 2019-2020 season – something that has not occurred since national tracking began in 1997, CDC data show.
Those same data also show that,
Another important measure on the rise, the proportion of respiratory specimens testing positive for influenza, reached a new high for the season, 29.8%, during the week of Feb. 1, the CDC’s influenza division said.
Tests at clinical laboratories also show that predominance is continuing to switch from type B (45.6%) to type A (54.4%), the influenza division noted. Overall predominance for the season, however, continues to favor type B, 59.3% to 40.7%.
The percentage of deaths caused by pneumonia and influenza, which passed the threshold for epidemic of 7.2% back in early January, has been trending downward for the last 3 weeks and was 7.1% as of Feb. 1, according to the influenza division.
ILI-related deaths among children continue to remain high, with a total count of 78 for the season after another 10 deaths were reported during the week ending Feb. 1, the CDC reported. Comparable numbers for the last three seasons are 44 (2018-2019), 97 (2017-2018), and 35 (2016-2017).
The CDC estimates put the total number of ILIs at around 22 million for the season so far, leading to 210,000 hospitalizations. The agency said that it expects to release estimates of vaccine effectiveness later this month.
Remdesivir under study as treatment for novel coronavirus
“What they’re looking at is the effect of this drug -- either the drug plus standard of care versus standard of care alone,” Anthony S. Fauci, MD, reported Feb. 7 during a press briefing held by members of President Trump’s Coronavirus Task Force. “I think pretty soon we are going to get a definitive answer, whether one of these among several drugs works.”
Dr. Fauci, director of the National Institute of Allergy and Infectious Diseases, added that several organizations and individual investigators are developing vaccines for 2019-nCoV. In one such effort, the National Institutes of Health is working with Moderna Inc. to develop a vaccine built on a messenger RNA platform. “One of the first steps is to successfully get that [novel coronavirus] gene and insert it into the messenger RNA platform successfully and allow it to express proteins,” Dr. Fauci explained. “We’ve succeeded in that. The next [step] is to put it in a mouse animal model to induce immunogenicity, and to get the company to make [gold nanoparticle] products. All of those have been successfully implemented. There have been no glitches so far. If that continues, we will be in Phase 1 trials in people within the next two-and-a-half months.”
In another development on the same day, Robert R. Redfield, MD, director of the Centers for Disease Control and Prevention, announced that Heath & Human Services issued an interim final rule to amend foreign quarantine regulations in the wake of the public health threat posed by the 2019-nCoV. “This will enable CDC to collect certain contact information data regarding airline passengers and crew when they arrive from other countries. . .and may be exposed to communicable disease,” Dr. Redfield said. “This action is part of our multi-layered approach to the U.S. response and demonstrates our commitment to take all necessary actions to protect the American people.”
According to Alex Azar, secretary of Health and Human Services, and chair of President Trump’s Coronavirus Task Force, there are 12 confirmed cases of the novel coronavirus in the United States, including two cases of transmission to people who had not recently been in China. “Although the virus represents a potentially very serious public health threat, and we expect to continue seeing more cases here, the immediate risk to the American public is low at this time,” Mr. Azar said. “We are working as quickly as possible on the many unanswered questions about this virus. That includes exactly how it spreads, how deadly it is, whether it’s commonly transmitted by patients who are not yet displaying symptoms, and other issues.”
“What they’re looking at is the effect of this drug -- either the drug plus standard of care versus standard of care alone,” Anthony S. Fauci, MD, reported Feb. 7 during a press briefing held by members of President Trump’s Coronavirus Task Force. “I think pretty soon we are going to get a definitive answer, whether one of these among several drugs works.”
Dr. Fauci, director of the National Institute of Allergy and Infectious Diseases, added that several organizations and individual investigators are developing vaccines for 2019-nCoV. In one such effort, the National Institutes of Health is working with Moderna Inc. to develop a vaccine built on a messenger RNA platform. “One of the first steps is to successfully get that [novel coronavirus] gene and insert it into the messenger RNA platform successfully and allow it to express proteins,” Dr. Fauci explained. “We’ve succeeded in that. The next [step] is to put it in a mouse animal model to induce immunogenicity, and to get the company to make [gold nanoparticle] products. All of those have been successfully implemented. There have been no glitches so far. If that continues, we will be in Phase 1 trials in people within the next two-and-a-half months.”
In another development on the same day, Robert R. Redfield, MD, director of the Centers for Disease Control and Prevention, announced that Heath & Human Services issued an interim final rule to amend foreign quarantine regulations in the wake of the public health threat posed by the 2019-nCoV. “This will enable CDC to collect certain contact information data regarding airline passengers and crew when they arrive from other countries. . .and may be exposed to communicable disease,” Dr. Redfield said. “This action is part of our multi-layered approach to the U.S. response and demonstrates our commitment to take all necessary actions to protect the American people.”
According to Alex Azar, secretary of Health and Human Services, and chair of President Trump’s Coronavirus Task Force, there are 12 confirmed cases of the novel coronavirus in the United States, including two cases of transmission to people who had not recently been in China. “Although the virus represents a potentially very serious public health threat, and we expect to continue seeing more cases here, the immediate risk to the American public is low at this time,” Mr. Azar said. “We are working as quickly as possible on the many unanswered questions about this virus. That includes exactly how it spreads, how deadly it is, whether it’s commonly transmitted by patients who are not yet displaying symptoms, and other issues.”
“What they’re looking at is the effect of this drug -- either the drug plus standard of care versus standard of care alone,” Anthony S. Fauci, MD, reported Feb. 7 during a press briefing held by members of President Trump’s Coronavirus Task Force. “I think pretty soon we are going to get a definitive answer, whether one of these among several drugs works.”
Dr. Fauci, director of the National Institute of Allergy and Infectious Diseases, added that several organizations and individual investigators are developing vaccines for 2019-nCoV. In one such effort, the National Institutes of Health is working with Moderna Inc. to develop a vaccine built on a messenger RNA platform. “One of the first steps is to successfully get that [novel coronavirus] gene and insert it into the messenger RNA platform successfully and allow it to express proteins,” Dr. Fauci explained. “We’ve succeeded in that. The next [step] is to put it in a mouse animal model to induce immunogenicity, and to get the company to make [gold nanoparticle] products. All of those have been successfully implemented. There have been no glitches so far. If that continues, we will be in Phase 1 trials in people within the next two-and-a-half months.”
In another development on the same day, Robert R. Redfield, MD, director of the Centers for Disease Control and Prevention, announced that Heath & Human Services issued an interim final rule to amend foreign quarantine regulations in the wake of the public health threat posed by the 2019-nCoV. “This will enable CDC to collect certain contact information data regarding airline passengers and crew when they arrive from other countries. . .and may be exposed to communicable disease,” Dr. Redfield said. “This action is part of our multi-layered approach to the U.S. response and demonstrates our commitment to take all necessary actions to protect the American people.”
According to Alex Azar, secretary of Health and Human Services, and chair of President Trump’s Coronavirus Task Force, there are 12 confirmed cases of the novel coronavirus in the United States, including two cases of transmission to people who had not recently been in China. “Although the virus represents a potentially very serious public health threat, and we expect to continue seeing more cases here, the immediate risk to the American public is low at this time,” Mr. Azar said. “We are working as quickly as possible on the many unanswered questions about this virus. That includes exactly how it spreads, how deadly it is, whether it’s commonly transmitted by patients who are not yet displaying symptoms, and other issues.”
Report chastises government for allowing flavored e-cigarettes
according to a report on federal and state policies.
In its annual “State of Tobacco Control” report, the American Lung Association called out the federal government for issuing “inadequate guidance on flavored e-cigarettes that leaves thousands of flavored e-cigarettes on the market.” The organization urged Congress and the Food and Drug Administration “to eliminate all flavored tobacco products from the marketplace, including menthol cigarettes, flavored cigars, and e-cigarettes,” in 2020.
“Flavored tobacco products cause kids to become hooked, and now more than one in four teens (27.5%) are vaping, a staggering 135% increase over the past 2 years,” the association wrote in a news release. Federal guidance on Jan. 2, 2020, permits the sale of flavored e-cigarettes that do not use cartridges. This guidance represented a reversal after officials said in a prior announcement that regulators would “clear the market” of flavored e-cigarettes.
Graphic warning labels
The report also asked the FDA to reject product marketing applications that fail to meet public health standards, calls on the U.S. Department of Health & Human Services to “clarify and ensure that all tobacco users have access to a comprehensive tobacco cessation benefit,” and urges Congress to increase federal funding for the Centers for Disease Control and Prevention’s Office on Smoking and Health to help stop youth e-cigarette use.
“Raising the federal minimum age of sale to 21, which took effect immediately on Dec. 30, was an important first step forward,” the report says. “The American Lung Association successfully advocated for the legislation to be comprehensive and to close state exemptions, such as for military personnel, while also not limiting states from pursuing stronger protections. Additional rules from FDA to provide guidance on the law’s implementation are forthcoming.”
The FDA is expected to release graphic warning labels for cigarette packs in March. After legal setbacks to the Tobacco Control Act of 2009, which required the FDA to ensure all cigarette packs had graphic warning labels by 2011, a judgment “compels FDA to release final graphic warnings by March 15, 2020, with the warning labels appearing on all cigarette packs by June of 2021,” the American Lung Association report said.
“While the American Lung Association recognizes the federal government with an A grade for passage of a strong federal Tobacco 21 law [raising the minimum age of purchase], it also earns an F for its failure to comprehensively oversee tobacco products,” said Harold P. Wimmer, national president and CEO of the American Lung Association, in the news release. “Without meaningful actions by the federal government, the health and the future of our nation’s children are being compromised.”
The federal government received an F for its tobacco tax policies, a D for cessation coverage, and an A for its mass media campaigns, “Tips from Former Smokers” and “The Real Cost.”
Grading states
In addition, the report graded each state and the District of Columbia in terms of funding for tobacco prevention programs, strength of smoke-free workplace laws, level of state tobacco taxes, and coverage of and access to services to quit tobacco. None scored all A’s, but California, the District of Columbia, Maine, New York, and Vermont ranked the highest. Alabama, Mississippi, and North Carolina, on the other hand, received all F’s.
In November, Massachusetts became the first state to prohibit the sale of flavored tobacco products, including menthol cigarettes, and more states should follow suit, according to the association.
according to a report on federal and state policies.
In its annual “State of Tobacco Control” report, the American Lung Association called out the federal government for issuing “inadequate guidance on flavored e-cigarettes that leaves thousands of flavored e-cigarettes on the market.” The organization urged Congress and the Food and Drug Administration “to eliminate all flavored tobacco products from the marketplace, including menthol cigarettes, flavored cigars, and e-cigarettes,” in 2020.
“Flavored tobacco products cause kids to become hooked, and now more than one in four teens (27.5%) are vaping, a staggering 135% increase over the past 2 years,” the association wrote in a news release. Federal guidance on Jan. 2, 2020, permits the sale of flavored e-cigarettes that do not use cartridges. This guidance represented a reversal after officials said in a prior announcement that regulators would “clear the market” of flavored e-cigarettes.
Graphic warning labels
The report also asked the FDA to reject product marketing applications that fail to meet public health standards, calls on the U.S. Department of Health & Human Services to “clarify and ensure that all tobacco users have access to a comprehensive tobacco cessation benefit,” and urges Congress to increase federal funding for the Centers for Disease Control and Prevention’s Office on Smoking and Health to help stop youth e-cigarette use.
“Raising the federal minimum age of sale to 21, which took effect immediately on Dec. 30, was an important first step forward,” the report says. “The American Lung Association successfully advocated for the legislation to be comprehensive and to close state exemptions, such as for military personnel, while also not limiting states from pursuing stronger protections. Additional rules from FDA to provide guidance on the law’s implementation are forthcoming.”
The FDA is expected to release graphic warning labels for cigarette packs in March. After legal setbacks to the Tobacco Control Act of 2009, which required the FDA to ensure all cigarette packs had graphic warning labels by 2011, a judgment “compels FDA to release final graphic warnings by March 15, 2020, with the warning labels appearing on all cigarette packs by June of 2021,” the American Lung Association report said.
“While the American Lung Association recognizes the federal government with an A grade for passage of a strong federal Tobacco 21 law [raising the minimum age of purchase], it also earns an F for its failure to comprehensively oversee tobacco products,” said Harold P. Wimmer, national president and CEO of the American Lung Association, in the news release. “Without meaningful actions by the federal government, the health and the future of our nation’s children are being compromised.”
The federal government received an F for its tobacco tax policies, a D for cessation coverage, and an A for its mass media campaigns, “Tips from Former Smokers” and “The Real Cost.”
Grading states
In addition, the report graded each state and the District of Columbia in terms of funding for tobacco prevention programs, strength of smoke-free workplace laws, level of state tobacco taxes, and coverage of and access to services to quit tobacco. None scored all A’s, but California, the District of Columbia, Maine, New York, and Vermont ranked the highest. Alabama, Mississippi, and North Carolina, on the other hand, received all F’s.
In November, Massachusetts became the first state to prohibit the sale of flavored tobacco products, including menthol cigarettes, and more states should follow suit, according to the association.
according to a report on federal and state policies.
In its annual “State of Tobacco Control” report, the American Lung Association called out the federal government for issuing “inadequate guidance on flavored e-cigarettes that leaves thousands of flavored e-cigarettes on the market.” The organization urged Congress and the Food and Drug Administration “to eliminate all flavored tobacco products from the marketplace, including menthol cigarettes, flavored cigars, and e-cigarettes,” in 2020.
“Flavored tobacco products cause kids to become hooked, and now more than one in four teens (27.5%) are vaping, a staggering 135% increase over the past 2 years,” the association wrote in a news release. Federal guidance on Jan. 2, 2020, permits the sale of flavored e-cigarettes that do not use cartridges. This guidance represented a reversal after officials said in a prior announcement that regulators would “clear the market” of flavored e-cigarettes.
Graphic warning labels
The report also asked the FDA to reject product marketing applications that fail to meet public health standards, calls on the U.S. Department of Health & Human Services to “clarify and ensure that all tobacco users have access to a comprehensive tobacco cessation benefit,” and urges Congress to increase federal funding for the Centers for Disease Control and Prevention’s Office on Smoking and Health to help stop youth e-cigarette use.
“Raising the federal minimum age of sale to 21, which took effect immediately on Dec. 30, was an important first step forward,” the report says. “The American Lung Association successfully advocated for the legislation to be comprehensive and to close state exemptions, such as for military personnel, while also not limiting states from pursuing stronger protections. Additional rules from FDA to provide guidance on the law’s implementation are forthcoming.”
The FDA is expected to release graphic warning labels for cigarette packs in March. After legal setbacks to the Tobacco Control Act of 2009, which required the FDA to ensure all cigarette packs had graphic warning labels by 2011, a judgment “compels FDA to release final graphic warnings by March 15, 2020, with the warning labels appearing on all cigarette packs by June of 2021,” the American Lung Association report said.
“While the American Lung Association recognizes the federal government with an A grade for passage of a strong federal Tobacco 21 law [raising the minimum age of purchase], it also earns an F for its failure to comprehensively oversee tobacco products,” said Harold P. Wimmer, national president and CEO of the American Lung Association, in the news release. “Without meaningful actions by the federal government, the health and the future of our nation’s children are being compromised.”
The federal government received an F for its tobacco tax policies, a D for cessation coverage, and an A for its mass media campaigns, “Tips from Former Smokers” and “The Real Cost.”
Grading states
In addition, the report graded each state and the District of Columbia in terms of funding for tobacco prevention programs, strength of smoke-free workplace laws, level of state tobacco taxes, and coverage of and access to services to quit tobacco. None scored all A’s, but California, the District of Columbia, Maine, New York, and Vermont ranked the highest. Alabama, Mississippi, and North Carolina, on the other hand, received all F’s.
In November, Massachusetts became the first state to prohibit the sale of flavored tobacco products, including menthol cigarettes, and more states should follow suit, according to the association.
CDC begins coronavirus diagnostic test kit distribution; new case confirmed in Wisconsin
The Centers for Disease Control and Prevention and the Wisconsin Department of Health Services confirmed a new case of the 2019 Novel Coronavirus (2019-nCoV) on Feb. 5, 2020, bringing the total number of cases in the United States to 12.*
Earlier in the day, Nancy Messonnier, MD, director of the CDC National Center for Immunization and Respiratory Diseases, told reporters that 206 individuals under investigation had tested negative for infection with the novel virus and that tests were pending on another 76 individuals.
The agency also announced during a press briefing call that diagnostic test kits will begin shipping on Feb. 5, less than 24 hours after receiving an emergency use authorization from the Food and Drug Administration. Full information is available in an article published in the Morbidity and Mortality Weekly Report.
The emergency use authorization will allow for broader use of the CDC’s 2019-nCoV Real Time RT-PCR Diagnostic Panel, which to date has been limited for use at CDC laboratories. Under the emergency use authorization, the diagnostic kit is authorized for patients who meed the CDC criteria for 2019-nCoV testing. The diagnostic test is a reverse transcriptase polymerase chain reaction test that provides presumptive detection of 2019-nCoV from respiratory secretions, such as nasal or oral swabs. A positive test indicates likely infection, although a negative test does not preclude infection and should not be the sole determination for patient management decisions.
“Today, the test kits will start shipping to over 100 U.S. public health labs,” she said. “Each of these labs is required to perform international verification for [Clinical Laboratory Improvement Amendments] compliance prior to reporting out. This process is expected to take a few days.”
Dr. Messonnier said that 200 test kits will be distributed to domestic labs and another 200 test kits will go to select international labs. Each kit can perform diagnostics on 700-800 patient samples.
“What that means is that, by the start of next week, we expect there to be much enhanced capacity for laboratory testing closer to our patients,” she said, adding that additional test kits are being produced and will be available for ordering in the future. Each laboratory that places an order will receive one test kit.
“Distribution of these tests will improve the global capacity to detect and respond to this new virus,” Dr. Messonnier said. “Availability of this test is a starting place for greater commercial availability of diagnostic testing for nCoV.”
The CDC also said that the next batch of passengers arriving from Wuhan, China, will be arriving in one of four locations: Travis Air Force Base, Fairfield, Calif.; Marine Corps Air Station Miramar, San Diego; Lackland Air Force Base, San Antonio; and Eppley Airfield, Omaha, Neb. Passengers will be quarantined for up to 14 days from the day the flight left Wuhan and medical care will be provided if needed.
“We do not believe these people pose a threat to the communities where they are being housed as we are taking measures to minimize any contact,” she said, adding that confirmed infections are expected among these and other returning travelers.
Dr. Messonnier warned that the quarantine measures “may not catch every single returning traveler returning with novel coronavirus, given the nature of this virus and how it is spreading. But if we can catch the majority of them, that will slow the entry of this virus into the United States.”
*This story was updated on 02/05/2020.
The Centers for Disease Control and Prevention and the Wisconsin Department of Health Services confirmed a new case of the 2019 Novel Coronavirus (2019-nCoV) on Feb. 5, 2020, bringing the total number of cases in the United States to 12.*
Earlier in the day, Nancy Messonnier, MD, director of the CDC National Center for Immunization and Respiratory Diseases, told reporters that 206 individuals under investigation had tested negative for infection with the novel virus and that tests were pending on another 76 individuals.
The agency also announced during a press briefing call that diagnostic test kits will begin shipping on Feb. 5, less than 24 hours after receiving an emergency use authorization from the Food and Drug Administration. Full information is available in an article published in the Morbidity and Mortality Weekly Report.
The emergency use authorization will allow for broader use of the CDC’s 2019-nCoV Real Time RT-PCR Diagnostic Panel, which to date has been limited for use at CDC laboratories. Under the emergency use authorization, the diagnostic kit is authorized for patients who meed the CDC criteria for 2019-nCoV testing. The diagnostic test is a reverse transcriptase polymerase chain reaction test that provides presumptive detection of 2019-nCoV from respiratory secretions, such as nasal or oral swabs. A positive test indicates likely infection, although a negative test does not preclude infection and should not be the sole determination for patient management decisions.
“Today, the test kits will start shipping to over 100 U.S. public health labs,” she said. “Each of these labs is required to perform international verification for [Clinical Laboratory Improvement Amendments] compliance prior to reporting out. This process is expected to take a few days.”
Dr. Messonnier said that 200 test kits will be distributed to domestic labs and another 200 test kits will go to select international labs. Each kit can perform diagnostics on 700-800 patient samples.
“What that means is that, by the start of next week, we expect there to be much enhanced capacity for laboratory testing closer to our patients,” she said, adding that additional test kits are being produced and will be available for ordering in the future. Each laboratory that places an order will receive one test kit.
“Distribution of these tests will improve the global capacity to detect and respond to this new virus,” Dr. Messonnier said. “Availability of this test is a starting place for greater commercial availability of diagnostic testing for nCoV.”
The CDC also said that the next batch of passengers arriving from Wuhan, China, will be arriving in one of four locations: Travis Air Force Base, Fairfield, Calif.; Marine Corps Air Station Miramar, San Diego; Lackland Air Force Base, San Antonio; and Eppley Airfield, Omaha, Neb. Passengers will be quarantined for up to 14 days from the day the flight left Wuhan and medical care will be provided if needed.
“We do not believe these people pose a threat to the communities where they are being housed as we are taking measures to minimize any contact,” she said, adding that confirmed infections are expected among these and other returning travelers.
Dr. Messonnier warned that the quarantine measures “may not catch every single returning traveler returning with novel coronavirus, given the nature of this virus and how it is spreading. But if we can catch the majority of them, that will slow the entry of this virus into the United States.”
*This story was updated on 02/05/2020.
The Centers for Disease Control and Prevention and the Wisconsin Department of Health Services confirmed a new case of the 2019 Novel Coronavirus (2019-nCoV) on Feb. 5, 2020, bringing the total number of cases in the United States to 12.*
Earlier in the day, Nancy Messonnier, MD, director of the CDC National Center for Immunization and Respiratory Diseases, told reporters that 206 individuals under investigation had tested negative for infection with the novel virus and that tests were pending on another 76 individuals.
The agency also announced during a press briefing call that diagnostic test kits will begin shipping on Feb. 5, less than 24 hours after receiving an emergency use authorization from the Food and Drug Administration. Full information is available in an article published in the Morbidity and Mortality Weekly Report.
The emergency use authorization will allow for broader use of the CDC’s 2019-nCoV Real Time RT-PCR Diagnostic Panel, which to date has been limited for use at CDC laboratories. Under the emergency use authorization, the diagnostic kit is authorized for patients who meed the CDC criteria for 2019-nCoV testing. The diagnostic test is a reverse transcriptase polymerase chain reaction test that provides presumptive detection of 2019-nCoV from respiratory secretions, such as nasal or oral swabs. A positive test indicates likely infection, although a negative test does not preclude infection and should not be the sole determination for patient management decisions.
“Today, the test kits will start shipping to over 100 U.S. public health labs,” she said. “Each of these labs is required to perform international verification for [Clinical Laboratory Improvement Amendments] compliance prior to reporting out. This process is expected to take a few days.”
Dr. Messonnier said that 200 test kits will be distributed to domestic labs and another 200 test kits will go to select international labs. Each kit can perform diagnostics on 700-800 patient samples.
“What that means is that, by the start of next week, we expect there to be much enhanced capacity for laboratory testing closer to our patients,” she said, adding that additional test kits are being produced and will be available for ordering in the future. Each laboratory that places an order will receive one test kit.
“Distribution of these tests will improve the global capacity to detect and respond to this new virus,” Dr. Messonnier said. “Availability of this test is a starting place for greater commercial availability of diagnostic testing for nCoV.”
The CDC also said that the next batch of passengers arriving from Wuhan, China, will be arriving in one of four locations: Travis Air Force Base, Fairfield, Calif.; Marine Corps Air Station Miramar, San Diego; Lackland Air Force Base, San Antonio; and Eppley Airfield, Omaha, Neb. Passengers will be quarantined for up to 14 days from the day the flight left Wuhan and medical care will be provided if needed.
“We do not believe these people pose a threat to the communities where they are being housed as we are taking measures to minimize any contact,” she said, adding that confirmed infections are expected among these and other returning travelers.
Dr. Messonnier warned that the quarantine measures “may not catch every single returning traveler returning with novel coronavirus, given the nature of this virus and how it is spreading. But if we can catch the majority of them, that will slow the entry of this virus into the United States.”
*This story was updated on 02/05/2020.
The 2019 novel coronavirus: Case review IDs clinical characteristics
A group of physicians in Wuhan, China, who are treating patients with the 2019 novel coronavirus have gone the extra mile to share their clinical experiences with colleagues around the world.
Nanshan Chen, MD, of Jinyintan Hospital, Wuhan, and his team conducted a retrospective study on 99 cases and, in very short order, published their initial findings in the Lancet online on Jan. 29. These findings could guide action in other cases and help clinicians all over the world create treatment plans for patients of the 2019-nCoV.
The findings show that and characteristics of those with fatal infections align with the MuLBSTA score – an early warning model for predicting viral pneumonia–related mortality, according to a case review.
Of 99 patients who presented with 2019-nCoV pneumonia at Jinyintan Hospital between Jan. 1 and Jan. 20, 67 were men, the mean age was 55.5 years, and 50 patients had chronic diseases.
“All the data of included cases have been shared with [the World Health Organization]. The study was approved by Jinyintan Hospital Ethics Committee and written informed consent was obtained from patients involved before enrollment when data were collected retrospectively,” the researchers noted.
Nearly half of the patients (49%) lived or worked near a specific seafood market, suggesting disease clustering.
Clinical manifestations affecting the majority of patients included fever and cough in 83% and 82% of patients, respectively. Other symptoms included shortness of breath in 31%, muscle aches in 11%, confusion in 9%, headache in 8%, sore throat in 5%, and rhinorrhea, chest pain, diarrhea, and nausea and vomiting in 1%-4% of patients, the investigators found.
Imaging showed bilateral pneumonia in 75% of cases, multiple mottling and ground-glass opacity in 14%, and pneumothorax in 1%. Organ function damage was present in a third of patients at admission: 17% had acute respiratory distress syndrome (ARDS) – including 11 patients who worsened quickly and died of multiple organ failure. Eight percent had acute respiratory injury, 3% had acute renal injury, 4% had septic shock, and 1% had ventilator-associated pneumonia, they said, noting that all cases were confirmed by real-time polymerase chain reaction.
A notable laboratory finding was reduced absolute lymphocyte counts in most patients, the investigators said.
All patients were treated in isolation and 76% received antiviral treatment with oseltamivir, ganciclovir, lopinavir, or ritonavir for 3-14 days (median, 3 days). Most patients also received antibiotic treatment, including a single antibiotic in 25% of cases and combination therapy in 45%, with most antibiotics used to cover “common pathogens and some atypical pathogens,” they said, adding that “when secondary bacterial infection occurred, medication was administered according to the results of bacterial culture and drug sensitivity.”
Cephalosporins, quinolones, carbapenems, tigecycline against methicillin-resistant Staphylococcus aureus, linezolid, and antifungal drugs were used, and duration ranged from 3 to 17 days (median, 5 days).
Nineteen patients also received steroid treatments.
As of Jan. 25, 31 patients had been discharged and 57 remained hospitalized. Of the 11 who died, the first 2 were a 61-year-old man and a 69-year-old man, each diagnosed with severe pneumonia and ARDS. The first experienced sudden cardiac arrest and died on admission day 11, and the second died of severe pneumonia, septic shock, and respiratory failure on admission day 9. Neither had underlying disease, but both had a long history of smoking, the investigators noted.
“The deaths of these two patients were consistent with the MuLBSTA score,” they wrote, explaining that the scoring system takes into account multilobular infiltration, lymphopenia, bacterial coinfection, smoking history, hypertension, and age.
Eight of the nine other patients who died had lymphopenia, seven had bilateral pneumonia, five were over age 60 years, three had hypertension, and one was a heavy smoker, they added.
Most coronavirus infections cause mild symptoms and have good prognosis, but some patients with the 2019-nCoV, which was identified Jan. 7 following the development of several cases of pneumonia of unknown etiology in Wuhan, develop fatal disease. The paucity of data regarding epidemiology and clinical features of pneumonia associated with 2019-nCoV prompted the current retrospective study at the center where the first cases were admitted, the investigators explained.
They noted that the sequence of 2019-nCoV “is relatively different from the six other coronavirus subtypes, including the highly pathogenic severe acute respiratory syndrome (SARS)-CoV and Middle East Respiratory Syndrome (MERS)-CoV, as well as the human coronaviruses (HCoV)-OC43, -229E, -NL63, and -HKU1 that induce mild upper respiratory disease, but can be classified as a betacoronavirus with evidence of human-to-human transmission.
Mortality associated with SARS-CoV and MERS-CoV have been reported as more than 10% and more than 35%, respectively; at data cutoff for the current study, mortality among the 99 included cases was 11%, which is similar to that in another recent 2019-nCoV report, they said.
The finding of greater risk among older men also has been seen with SARS-CoV and MERS-CoV, and the high rate among individuals with chronic diseases, mainly cerebrovascular disease, cardiovascular disease, and diabetes, also has been reported with MERS-CoV, they added.
“Our results suggest that 2019-nCoV is more likely to infect older adult males with chronic comorbidities as a result of the weaker immune functions of these patients,” they wrote.
Coinfection with bacteria and fungi occurred in some patients, particularly those with severe illness, and cultures most often showed A. baumannii, K. pneumoniae, A. flavus, C. glabrata, and C. albicans, and the findings of reduced absolute lymphocyte values in most patients suggests that “2019-nCoV might mainly act on lymphocytes, especially T lymphocytes, as does SARS-CoV,” they noted.
Given the rapid progression with ARDS and septic shock in some patients in this review, “early identification and timely treatment of critical cases is of crucial importance,” they said.
“Use of intravenous immunoglobulin is recommended to enhance the ability of anti-infection for severely ill patients, and steroids (methylprednisolone 1-2 mg/kg per day) are recommended for patients with ARDS, for as short a duration of treatment as possible,” they added.
Further, since some studies suggest that a substantial decrease in lymphocyte count indicates consumption of many immune cells by coronavirus, thereby inhibiting cellular immune function, damage to T lymphocytes might be “an important factor leading to exacerbations of patients,” they wrote, adding that “[t]he low absolute value of lymphocytes could be used as a reference index in the diagnosis of new coronavirus infections in the clinic.”
The MuLBSTA score also should be investigated to determine its applicability for predicting mortality risk in patients with 2019-nCoV infection, they added.
The current study is limited by its small sample size; additional studies are needed to include “as many patients as possible in Wuhan, in other cities in China, and even in other countries to get a more comprehensive understanding of 2019-nCoV,” they said.
The National Key R&D Program of China funded the study. The authors reported having no conflicts of interest.
SOURCE: Chen N et al. Lancet. 2020 Jan 29. doi: 10.1016/S0140-6736(20)30211-7.
A group of physicians in Wuhan, China, who are treating patients with the 2019 novel coronavirus have gone the extra mile to share their clinical experiences with colleagues around the world.
Nanshan Chen, MD, of Jinyintan Hospital, Wuhan, and his team conducted a retrospective study on 99 cases and, in very short order, published their initial findings in the Lancet online on Jan. 29. These findings could guide action in other cases and help clinicians all over the world create treatment plans for patients of the 2019-nCoV.
The findings show that and characteristics of those with fatal infections align with the MuLBSTA score – an early warning model for predicting viral pneumonia–related mortality, according to a case review.
Of 99 patients who presented with 2019-nCoV pneumonia at Jinyintan Hospital between Jan. 1 and Jan. 20, 67 were men, the mean age was 55.5 years, and 50 patients had chronic diseases.
“All the data of included cases have been shared with [the World Health Organization]. The study was approved by Jinyintan Hospital Ethics Committee and written informed consent was obtained from patients involved before enrollment when data were collected retrospectively,” the researchers noted.
Nearly half of the patients (49%) lived or worked near a specific seafood market, suggesting disease clustering.
Clinical manifestations affecting the majority of patients included fever and cough in 83% and 82% of patients, respectively. Other symptoms included shortness of breath in 31%, muscle aches in 11%, confusion in 9%, headache in 8%, sore throat in 5%, and rhinorrhea, chest pain, diarrhea, and nausea and vomiting in 1%-4% of patients, the investigators found.
Imaging showed bilateral pneumonia in 75% of cases, multiple mottling and ground-glass opacity in 14%, and pneumothorax in 1%. Organ function damage was present in a third of patients at admission: 17% had acute respiratory distress syndrome (ARDS) – including 11 patients who worsened quickly and died of multiple organ failure. Eight percent had acute respiratory injury, 3% had acute renal injury, 4% had septic shock, and 1% had ventilator-associated pneumonia, they said, noting that all cases were confirmed by real-time polymerase chain reaction.
A notable laboratory finding was reduced absolute lymphocyte counts in most patients, the investigators said.
All patients were treated in isolation and 76% received antiviral treatment with oseltamivir, ganciclovir, lopinavir, or ritonavir for 3-14 days (median, 3 days). Most patients also received antibiotic treatment, including a single antibiotic in 25% of cases and combination therapy in 45%, with most antibiotics used to cover “common pathogens and some atypical pathogens,” they said, adding that “when secondary bacterial infection occurred, medication was administered according to the results of bacterial culture and drug sensitivity.”
Cephalosporins, quinolones, carbapenems, tigecycline against methicillin-resistant Staphylococcus aureus, linezolid, and antifungal drugs were used, and duration ranged from 3 to 17 days (median, 5 days).
Nineteen patients also received steroid treatments.
As of Jan. 25, 31 patients had been discharged and 57 remained hospitalized. Of the 11 who died, the first 2 were a 61-year-old man and a 69-year-old man, each diagnosed with severe pneumonia and ARDS. The first experienced sudden cardiac arrest and died on admission day 11, and the second died of severe pneumonia, septic shock, and respiratory failure on admission day 9. Neither had underlying disease, but both had a long history of smoking, the investigators noted.
“The deaths of these two patients were consistent with the MuLBSTA score,” they wrote, explaining that the scoring system takes into account multilobular infiltration, lymphopenia, bacterial coinfection, smoking history, hypertension, and age.
Eight of the nine other patients who died had lymphopenia, seven had bilateral pneumonia, five were over age 60 years, three had hypertension, and one was a heavy smoker, they added.
Most coronavirus infections cause mild symptoms and have good prognosis, but some patients with the 2019-nCoV, which was identified Jan. 7 following the development of several cases of pneumonia of unknown etiology in Wuhan, develop fatal disease. The paucity of data regarding epidemiology and clinical features of pneumonia associated with 2019-nCoV prompted the current retrospective study at the center where the first cases were admitted, the investigators explained.
They noted that the sequence of 2019-nCoV “is relatively different from the six other coronavirus subtypes, including the highly pathogenic severe acute respiratory syndrome (SARS)-CoV and Middle East Respiratory Syndrome (MERS)-CoV, as well as the human coronaviruses (HCoV)-OC43, -229E, -NL63, and -HKU1 that induce mild upper respiratory disease, but can be classified as a betacoronavirus with evidence of human-to-human transmission.
Mortality associated with SARS-CoV and MERS-CoV have been reported as more than 10% and more than 35%, respectively; at data cutoff for the current study, mortality among the 99 included cases was 11%, which is similar to that in another recent 2019-nCoV report, they said.
The finding of greater risk among older men also has been seen with SARS-CoV and MERS-CoV, and the high rate among individuals with chronic diseases, mainly cerebrovascular disease, cardiovascular disease, and diabetes, also has been reported with MERS-CoV, they added.
“Our results suggest that 2019-nCoV is more likely to infect older adult males with chronic comorbidities as a result of the weaker immune functions of these patients,” they wrote.
Coinfection with bacteria and fungi occurred in some patients, particularly those with severe illness, and cultures most often showed A. baumannii, K. pneumoniae, A. flavus, C. glabrata, and C. albicans, and the findings of reduced absolute lymphocyte values in most patients suggests that “2019-nCoV might mainly act on lymphocytes, especially T lymphocytes, as does SARS-CoV,” they noted.
Given the rapid progression with ARDS and septic shock in some patients in this review, “early identification and timely treatment of critical cases is of crucial importance,” they said.
“Use of intravenous immunoglobulin is recommended to enhance the ability of anti-infection for severely ill patients, and steroids (methylprednisolone 1-2 mg/kg per day) are recommended for patients with ARDS, for as short a duration of treatment as possible,” they added.
Further, since some studies suggest that a substantial decrease in lymphocyte count indicates consumption of many immune cells by coronavirus, thereby inhibiting cellular immune function, damage to T lymphocytes might be “an important factor leading to exacerbations of patients,” they wrote, adding that “[t]he low absolute value of lymphocytes could be used as a reference index in the diagnosis of new coronavirus infections in the clinic.”
The MuLBSTA score also should be investigated to determine its applicability for predicting mortality risk in patients with 2019-nCoV infection, they added.
The current study is limited by its small sample size; additional studies are needed to include “as many patients as possible in Wuhan, in other cities in China, and even in other countries to get a more comprehensive understanding of 2019-nCoV,” they said.
The National Key R&D Program of China funded the study. The authors reported having no conflicts of interest.
SOURCE: Chen N et al. Lancet. 2020 Jan 29. doi: 10.1016/S0140-6736(20)30211-7.
A group of physicians in Wuhan, China, who are treating patients with the 2019 novel coronavirus have gone the extra mile to share their clinical experiences with colleagues around the world.
Nanshan Chen, MD, of Jinyintan Hospital, Wuhan, and his team conducted a retrospective study on 99 cases and, in very short order, published their initial findings in the Lancet online on Jan. 29. These findings could guide action in other cases and help clinicians all over the world create treatment plans for patients of the 2019-nCoV.
The findings show that and characteristics of those with fatal infections align with the MuLBSTA score – an early warning model for predicting viral pneumonia–related mortality, according to a case review.
Of 99 patients who presented with 2019-nCoV pneumonia at Jinyintan Hospital between Jan. 1 and Jan. 20, 67 were men, the mean age was 55.5 years, and 50 patients had chronic diseases.
“All the data of included cases have been shared with [the World Health Organization]. The study was approved by Jinyintan Hospital Ethics Committee and written informed consent was obtained from patients involved before enrollment when data were collected retrospectively,” the researchers noted.
Nearly half of the patients (49%) lived or worked near a specific seafood market, suggesting disease clustering.
Clinical manifestations affecting the majority of patients included fever and cough in 83% and 82% of patients, respectively. Other symptoms included shortness of breath in 31%, muscle aches in 11%, confusion in 9%, headache in 8%, sore throat in 5%, and rhinorrhea, chest pain, diarrhea, and nausea and vomiting in 1%-4% of patients, the investigators found.
Imaging showed bilateral pneumonia in 75% of cases, multiple mottling and ground-glass opacity in 14%, and pneumothorax in 1%. Organ function damage was present in a third of patients at admission: 17% had acute respiratory distress syndrome (ARDS) – including 11 patients who worsened quickly and died of multiple organ failure. Eight percent had acute respiratory injury, 3% had acute renal injury, 4% had septic shock, and 1% had ventilator-associated pneumonia, they said, noting that all cases were confirmed by real-time polymerase chain reaction.
A notable laboratory finding was reduced absolute lymphocyte counts in most patients, the investigators said.
All patients were treated in isolation and 76% received antiviral treatment with oseltamivir, ganciclovir, lopinavir, or ritonavir for 3-14 days (median, 3 days). Most patients also received antibiotic treatment, including a single antibiotic in 25% of cases and combination therapy in 45%, with most antibiotics used to cover “common pathogens and some atypical pathogens,” they said, adding that “when secondary bacterial infection occurred, medication was administered according to the results of bacterial culture and drug sensitivity.”
Cephalosporins, quinolones, carbapenems, tigecycline against methicillin-resistant Staphylococcus aureus, linezolid, and antifungal drugs were used, and duration ranged from 3 to 17 days (median, 5 days).
Nineteen patients also received steroid treatments.
As of Jan. 25, 31 patients had been discharged and 57 remained hospitalized. Of the 11 who died, the first 2 were a 61-year-old man and a 69-year-old man, each diagnosed with severe pneumonia and ARDS. The first experienced sudden cardiac arrest and died on admission day 11, and the second died of severe pneumonia, septic shock, and respiratory failure on admission day 9. Neither had underlying disease, but both had a long history of smoking, the investigators noted.
“The deaths of these two patients were consistent with the MuLBSTA score,” they wrote, explaining that the scoring system takes into account multilobular infiltration, lymphopenia, bacterial coinfection, smoking history, hypertension, and age.
Eight of the nine other patients who died had lymphopenia, seven had bilateral pneumonia, five were over age 60 years, three had hypertension, and one was a heavy smoker, they added.
Most coronavirus infections cause mild symptoms and have good prognosis, but some patients with the 2019-nCoV, which was identified Jan. 7 following the development of several cases of pneumonia of unknown etiology in Wuhan, develop fatal disease. The paucity of data regarding epidemiology and clinical features of pneumonia associated with 2019-nCoV prompted the current retrospective study at the center where the first cases were admitted, the investigators explained.
They noted that the sequence of 2019-nCoV “is relatively different from the six other coronavirus subtypes, including the highly pathogenic severe acute respiratory syndrome (SARS)-CoV and Middle East Respiratory Syndrome (MERS)-CoV, as well as the human coronaviruses (HCoV)-OC43, -229E, -NL63, and -HKU1 that induce mild upper respiratory disease, but can be classified as a betacoronavirus with evidence of human-to-human transmission.
Mortality associated with SARS-CoV and MERS-CoV have been reported as more than 10% and more than 35%, respectively; at data cutoff for the current study, mortality among the 99 included cases was 11%, which is similar to that in another recent 2019-nCoV report, they said.
The finding of greater risk among older men also has been seen with SARS-CoV and MERS-CoV, and the high rate among individuals with chronic diseases, mainly cerebrovascular disease, cardiovascular disease, and diabetes, also has been reported with MERS-CoV, they added.
“Our results suggest that 2019-nCoV is more likely to infect older adult males with chronic comorbidities as a result of the weaker immune functions of these patients,” they wrote.
Coinfection with bacteria and fungi occurred in some patients, particularly those with severe illness, and cultures most often showed A. baumannii, K. pneumoniae, A. flavus, C. glabrata, and C. albicans, and the findings of reduced absolute lymphocyte values in most patients suggests that “2019-nCoV might mainly act on lymphocytes, especially T lymphocytes, as does SARS-CoV,” they noted.
Given the rapid progression with ARDS and septic shock in some patients in this review, “early identification and timely treatment of critical cases is of crucial importance,” they said.
“Use of intravenous immunoglobulin is recommended to enhance the ability of anti-infection for severely ill patients, and steroids (methylprednisolone 1-2 mg/kg per day) are recommended for patients with ARDS, for as short a duration of treatment as possible,” they added.
Further, since some studies suggest that a substantial decrease in lymphocyte count indicates consumption of many immune cells by coronavirus, thereby inhibiting cellular immune function, damage to T lymphocytes might be “an important factor leading to exacerbations of patients,” they wrote, adding that “[t]he low absolute value of lymphocytes could be used as a reference index in the diagnosis of new coronavirus infections in the clinic.”
The MuLBSTA score also should be investigated to determine its applicability for predicting mortality risk in patients with 2019-nCoV infection, they added.
The current study is limited by its small sample size; additional studies are needed to include “as many patients as possible in Wuhan, in other cities in China, and even in other countries to get a more comprehensive understanding of 2019-nCoV,” they said.
The National Key R&D Program of China funded the study. The authors reported having no conflicts of interest.
SOURCE: Chen N et al. Lancet. 2020 Jan 29. doi: 10.1016/S0140-6736(20)30211-7.
FROM THE LANCET
Nontuberculous Mycobacterial Pulmonary Disease
Nontuberculous mycobacterial pulmonary disease is a broad term for a group of pulmonary disorders caused and characterized by exposure to environmental mycobacteria other than those belonging to the Mycobacterium tuberculosis complex and Mycobacterium leprae. Mycobacteria are aerobic, nonmotile organisms that appear positive with acid-fast alcohol stains. Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and have been recovered from domestic and natural water sources, soil, and food products, and from around livestock, cattle, and wildlife.1-3 To date, no evidence exists of human-to-human or animal-to-human transmission of NTM in the general population. Infections in humans are usually acquired from environmental exposures, although the specific source of infection cannot always be identified. Similarly, the mode of infection with NTM has not been established with certainty, but it is highly likely that the organism is implanted, ingested, aspirated, or inhaled. Aerosolization of droplets associated with use of bathroom showerheads and municipal water sources and soil contamination are some of the factors associated with the transmission of infection. Proven routes of transmission include showerheads and potting soil dust.2,3
NTM pulmonary disease occurs in individuals with or without comorbid conditions such as bronchiectasis, chronic obstructive pulmonary disease, pulmonary fibrosis, or structural lung diseases. Slender, middle-aged or elderly white females with marfanoid body habitus, with or without apparent immune or genetic disorders, showing impaired airway and mucus clearance present with this infection as a form of underlying bronchiectasis (Lady Windermere syndrome). It is unclear why NTM infections and escalation to clinical disease occur in certain individuals. Many risk factors, including inherited and acquired defects of host immune response (eg, cystic fibrosis trait and α1 antitrypsin deficiency), have been associated with increased susceptibility to NTM infections.4
NTM infection can lead to chronic symptoms, frequent exacerbations, progressive functional and structural lung destruction, and impaired quality of life, and is associated with an increased risk of hospitalization and higher 5-year all-cause mortality. As such, NTM disease is drawing increasing attention at the clinical, academic, and research levels.5 This case-based review outlines the clinical features of NTM infection, with a focus on the challenges in diagnosis, treatment, and management of NTM pulmonary disease. The cases use Mycobacterium avium complex (MAC), a slow-growing mycobacteria (SGM), and Mycobacterium abscessus, a rapidly growing mycobacteria (RGM), as prototypes in a non–cystic fibrosis, non-HIV clinical setting.
Epidemiology
Of the almost 200 isolated species of NTM, the most prevalent pathogens for respiratory disease in the United States are MAC, Mycobacterium kansasii, and M. abscessus. MAC accounts for more than 80% of cases of NTM respiratory disease in the United States.6 The prevalence of NTM disease is increasing at a rate of about 8% each year, with 75,000 to 105,000 patients diagnosed with NTM lung disease in the United States annually. NTM infections in the United States are increasing among patients aged 65 years and older, a population that is expected to nearly double by 2030.7,8
Isolation and prevalence of many NTM species are higher in certain geographic areas of the United States, especially in the southeast. The US coastal regions have a higher prevalence of NTM pulmonary disease, and account for 70% of NTM cases in the United States each year. Half of patients diagnosed with NTM lung disease reside in 7 states: Florida, New York, Texas, California, Pennsylvania, New Jersey, and Ohio, with 1 in 7 residing in Florida. Three parishes in Louisiana are among the top 10 counties with the highest prevalence in United States. The prevalence of NTM infection–associated hospitalizations is increasing worldwide as well. Co-infection with tuberculosis and multiple NTMs in individual patients has been observed clinically and documented in patients with and without HIV.9,10
It is not clear why the prevalence of NTM pulmonary disease is increasing, but there may be several contributing factors: (1) an increased awareness and identification of NTM infection sources in the environment; (2) an expanding cohort of immunocompromised individuals with exogenous or endogenous immune deficiencies; (3) availability of improved diagnostic techniques, such as use of high-performance liquid chromatography (HPLC), DNA probes, and gene sequencing; and (4) an increased awareness of the morbidity and mortality associated with NTM pulmonary disease. However, it is important to recognize that to best understand the clinical relevance of epidemiologic studies based on laboratory diagnosis and identification, the findings must be evaluated by correlating them with the microbiological and other clinical criteria established by the American Thoracic Society (ATS)/Infectious Diseases Society of America (IDSA) guidelines.11
Continue to: Mycobacterium avium Complex
Mycobacterium avium Complex
Case Patient 1
A 48-year-old woman who has never smoked and has no past medical problems, except seasonal allergic rhinitis and “colds and flu-like illness” once or twice a year, is evaluated for a chronic lingering cough with occasional sputum production. The patient denies any other chronic symptoms and is otherwise active. Physical examination reveals no specific findings except mild pectus excavatum and mild scoliosis. Body mass index is 22 kg/m2. Chest radiograph shows nonspecific increased markings in the lower zones. Computed tomography (CT) scan of the chest reveals minimal nodular and cylindrical bronchiectasis in both lungs (Figure 1). No previous radiographs are available for comparison. The patient is HIV-negative. Sputum tests reveal normal flora, and both fungus and acid-fast bacilli smear are negative. Culture for mycobacteria shows scanty growth of MAC in 1 specimen.
What is the clinical presentation of MAC pulmonary disease?
Among NTM, MAC is the most common cause of pulmonary disease worldwide.6 MAC primarily includes 2 species: M. avium and Mycobacterium intracellulare. M. avium is the more important pathogen in disseminated disease, whereas M. intracellulare is the more common respiratory pathogen.11 These organisms are genetically similar and generally not differentiated in the clinical microbiology laboratory, although there are isolated reports in the literature suggesting differences in prevalence, presentation, and prognosis in M. avium infection versus M. intracellulare infection.12
Three major disease syndromes are produced by MAC in humans: pulmonary disease, usually in adults whose systemic immunity is intact; disseminated disease, usually in patients with advanced HIV infection; and cervical lymphadenitis.13 Pulmonary disease caused by MAC may take on 1 of several clinically different forms, including asymptomatic “colonization” or persistent minimal infection without obvious clinical significance; endobronchial involvement; progressive pulmonary disease with radiographic and clinical deterioration and nodular bronchiectasis or cavitary lung disease; hypersensitivity pneumonitis; or persistent, overwhelming mycobacterial growth with symptomatic manifestations, often in a lung with underlying damage due to either chronic obstructive lung disease or pulmonary fibrosis (Table 1).14
Cavitary Disease
The traditionally recognized presentation of MAC lung disease has been apical cavitary lung disease in men in their late 40s and early 50s who have a history of cigarette smoking, and frequently, excessive alcohol use. If left untreated, or in the case of erratic treatment or macrolide drug resistance, this form of disease is generally progressive within a relatively short time and can result in extensive cavitary lung destruction and progressive respiratory failure.15
Nodular Bronchiectasis
The more common presentation of MAC lung disease, which is outlined in the case described here, is interstitial nodular infiltrates, frequently involving the right middle lobe or lingula and predominantly occurring in postmenopausal, nonsmoking white women. This is sometimes labelled “Lady Windermere syndrome.” These patients with M. avium infection appear to have similar clinical characteristics and body types, including lean build, scoliosis, pectus excavatum, and mitral valve prolapse.16,17 The mechanism by which this body morphotype predisposes to pulmonary mycobacterial infection is not defined, but ineffective mucociliary clearance is a possible explanation. Evidence suggests that some patients may be predisposed to NTM lung disease because of preexisting bronchiectasis. Some potential etiologies of bronchiectasis in this population include chronic sinusitis, gastroesophageal reflux with chronic aspiration, α1 antitrypsin deficiency, and cystic fibrosis genetic traits and mutations.18 Risk factors for increased morbidity and mortality include the development of cavitary disease, age, weight loss, lower body mass index, and other comorbid conditions.
This form of disease, termed nodular bronchiectasis, tends to have a much slower progression than cavitary disease, such that long-term follow-up (months to years) may be necessary to demonstrate clinical or radiographic changes.11 The radiographic term “tree-in-bud” has been used to describe what may reflect inflammatory changes, including bronchiolitis. High-resolution CT scans of the chest are especially helpful for diagnosing this pattern of MAC lung disease, as bronchiectasis and small nodules may not be easily discernible on plain chest radiograph. The nodular/bronchiectasis radiographic pattern can also be seen with other NTM pathogens, including M. abscessus, Mycobacterium simiae, and M. kansasii. Solitary nodules and dense consolidation have also been described. Pleural effusions are uncommon, but reactive pleural thickening is frequently seen. Co-pathogens may be isolated from culture, including Pseudomonas aeruginosa, Staphylococcus aureus, and, occasionally, other NTM such as M. abscessus or Mycobacterium chelonae.19-21
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis, initially described in patients who were exposed to hot tubs, mimics allergic hypersensitivity pneumonitis, with respiratory symptoms and culture/tissue identification of MAC or sometimes other NTM. It is unclear whether hypersensitivity pneumonitis is an inflammatory process, an infection, or both, and opinion regarding the need for specific antibiotic treatment is divided.11,22 However, avoidance of exposure is prudent and recommended.
Disseminated Disease
Disseminated NTM disease is associated with very low CD4+ lymphocyte counts and is seen in approximately 5% of patients with HIV infection.23-25 Although disseminated NTM disease is rarely seen in immunosuppressed patients without HIV infection, it has been reported in patients who have undergone renal or cardiac transplant, patients on long-term corticosteroid therapy, and those with leukemia or lymphoma. More than 90% of infections are caused by MAC; other potential pathogens include M. kansasii, M. chelonae, M. abscessus, and Mycobacterium haemophilum. Although seen less frequently since the advent of highly active antiretroviral therapy, disseminated infection can develop progressively from an apparently indolent or localized infection or a respiratory or gastrointestinal source. Signs and symptoms of disseminated infection (specifically MAC-associated disease) are nonspecific and include fever, night sweats, weight loss, and abdominal tenderness. Disseminated MAC disease occurs primarily in patients with more advanced HIV disease (CD4+ count typically < 50 cells/μL). Clinically, disseminated MAC manifests as intermittent or persistent fever, constitutional symptoms with organomegaly and organ-specific abnormalities (eg, anemia, neutropenia from bone marrow involvement, adenopathy, hepatosplenomegaly), and elevations of liver enzymes or lung infiltrates from pulmonary involvement.
Continue to: What are the criteria for diagnosing NTM pulmonary disease?
What are the criteria for diagnosing NTM pulmonary disease?
The diagnosis of NTM disease is based on clinical, radiologic, and mycobacterial correlation with good communication between the experts in this field. The ATS/IDSA criteria for diagnosing NTM lung disease are shown in Figure 2. These criteria best apply to MAC, M. kansasii, and M. abscessus, but are also clinically applied to other NTM respiratory pathogens. The diagnosis of MAC infection is most readily established by culture of blood, bone marrow, respiratory secretions/fluid, or tissue specimens from suspected sites of involvement. Due to erratic shedding of MAC into the respiratory secretions in patients with nodular bronchiectasis, as compared to those with the cavitary form of the disease, sputum may be intermittently positive, with variable colony counts and polyclonal infections.12 Prior to the advent of high-resolution CT, isolation of MAC organisms from the sputum of such patients was frequently dismissed as colonization.
Mycobacterial Testing
Because of the nonspecific symptoms and lack of diagnostic specificity of chest imaging, the diagnosis of NTM lung disease requires microbiologic confirmation. Specimens sent to the laboratory for identification of NTM must be handled with care to prevent contamination and false-positive results. Transport media and preservatives should be avoided, and transportation of the specimens should be prompt. These measures will prevent bacterial overgrowth. Furthermore, the yield of NTM may be affected if the patient has used antibiotics, such as macrolides and fluoroquinolones, prior to obtaining the specimen.
NTM should be identified at the species and subspecies level, although this is not practical in community practice settings. The preferred staining procedure in the laboratory is the fluorochrome method. Some species require special growth conditions and/or lower incubation temperatures, and other identification methods may have to be employed, such as DNA probes, polymerase chain reaction genotyping, nucleic acid sequence determination, and high-performance liquid chromatography. As a gold standard, clinical specimens for mycobacterial cultures should be inoculated onto 1 or more solid media (eg, Middlebrook 7H11 media and/or Lowenstein-Jensen media, the former of which is the preferred medium for NTM) and into a liquid medium (eg, BACTEC 12B broth or Mycobacteria growth indicator tube broth). Growth of visible colonies on solid media typically requires 2 to 4 weeks, but liquid media (eg, the radiometric BACTEC system), used as a supplementary and not as an exclusive test, usually produce results within 10 to 14 days. Furthermore, even after initial growth, identification of specific isolates based on the growth characteristics on solid media requires additional time. Use of specific nucleic acid probes for MAC and M. kansasii and HPLC testing of mycolic acid patterns in acid-fast bacilli smear–positive specimens can reduce the turnaround time of specific identification of a primary culture–positive sample. However, HPLC is not sufficient for definitive identification of many NTM species, including the RGM. Other newer techniques, including 16S ribosomal DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism analysis, also allow NTM to be identified and speciated more reliably and rapidly from clinical specimens.
Cost and other practical considerations limit widespread adoption of these techniques. However, the recognition that M. abscessus can be separated into more than 1 subspecies, and that there are important prognostic implications of that separation, lends urgency to the broader adoption of newer molecular techniques in the mycobacteriology laboratory. Susceptibility testing is based on the broth microdilution method; RGM usually grow within 7 days of subculture, and the laboratory time to culture is a helpful hint, although not necessarily specific. Recognizing the morphology of mycobacterial colony growth may also be helpful in identification.
Are skin tests helpful in diagnosing NTM infection?
Tuberculin skin testing remains a nonspecific marker of mycobacterial infection and does not help in further elucidating NTM infection. However, epidemiologic and laboratory studies with well-characterized antigens have shown that dual skin testing with tuberculosis- versus NTM-derived tuberculin can discriminate between prior NTM and prior tuberculosis disease. Species-specific skin test antigens are not commercially available and are not helpful in the diagnosis of NTM disease because of cross-reactivity of M. tuberculosis and some NTM. However, increased prevalence of NTM sensitization based on purified protein derivative testing has been noted in a recent survey, which is consistent with an observed increase in the rates of NTM infections, specifically MAC, in the United States.26,27
Interferon-gamma release assays (IGRAs) are now being used as an alternative to tuberculin skin testing to diagnose M. tuberculosis infection. Certain NTM species also contain gene sequences that encode for ESAT-6 or CFP-10 antigens used in the IGRAs, and hence, yield a positive IGRA test. These include M. marinum, M. szulgai, and M. kansasii.28,29 However, MAC organisms do not produce positive results on assays that use these antigens.
Continue to: What is the approach to management of NTM pulmonary disease?
What is the approach to management of NTM pulmonary disease?
The correlation of symptoms with radiographic and microbiologic evidence is essential to categorize the disease and determine the need for therapy. Making the diagnosis of NTM lung disease does not necessitate the institution of therapy. The decision to treat should be weighed against potential risks and benefits to the individual patient based on symptomatic, radiographic, and microbiologic criteria, as well as underlying systemic or pulmonary immune status. In the absence of evidence of clinical, radiologic, or mycobacterial progression of disease, pursuing airway clearance therapy and clinical surveillance without initiating specific anti-MAC therapy is a reasonable option.11 Identifying the sustained presence of NTM infection, especially MAC, in a patient with underlying clinical and radiographic evidence of bronchiectasis is of value in determining comprehensive treatment and management strategies. Close observation is indicated if the decision not to treat is made. If treatment is initiated, comprehensive management includes long-term follow-up with periodic bacteriologic surveillance, watching for drug toxicity and drug-drug interactions, ensuring adherence and compliance to treatment, and managing comorbidity.
The Bronchiectasis Severity Index is a useful clinical predictive tool that identifies patients at risk of future mortality, hospitalization, and exacerbations and can be used to evaluate the need for specific treatment.30 The index is based on dyspnea score, lung function tests, colonization of pathogens, and extent of disease.
Case 1 Continued
After approximately 2 months of observation and symptomatic treatment, without specific antibiotic therapy, the patient’s symptoms continue. She now develops intermittent hemoptysis. Repeat sputum studies reveal moderate growth of M. avium. A follow-up CT scan shows progression of disease, with an increase in the tree-in-bud pattern (Figure 3).
What treatment protocols are recommended for MAC pulmonary disease?
As per the ATS/IDSA statement, macrolides are the mainstay of treatment for pulmonary MAC disease.11 Macrolides achieve an increased concentration in the lung, and when used for treatment of pulmonary MAC disease, there is a strong correlation between in vitro susceptibility, in vivo (clinical) response, and the immunomodulating effects of macrolides.31,32 Macrolide-containing regimens have demonstrated efficacy in patients with MAC pulmonary disease33,34; however, macrolide monotherapy should be avoided to prevent the development of resistance.
At the outset, it is critical to establish the objective criteria for determining response and to ensure that the patient understands the goals of the treatment and expectations of the treatment plan. Moreover, experts suggest that due to the possibility of drug intolerance, side effects, and the need for prolonged therapy, a “step ladder” ramping up approach to treatment could be adopted, with gradual introduction of therapy within a short time period; this approach may improve compliance and adherence to treatment.11 If this approach is used, the doses may have to be divided. Patients who are unable to tolerate daily medications, even with dosage adjustment, should be tried on an intermittent treatment regimen. Older female patients frequently require gradual introduction of medications (ie, 1 medication added to the regimen every 1 to 2 weeks) to evaluate tolerance to each medication and medication dose.11 Commonly encountered adverse effects of NTM treatment include intolerance to clarithromycin due to gastrointestinal problems, low body mass index, or age older than 70 years.
After determining that the patient requires therapy, the standard recommended treatment for MAC pulmonary disease includes the following: for most patients with nodular/bronchiectasis disease, a thrice-weekly regimen of clarithromycin (1000 mg) or azithromycin (500 mg), rifampin (600 mg), and ethambutol (25 mg/kg) is recommended. For patients with cavitary MAC pulmonary disease or severe nodular/bronchiectasis disease, the guidelines recommend a daily regimen of clarithromycin (500-1000 mg) or azithromycin (250 mg), rifampin (600 mg) or rifabutin (150–300 mg), and ethambutol (15 mg/kg), with consideration of intravenous (IV) amikacin 3 times/week early in therapy (Table 2).11
The treatment of MAC hypersensitivity-like disease speaks to the controversy of whether this is an inflammatory process, infectious process, or a combination of inflammation and infection. Avoidance of exposure is the mainstay of management. In some cases, steroids are used with or without a short course of anti-MAC therapy (ie, clarithromycin or azithromycin with rifampin and ethambutol).
Prophylaxis for disseminated MAC disease should be given to adults with HIV infection who have a CD4+ count less than 50 cells/μL. Azithromycin 1200 mg/week or clarithromycin 1000 mg/day has proven efficacy, and rifabutin 300 mg/day is also effective but less well tolerated. Rifabutin is more active in vitro against MAC than rifampin, and is used in HIV-positive patients because of drug-drug interaction between antiretroviral drugs and rifampin.
Continue to: Case 1 Continued
Case 1 Continued
The patient is treated with clarithromycin, rifampin, and ethambutol for 1 year, with sputum conversion after 9 months. In the latter part of her treatment, she experiences decreased visual acuity. Treatment is discontinued prematurely after 1 year due to drug toxicity and continued intolerance to drug therapy. The patient remains asymptomatic for 8 months, and then begins to experience mild to moderate hemoptysis, with increasing cough and sputum production associated with postural changes during exercise. Physical examination overall remains unchanged. Three sputum results reveal heavy growth of MAC, and a CT scan of the chest shows a cavitary lesion in the left upper lobe along with the nodular bronchiectasis (Figure 4).
What are the management options at this stage?
Based on this patient’s continued symptoms, progression of radiologic abnormalities, and current culture growth, she requires re-treatment. With the adverse effects associated with ethambutol during the first round of therapy, the drug regimen needs to be modified. Several considerations are relevant at this stage. Relapse rates range from 20% to 30% after treatment with a macrolide-based therapy.11,34 Obtaining a culture-sensitivity profile is imperative in these cases. Of note, treatment should not be discontinued altogether, but instead the toxic agent should be removed from the treatment regimen. Continuing treatment with a 2-drug regimen of clarithromycin and rifampin may be considered in this patient. Re-infection with multiple genotypes may also occur after successful drug therapy, but this is primarily seen in MAC patients with nodular bronchiectasis.34,35 Patients in whom previous therapy has failed, even those with macrolide-susceptible MAC isolates, are less likely to respond to subsequent therapy. Data suggest that intermittent medication dosing is not effective for patients with severe or cavitary disease or in those in whom previous therapy has failed.36 In this case, treatment should include a daily 3-drug therapy, with an injectable thrice-weekly aminoglycoside. Other agents such as linezolid and clofazimine may have to be tried. Cycloserine, ethionamide, and other agents are sometimes used, but their efficacy is unproven and doubtful. Pyrazinamide and isoniazid have no activity against MAC.
Treatment Failure and Drug Resistance
Treatment failure is considered to have occurred if patients have not had a response (microbiologic, clinical, or radiographic) after 6 months of appropriate therapy or had not achieved conversion of sputum to culture-negative after 12 months of appropriate therapy.11 This occurs in about 40% of patients. Multiple factors can interfere with the successful treatment of MAC pulmonary disease, including medication nonadherence, medication side effects or intolerance, lack of response to a medication regimen, or the emergence of a macrolide-resistant or multidrug-resistant strain. Inducible macrolide resistance remains a potential factor.34-36 A number of characteristics of NTM contribute to the poor response to currently used antibiotics: the organisms have a lipid outer membrane and prefer to adhere to surfaces and form biofilms, which makes them relatively impermeable to antibiotics.37 Also, NTM replicate in phagocytic cells, allowing them to subvert normal cellular defense mechanisms. Furthermore, NTM can display colony variants, whereby single colony isolates switch between antibiotic-susceptible and -resistant variants. These factors have also impeded in development of new antibiotics for NTM infection.37
Recent limited approval of amikacin liposomal inhalation suspension (ALIS) for treatment failure and refractory MAC infection in combination with guideline-based antimicrobial therapy (GBT) is a promising addition to the available treatment armamentarium. In a multinational trial, the addition of ALIS to GBT for treatment-refractory MAC lung disease achieved significantly greater culture conversion rates by month 6 than GBT alone, with comparable rates of serious adverse events.38
Is therapeutic drug monitoring recommended during treatment of MAC pulmonary disease?
Treatment failure may also be drug-related, including poor drug penetration into the damaged lung tissue or drug-drug interactions leading to suboptimal drug levels. Peak serum concentrations have been found to be below target ranges in approximately 50% of patients using a macrolide and ethambutol. Concurrent use of rifampin decreases the peak serum concentration of macrolides and quinolones, with acceptable target levels seen in only 18% to 57% of cases. Whether this alters patient outcomes is not clear.39-42 Factors identified as contributing to the poor response to therapy include poor compliance, cavitary disease, previous treatment for MAC pulmonary disease, and a history of chronic obstructive lung disease. Studies by Koh and colleagues40 and van Ingen and colleagues41 with pharmacokinetic and pharmacodynamics data showed that, in patients on MAC treatment with both clarithromycin and rifampicin, plasma levels of clarithromycin were lower than the recommended minimal inhibitory concentrations (MIC) against MAC for that drug. The studies also showed that rifampicin lowered clarithromycin concentrations more than did rifabutin, with the AUC/MIC ratio being suboptimal in nearly half the cases. However, low plasma clarithromycin concentrations did not have any correlation with treatment outcomes, as the peak plasma drug concentrations and the peak plasma drug concentration/MIC ratios did not differ between patients with unfavorable treatment outcomes and those with favorable outcomes. This is further compounded by the fact that macrolides achieve higher levels in lung tissue than in plasma, and hence the significance of low plasma levels is unclear; however, it is postulated that achieving higher drug levels could, in fact, lead to better clinical outcomes. Pending specific well-designed, prospective randomized controlled trials, routine therapeutic drug monitoring is not currently recommended, although some referral centers do this as their practice pattern.
Is surgery an option in this case?
The overall 5-year mortality for MAC pulmonary disease was approximately 28% in a retrospective analysis, with patients with cavitary disease at increased risk for death at 5 years.42 As such, surgery is an option in selected cases as part of adjunctive therapy along with anti-MAC therapy based on mycobacterial sensitivity. Surgery is used as either a curative approach or a “debulking” measure.11 When present, clearly localized disease, especially in the upper lobe, lends itself best to surgical intervention. Surgical resection of a solitary pulmonary nodule due to MAC, in addition to concomitant medical treatment, is recommended. Surgical intervention should be considered early in the course of the disease because it may provide a cure without prolonged treatment and its associated problems, and this approach may lead to early sputum conversion. Surgery should also be considered in patients with macrolide-resistant or multidrug-resistant MAC infection or in those who cannot tolerate the side effects of therapy, provided that the disease is focal and limited. Patients with poor preoperative lung function have poorer outcomes than those with good lung function, and postoperative complications arising from treatment, especially with a right-sided pneumonectomy, tend to occur more frequently in these patients. Thoracic surgery for NTM pulmonary disease must be considered cautiously, as this is associated with significant morbidity and mortality and is best performed at specialized centers that have expertise and experience in this field.43
Continue to: Mycobacterium abscessus Complex
Mycobacterium abscessus Complex
Case Patient 2
A 64-year-old man who is an ex-smoker presents with chronic cough, mild shortness of breath on exertion, low-grade fever, and unintentional weight loss of 10 lb. Physical exam is unremarkable. The patient was diagnosed with immunoglobulin deficiency (low IgM and low IgG4) in 2002, and has been on replacement therapy since then. He also has had multiple episodes of NTM infection, with MAC and M. kansasii infections diagnosed in 2012-2014, which required 18 months of multi-drug antibiotic treatment that resulted in sputum conversion. Pulmonary function testing done on this visit in 2017 shows mild obstructive impairment.
Chest radiograph and CT scan show bilateral bronchiectasis (Figure 5 and Figure 6).
The results of serial sputum microbiology testing performed over the course of 6 months are outlined below:
- 5/2017 (bronchoalveolar lavage): 2+; M. abscessus
- 9/2017 × 2: smear (–); group IV RGM
- 11/2017: smear (–); M. abscessus (> 50 CFU)
- 12/2017: smear (–); M. abscessus (> 50 CFU)
What are the clinical considerations in this patient with multiple NTM infections?
M. abscessus complex was originally described in soft tissue abscesses and skin infections possibly resulting from soil or water contamination. Subspeciation of M. abscessus complex during laboratory testing is critical to facilitate selection of a specific therapeutic approach; treatment decisions are impacted by the presence of an active erm gene and in vitro macrolide sensitivity, which differ between subspecies. The most acceptable classification outlines 3 species in the M. abscessus complex: Mycobacterium abscessus subsp abscessus, Mycobacterium abscessus subsp bolletii (both with an active erm gene responsible for macrolide resistance), and Mycobacterium abscessus subsp massiliense (with an inactive erm gene and therefore susceptible to macrolides).44
RGM typically manifest in skin, soft tissue, and bone, and can cause soft tissue, surgical wound, and catheter-related infections. Although the role of RGM as pulmonary pathogens is unclear, underlying diseases associated with RGM include previously treated mycobacterial disease, coexistent pulmonary diseases with or without MAC, cystic fibrosis, malignancies, and gastroesophageal disorders. M. abscessus is the third most commonly identified respiratory NTM and accounts for the majority (80%) of RGM respiratory isolates. Other NTM reported to cause both lung disease and skin, bone, and joint infections include Mycobacterium simiae, Mycobacterium xenopi, and Mycobacterium malmoense. Ocular granulomatous diseases, such as chorioretinitis and keratitis, have been reported with both RGM and Runyon group III SGM, such as MAC or M. szulgai, following trauma or refractive surgery. These can mimic fungal, herpetic, or amebic keratitis. The pulmonary syndromes associated with multiple culture positivity are seen in elderly women with bronchiectasis or cavitary lung disease and/or associated with gastrointestinal symptoms of acid reflux, with or without achalasia and concomitant lipoid interstitial pneumonia.45
Generally, pulmonary disease progresses slowly, but lung disease attributed to RGM can result in respiratory failure. Thus, RGM should be recognized as a possible cause of chronic mycobacterial lung disease, especially in immunocompromised patients, and respiratory isolates should be assessed carefully. Identification and drug susceptibility testing are essential before initiation of treatment for RGM.
What is the approach to management of M. abscessus pulmonary disease in a patient without cystic fibrosis?
The management of M. abscessus pulmonary infection as a subset of RGM requires a considered step-wise approach. The criteria for diagnosis and threshold for starting treatment are the same as those used in the management of MAC pulmonary disease,11 but the treatment of M. abscessus pulmonary infection is more complex and has lower rates of success and cure. Also, antibiotic treatment presents challenges related to rapid identification of the causative organism, nomenclature, resistance patterns, and tolerance of treatment and side effects. If a source such as catheter, access port, or any surgical site is identified, prompt removal and clearance of the infected site are strongly advised
In the absence of any controlled clinical trials, treatment of RGM is based on in vitro susceptibility testing and expert opinion. As in MAC pulmonary disease, macrolides are the mainstay of treatment, with an induction phase of intravenous antibiotics. Treatment may include a combination of injectable aminoglycosides, imipenem, or cefoxitin and oral drugs such as a macrolide (eg, clarithromycin, azithromycin), doxycycline, fluoroquinolones, trimethoprim/sulfamethoxazole, or linezolid. While antibiotic treatment of M. abscessus pulmonary disease is based on in vitro sensitivity pattern to a greater degree than is treatment of MAC pulmonary disease, this approach has significant practical limitations and hence variable applicability. The final choice of antibiotics is best based on the extended susceptibility results, if available. The presence of an active erm gene on a prolonged growth specimen in M. abscessus subsp abscessus and M. abscessus subsp bolletii precludes the use of a macrolide. In such cases, amikacin, especially in an intravenous form, is the mainstay of treatment based on MIC. Recently, there has been a resurgence in interest in the use of clofazimine in combination with amikacin when treatment is not successful in patients with M. abscessus subsp abscessus or M. bolletii with an active erm gene.45,46 When localized abscess formation is noted, surgery may be the best option, with emphasis on removal of implants and catheters if implicated in RGM infection.
Attention must also be given to confounding pulmonary and associated comorbidities. This includes management of bronchiectasis with appropriately aggressive airway clearance techniques; anti-reflux measures for prevention of micro-aspiration; and management of other comorbid pulmonary conditions, such as chronic obstructive pulmonary disease, pulmonary fibrosis, and sarcoidosis, if applicable. These interventions play a critical role in clearing the M. abscessus infection, preventing progression of disease, and reducing morbidity. The role of immunomodulatory therapy needs to be considered on a regular, ongoing basis. Identification of genetic factors and correction of immune deficiencies may help in managing the infection.
Case Patient 2 Conclusion
The treatment regimen adopted in this case includes a 3-month course of daily intravenous amikacin and imipenem with oral azithromycin, followed by a continuation phase of azithromycin with clofazimine and linezolid. Airway clearance techniques such as Vest/Acapella/CPT are intensified and monthly intravenous immunoglobulin therapy is continued. The patient responds to treatment, with resolution of his clinical symptoms and reduction in the colony count of M. abscessus in the sputum.
Summary
NTM are ubiquitous in the environment, and NTM infection has variable manifestations, especially in patients with no recognizable immune impairments. Underlying comorbid conditions with bronchiectasis complicate its management. Treatment strategies must be individualized based on degree of involvement, associated comorbidities, immune deficiencies, goals of therapy, outcome-based risk-benefit ratio assessment, and patient engagement and expectations. In diffuse pulmonary disease, drug treatment remains difficult due to poor match of in vitro and in vivo culture sensitivity, side effects of medications, and high failure rates. When a localized resectable foci of infection is identified, especially in RGM disease, surgical treatment may be the best approach in selected patients, but it must be performed in centers with expertise and experience in this field.
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2. Falkinham JO III. Environmental sources of NTM. Clin Chest Med. 2015;36:35-41.
3. Falkinham JO III, Current epidemiological trends in NTM. Curr Environ Health Rep. 2016;3:161-167.
4. Honda JR, Knight V, Chan ED. Pathogenesis and risk factors for nontuberculous mycobacterial lung disease. Clin Chest Med. 2015;36:1-11.
5. Marras TK, Mirsaeidi M, Chou E, et al. Health care utilization and expenditures following diagnosis of nontuberculous mycobacterial lung disease in the United States. Manag Care Spec Pharm. 2018;24:964-974.
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10. Aliyu G, El-Kamary SS, Abimiku A, et al. Prevalence of non-tuberculous mycobacterial infections among tuberculosis suspects in Nigeria. PLoS One. 2013;8:e63170.
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12. Wallace RJ Jr, Zhang Y, Brown BA, et al. Polyclonal Mycobacterium avium complex infections in patients with nodular bronchiectasis. Am J Respir Crit Care Med. 1998;158:1235-1244.
13. Gordin FM, Horsburgh CR Jr. Mycobacterium avium complex. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia: Elsevier; 2015.
14. Chitty S, Ali J. Mycobacterium avium complex pulmonary disease in immune competent patients. South Med J. 2005;98:646-52.
15. Ramirez J, Mason C, Ali J, Lopez FA. MAC pulmonary disease: management options in HIV-negative patients. J La State Med Soc. 2008;160:248-254.
16. Iseman MD, Buschman DL, Ackerson LM. Pectus excavatum and scoliosis. Thoracic anomalies associated with pulmonary disease caused by Mycobacterium avium complex. Am Rev Respir Dis. 1991;144:914-916.
17. Kim RD, Greenburg DE, Ehrmantraut ME, et al. Pulmonary nontuberculous mycobacterial disease: prospective study of a distinct preexisting syndrome. Am J Respir Crit Care Med. 2008;178:1066-1074.
18. Ziedalski TM, Kao PN, Henig NR, et al. Prospective analysis of cystic fibrosis transmembrane regulator mutations in adults with bronchiectasis or pulmonary nontuberculous mycobacterial infection. Chest. 2006;130:995-1002.
19. Koh WJ, Lee KS, Kwon OJ, et al. Bilateral bronchiectasis and bronchiolitis at thin-section CT: diagnostic implications in nontuberculous mycobacterial pulmonary infection. Radiology. 2005;235:282-288.
20. Swensen SJ, Hartman TE, Williams DE. Computed tomographic diagnosis of Mycobacterium avium-intracellulare complex in patients with bronchiectasis. Chest. 1994;105:49-52.
21. Huang JH, Kao PN, Adi V, Ruoss SJ. Mycobacterium avium intracellulare pulmonary infection in HIV-negative patients without preexisting lung disease: diagnostic and management limitations. Chest. 1999;115:1033-1040.
22. Cappelluti E, Fraire AE, Schaefer OP. A case of “hot tub lung” due to Mycobacterium avium complex in an immunocompetent host. Arch Intern Med. 2003;163:845-848.
23. Nightingale SD, Byrd LT, Southern PM, et al. Incidence of Mycobacterium avium-intracellulare complex bacteremia in human immunodeficiency virus-positive patients. J Infect Dis. 1992;165:1082-1085.
24. Horsburgh CR Jr, Selik RM. The epidemiology of disseminated tuberculous mycobacterial infection in the acquired immunodeficiency syndrome (AIDS). Am Rev Respir Dis. 1989;139:4-7.
25. Chin DP, Hopewell PC, Yajko DM, et al. Mycobacterium avium complex in the respiratory or gastrointestinal tract and the risk of M. avium complex bacteremia in patients with human immunodeficiency virus infection. J Infect Dis. 1994;169:289-295.
26. Khan K, Wang J, Marras TK. Nontuberculous mycobacterial sensitization in the United States: national trends over three decades. Am J Respir Crit Care Med. 2007;176:306-313.
27. Lillo M, Orengo S, Cernoch P, Harris RL. Pulmonary and disseminated infection due to Mycobacterium kansasii: a decade of experience. Rev Infect Dis. 1990;12:760-767.
28. Andersen P, Munk ME, Pollock JM, Doherty TM. Specific immune-based diagnosis of tuberculosis. Lancet. 2000;356:1099-1104.
29. Arend SM, van Meijgaarden KE, de Boer K, et al. Tuberculin skin testing and in vitro T cell responses to ESAT-6 and culture filtrate protein 10 after infection with Mycobacterium marinum or M. kansasii. J Infect Dis. 2002;186:1797-1807.
30. James D, Chalmers JD, Goeminne P, et al. The Bronchiectasis Severity Index: an international derivation and validation study. Am J Respir Crit Care Med. 2014;189:576-585.
31. Heifets L. MIC as a quantitative measurement of the susceptibility of Mycobacterium avium strains to seven antituberculosis drugs. Antimicrob Agents Chemother. 1988;32:1131-1136.
32. Horsburgh CR Jr, Mason UG 3rd, Heifits LB, et al. Response to therapy of pulmonary Mycobacterium avium intracellulare infection correlates with results of in vitro susceptibility testing. Am Rev Respir Dis. 1987;135:418-421.
33. Rubin BK, Henke MO. Immunomodulatory activity and effectiveness of macrolides in chronic airway disease. Chest. 2004;125(2 Suppl):70S-78S.
34. Wallace RJ Jr, Brown BA, Griffith DE, et al. Clarithromycin regimens for pulmonary Mycobacterium avium complex. The first 50 patients. Am J Respir Crit Care Med. 1996;153:1766-1772.
35. Griffith DE, Brown-Elliott BA, Langsjoen B, et al. Clinical and molecular analysis of macrolide resistance in Mycobacterium avium complex lung disease. Am J Respir Crit Care Med. 2006;174:928-934.
36. Lam PK, Griffith DE, Aksamit TR, et al. Factors related to response to intermittent treatment of Mycobacterium avium complex lung disease. Am J Respir Crit Care Med. 2006;173:1283-1289.
37. Falkinham J III. Challenges of NTM drug development. Front Microbiol. 2018;9:1613.
38. Griffith DE, Eagle G, Thomson R, et al. Amikacin liposome inhalation suspension for treatment-refractory lung disease caused by Mycobacterium avium complex (CONVERT). A prospective, open-label, randomized study. Am J Respir Crit Care Med. 2018;198:1559-1569.
39. Schluger NW. Treatment of pulmonary Mycobacterium avium complex infections: do drug levels matter? Am J Respir Crit Care Med. 2012;186:710-711.
40. Van Ingen J, Egelund EF, Levin A, et al. The pharmacokinetics and pharmacodynamics of pulmonary Mycobacterium avium complex disease treatment. Am J Respir Crit Care Med. 2012;186:559-565.
41. Koh WJ, Jeong BH, Jeon K, et al. Therapeutic drug monitoring in the treatment of Mycobacterium avium complex lung disease. Am J Respir Crit Care Med. 2012;186:797-802.
42. Ito Y, Hirai T, Maekawa K, et al. Predictors of 5-year mortality in pulmonary MAC disease. Int J Tuberc Lung Dis. 2012;16:408-414.
43. Yuji S, Yutsuki N, Keiichiso T, et al. Surgery for Mycobacterium avium lung disease in the clarithromycin era. Eur J Cardiothor Surg. 2002;21:314-318.
44. Tortoli E, Kohl TA, Brown-Elliott BA, et al. Emended description of Mycobacterium abscessus, Mycobacterium abscessus subsp. abscessus and Mycobacterium abscessus subsp. bolletii and designation of Mycobacterium abscessus subsp. massiliense comb. Int J Syst Evol Microbiol. 2016; 66:4471-4479.
45. Griffith DE, Girard WM, Wallace RJ Jr. Clinical features of pulmonary disease caused by rapidly growing mycobacteria. An analysis of 154 patients. Am Rev Respir Dis. 1993;147:1271-1278.
46. Koh WJ, Jeong BH, Kim SY, et al. Mycobacterial characteristics and treatment outcomes in Mycobacterium abscessus lung disease. Clin Infect Dis. 2017;64:309-316.
Nontuberculous mycobacterial pulmonary disease is a broad term for a group of pulmonary disorders caused and characterized by exposure to environmental mycobacteria other than those belonging to the Mycobacterium tuberculosis complex and Mycobacterium leprae. Mycobacteria are aerobic, nonmotile organisms that appear positive with acid-fast alcohol stains. Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and have been recovered from domestic and natural water sources, soil, and food products, and from around livestock, cattle, and wildlife.1-3 To date, no evidence exists of human-to-human or animal-to-human transmission of NTM in the general population. Infections in humans are usually acquired from environmental exposures, although the specific source of infection cannot always be identified. Similarly, the mode of infection with NTM has not been established with certainty, but it is highly likely that the organism is implanted, ingested, aspirated, or inhaled. Aerosolization of droplets associated with use of bathroom showerheads and municipal water sources and soil contamination are some of the factors associated with the transmission of infection. Proven routes of transmission include showerheads and potting soil dust.2,3
NTM pulmonary disease occurs in individuals with or without comorbid conditions such as bronchiectasis, chronic obstructive pulmonary disease, pulmonary fibrosis, or structural lung diseases. Slender, middle-aged or elderly white females with marfanoid body habitus, with or without apparent immune or genetic disorders, showing impaired airway and mucus clearance present with this infection as a form of underlying bronchiectasis (Lady Windermere syndrome). It is unclear why NTM infections and escalation to clinical disease occur in certain individuals. Many risk factors, including inherited and acquired defects of host immune response (eg, cystic fibrosis trait and α1 antitrypsin deficiency), have been associated with increased susceptibility to NTM infections.4
NTM infection can lead to chronic symptoms, frequent exacerbations, progressive functional and structural lung destruction, and impaired quality of life, and is associated with an increased risk of hospitalization and higher 5-year all-cause mortality. As such, NTM disease is drawing increasing attention at the clinical, academic, and research levels.5 This case-based review outlines the clinical features of NTM infection, with a focus on the challenges in diagnosis, treatment, and management of NTM pulmonary disease. The cases use Mycobacterium avium complex (MAC), a slow-growing mycobacteria (SGM), and Mycobacterium abscessus, a rapidly growing mycobacteria (RGM), as prototypes in a non–cystic fibrosis, non-HIV clinical setting.
Epidemiology
Of the almost 200 isolated species of NTM, the most prevalent pathogens for respiratory disease in the United States are MAC, Mycobacterium kansasii, and M. abscessus. MAC accounts for more than 80% of cases of NTM respiratory disease in the United States.6 The prevalence of NTM disease is increasing at a rate of about 8% each year, with 75,000 to 105,000 patients diagnosed with NTM lung disease in the United States annually. NTM infections in the United States are increasing among patients aged 65 years and older, a population that is expected to nearly double by 2030.7,8
Isolation and prevalence of many NTM species are higher in certain geographic areas of the United States, especially in the southeast. The US coastal regions have a higher prevalence of NTM pulmonary disease, and account for 70% of NTM cases in the United States each year. Half of patients diagnosed with NTM lung disease reside in 7 states: Florida, New York, Texas, California, Pennsylvania, New Jersey, and Ohio, with 1 in 7 residing in Florida. Three parishes in Louisiana are among the top 10 counties with the highest prevalence in United States. The prevalence of NTM infection–associated hospitalizations is increasing worldwide as well. Co-infection with tuberculosis and multiple NTMs in individual patients has been observed clinically and documented in patients with and without HIV.9,10
It is not clear why the prevalence of NTM pulmonary disease is increasing, but there may be several contributing factors: (1) an increased awareness and identification of NTM infection sources in the environment; (2) an expanding cohort of immunocompromised individuals with exogenous or endogenous immune deficiencies; (3) availability of improved diagnostic techniques, such as use of high-performance liquid chromatography (HPLC), DNA probes, and gene sequencing; and (4) an increased awareness of the morbidity and mortality associated with NTM pulmonary disease. However, it is important to recognize that to best understand the clinical relevance of epidemiologic studies based on laboratory diagnosis and identification, the findings must be evaluated by correlating them with the microbiological and other clinical criteria established by the American Thoracic Society (ATS)/Infectious Diseases Society of America (IDSA) guidelines.11
Continue to: Mycobacterium avium Complex
Mycobacterium avium Complex
Case Patient 1
A 48-year-old woman who has never smoked and has no past medical problems, except seasonal allergic rhinitis and “colds and flu-like illness” once or twice a year, is evaluated for a chronic lingering cough with occasional sputum production. The patient denies any other chronic symptoms and is otherwise active. Physical examination reveals no specific findings except mild pectus excavatum and mild scoliosis. Body mass index is 22 kg/m2. Chest radiograph shows nonspecific increased markings in the lower zones. Computed tomography (CT) scan of the chest reveals minimal nodular and cylindrical bronchiectasis in both lungs (Figure 1). No previous radiographs are available for comparison. The patient is HIV-negative. Sputum tests reveal normal flora, and both fungus and acid-fast bacilli smear are negative. Culture for mycobacteria shows scanty growth of MAC in 1 specimen.
What is the clinical presentation of MAC pulmonary disease?
Among NTM, MAC is the most common cause of pulmonary disease worldwide.6 MAC primarily includes 2 species: M. avium and Mycobacterium intracellulare. M. avium is the more important pathogen in disseminated disease, whereas M. intracellulare is the more common respiratory pathogen.11 These organisms are genetically similar and generally not differentiated in the clinical microbiology laboratory, although there are isolated reports in the literature suggesting differences in prevalence, presentation, and prognosis in M. avium infection versus M. intracellulare infection.12
Three major disease syndromes are produced by MAC in humans: pulmonary disease, usually in adults whose systemic immunity is intact; disseminated disease, usually in patients with advanced HIV infection; and cervical lymphadenitis.13 Pulmonary disease caused by MAC may take on 1 of several clinically different forms, including asymptomatic “colonization” or persistent minimal infection without obvious clinical significance; endobronchial involvement; progressive pulmonary disease with radiographic and clinical deterioration and nodular bronchiectasis or cavitary lung disease; hypersensitivity pneumonitis; or persistent, overwhelming mycobacterial growth with symptomatic manifestations, often in a lung with underlying damage due to either chronic obstructive lung disease or pulmonary fibrosis (Table 1).14
Cavitary Disease
The traditionally recognized presentation of MAC lung disease has been apical cavitary lung disease in men in their late 40s and early 50s who have a history of cigarette smoking, and frequently, excessive alcohol use. If left untreated, or in the case of erratic treatment or macrolide drug resistance, this form of disease is generally progressive within a relatively short time and can result in extensive cavitary lung destruction and progressive respiratory failure.15
Nodular Bronchiectasis
The more common presentation of MAC lung disease, which is outlined in the case described here, is interstitial nodular infiltrates, frequently involving the right middle lobe or lingula and predominantly occurring in postmenopausal, nonsmoking white women. This is sometimes labelled “Lady Windermere syndrome.” These patients with M. avium infection appear to have similar clinical characteristics and body types, including lean build, scoliosis, pectus excavatum, and mitral valve prolapse.16,17 The mechanism by which this body morphotype predisposes to pulmonary mycobacterial infection is not defined, but ineffective mucociliary clearance is a possible explanation. Evidence suggests that some patients may be predisposed to NTM lung disease because of preexisting bronchiectasis. Some potential etiologies of bronchiectasis in this population include chronic sinusitis, gastroesophageal reflux with chronic aspiration, α1 antitrypsin deficiency, and cystic fibrosis genetic traits and mutations.18 Risk factors for increased morbidity and mortality include the development of cavitary disease, age, weight loss, lower body mass index, and other comorbid conditions.
This form of disease, termed nodular bronchiectasis, tends to have a much slower progression than cavitary disease, such that long-term follow-up (months to years) may be necessary to demonstrate clinical or radiographic changes.11 The radiographic term “tree-in-bud” has been used to describe what may reflect inflammatory changes, including bronchiolitis. High-resolution CT scans of the chest are especially helpful for diagnosing this pattern of MAC lung disease, as bronchiectasis and small nodules may not be easily discernible on plain chest radiograph. The nodular/bronchiectasis radiographic pattern can also be seen with other NTM pathogens, including M. abscessus, Mycobacterium simiae, and M. kansasii. Solitary nodules and dense consolidation have also been described. Pleural effusions are uncommon, but reactive pleural thickening is frequently seen. Co-pathogens may be isolated from culture, including Pseudomonas aeruginosa, Staphylococcus aureus, and, occasionally, other NTM such as M. abscessus or Mycobacterium chelonae.19-21
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis, initially described in patients who were exposed to hot tubs, mimics allergic hypersensitivity pneumonitis, with respiratory symptoms and culture/tissue identification of MAC or sometimes other NTM. It is unclear whether hypersensitivity pneumonitis is an inflammatory process, an infection, or both, and opinion regarding the need for specific antibiotic treatment is divided.11,22 However, avoidance of exposure is prudent and recommended.
Disseminated Disease
Disseminated NTM disease is associated with very low CD4+ lymphocyte counts and is seen in approximately 5% of patients with HIV infection.23-25 Although disseminated NTM disease is rarely seen in immunosuppressed patients without HIV infection, it has been reported in patients who have undergone renal or cardiac transplant, patients on long-term corticosteroid therapy, and those with leukemia or lymphoma. More than 90% of infections are caused by MAC; other potential pathogens include M. kansasii, M. chelonae, M. abscessus, and Mycobacterium haemophilum. Although seen less frequently since the advent of highly active antiretroviral therapy, disseminated infection can develop progressively from an apparently indolent or localized infection or a respiratory or gastrointestinal source. Signs and symptoms of disseminated infection (specifically MAC-associated disease) are nonspecific and include fever, night sweats, weight loss, and abdominal tenderness. Disseminated MAC disease occurs primarily in patients with more advanced HIV disease (CD4+ count typically < 50 cells/μL). Clinically, disseminated MAC manifests as intermittent or persistent fever, constitutional symptoms with organomegaly and organ-specific abnormalities (eg, anemia, neutropenia from bone marrow involvement, adenopathy, hepatosplenomegaly), and elevations of liver enzymes or lung infiltrates from pulmonary involvement.
Continue to: What are the criteria for diagnosing NTM pulmonary disease?
What are the criteria for diagnosing NTM pulmonary disease?
The diagnosis of NTM disease is based on clinical, radiologic, and mycobacterial correlation with good communication between the experts in this field. The ATS/IDSA criteria for diagnosing NTM lung disease are shown in Figure 2. These criteria best apply to MAC, M. kansasii, and M. abscessus, but are also clinically applied to other NTM respiratory pathogens. The diagnosis of MAC infection is most readily established by culture of blood, bone marrow, respiratory secretions/fluid, or tissue specimens from suspected sites of involvement. Due to erratic shedding of MAC into the respiratory secretions in patients with nodular bronchiectasis, as compared to those with the cavitary form of the disease, sputum may be intermittently positive, with variable colony counts and polyclonal infections.12 Prior to the advent of high-resolution CT, isolation of MAC organisms from the sputum of such patients was frequently dismissed as colonization.
Mycobacterial Testing
Because of the nonspecific symptoms and lack of diagnostic specificity of chest imaging, the diagnosis of NTM lung disease requires microbiologic confirmation. Specimens sent to the laboratory for identification of NTM must be handled with care to prevent contamination and false-positive results. Transport media and preservatives should be avoided, and transportation of the specimens should be prompt. These measures will prevent bacterial overgrowth. Furthermore, the yield of NTM may be affected if the patient has used antibiotics, such as macrolides and fluoroquinolones, prior to obtaining the specimen.
NTM should be identified at the species and subspecies level, although this is not practical in community practice settings. The preferred staining procedure in the laboratory is the fluorochrome method. Some species require special growth conditions and/or lower incubation temperatures, and other identification methods may have to be employed, such as DNA probes, polymerase chain reaction genotyping, nucleic acid sequence determination, and high-performance liquid chromatography. As a gold standard, clinical specimens for mycobacterial cultures should be inoculated onto 1 or more solid media (eg, Middlebrook 7H11 media and/or Lowenstein-Jensen media, the former of which is the preferred medium for NTM) and into a liquid medium (eg, BACTEC 12B broth or Mycobacteria growth indicator tube broth). Growth of visible colonies on solid media typically requires 2 to 4 weeks, but liquid media (eg, the radiometric BACTEC system), used as a supplementary and not as an exclusive test, usually produce results within 10 to 14 days. Furthermore, even after initial growth, identification of specific isolates based on the growth characteristics on solid media requires additional time. Use of specific nucleic acid probes for MAC and M. kansasii and HPLC testing of mycolic acid patterns in acid-fast bacilli smear–positive specimens can reduce the turnaround time of specific identification of a primary culture–positive sample. However, HPLC is not sufficient for definitive identification of many NTM species, including the RGM. Other newer techniques, including 16S ribosomal DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism analysis, also allow NTM to be identified and speciated more reliably and rapidly from clinical specimens.
Cost and other practical considerations limit widespread adoption of these techniques. However, the recognition that M. abscessus can be separated into more than 1 subspecies, and that there are important prognostic implications of that separation, lends urgency to the broader adoption of newer molecular techniques in the mycobacteriology laboratory. Susceptibility testing is based on the broth microdilution method; RGM usually grow within 7 days of subculture, and the laboratory time to culture is a helpful hint, although not necessarily specific. Recognizing the morphology of mycobacterial colony growth may also be helpful in identification.
Are skin tests helpful in diagnosing NTM infection?
Tuberculin skin testing remains a nonspecific marker of mycobacterial infection and does not help in further elucidating NTM infection. However, epidemiologic and laboratory studies with well-characterized antigens have shown that dual skin testing with tuberculosis- versus NTM-derived tuberculin can discriminate between prior NTM and prior tuberculosis disease. Species-specific skin test antigens are not commercially available and are not helpful in the diagnosis of NTM disease because of cross-reactivity of M. tuberculosis and some NTM. However, increased prevalence of NTM sensitization based on purified protein derivative testing has been noted in a recent survey, which is consistent with an observed increase in the rates of NTM infections, specifically MAC, in the United States.26,27
Interferon-gamma release assays (IGRAs) are now being used as an alternative to tuberculin skin testing to diagnose M. tuberculosis infection. Certain NTM species also contain gene sequences that encode for ESAT-6 or CFP-10 antigens used in the IGRAs, and hence, yield a positive IGRA test. These include M. marinum, M. szulgai, and M. kansasii.28,29 However, MAC organisms do not produce positive results on assays that use these antigens.
Continue to: What is the approach to management of NTM pulmonary disease?
What is the approach to management of NTM pulmonary disease?
The correlation of symptoms with radiographic and microbiologic evidence is essential to categorize the disease and determine the need for therapy. Making the diagnosis of NTM lung disease does not necessitate the institution of therapy. The decision to treat should be weighed against potential risks and benefits to the individual patient based on symptomatic, radiographic, and microbiologic criteria, as well as underlying systemic or pulmonary immune status. In the absence of evidence of clinical, radiologic, or mycobacterial progression of disease, pursuing airway clearance therapy and clinical surveillance without initiating specific anti-MAC therapy is a reasonable option.11 Identifying the sustained presence of NTM infection, especially MAC, in a patient with underlying clinical and radiographic evidence of bronchiectasis is of value in determining comprehensive treatment and management strategies. Close observation is indicated if the decision not to treat is made. If treatment is initiated, comprehensive management includes long-term follow-up with periodic bacteriologic surveillance, watching for drug toxicity and drug-drug interactions, ensuring adherence and compliance to treatment, and managing comorbidity.
The Bronchiectasis Severity Index is a useful clinical predictive tool that identifies patients at risk of future mortality, hospitalization, and exacerbations and can be used to evaluate the need for specific treatment.30 The index is based on dyspnea score, lung function tests, colonization of pathogens, and extent of disease.
Case 1 Continued
After approximately 2 months of observation and symptomatic treatment, without specific antibiotic therapy, the patient’s symptoms continue. She now develops intermittent hemoptysis. Repeat sputum studies reveal moderate growth of M. avium. A follow-up CT scan shows progression of disease, with an increase in the tree-in-bud pattern (Figure 3).
What treatment protocols are recommended for MAC pulmonary disease?
As per the ATS/IDSA statement, macrolides are the mainstay of treatment for pulmonary MAC disease.11 Macrolides achieve an increased concentration in the lung, and when used for treatment of pulmonary MAC disease, there is a strong correlation between in vitro susceptibility, in vivo (clinical) response, and the immunomodulating effects of macrolides.31,32 Macrolide-containing regimens have demonstrated efficacy in patients with MAC pulmonary disease33,34; however, macrolide monotherapy should be avoided to prevent the development of resistance.
At the outset, it is critical to establish the objective criteria for determining response and to ensure that the patient understands the goals of the treatment and expectations of the treatment plan. Moreover, experts suggest that due to the possibility of drug intolerance, side effects, and the need for prolonged therapy, a “step ladder” ramping up approach to treatment could be adopted, with gradual introduction of therapy within a short time period; this approach may improve compliance and adherence to treatment.11 If this approach is used, the doses may have to be divided. Patients who are unable to tolerate daily medications, even with dosage adjustment, should be tried on an intermittent treatment regimen. Older female patients frequently require gradual introduction of medications (ie, 1 medication added to the regimen every 1 to 2 weeks) to evaluate tolerance to each medication and medication dose.11 Commonly encountered adverse effects of NTM treatment include intolerance to clarithromycin due to gastrointestinal problems, low body mass index, or age older than 70 years.
After determining that the patient requires therapy, the standard recommended treatment for MAC pulmonary disease includes the following: for most patients with nodular/bronchiectasis disease, a thrice-weekly regimen of clarithromycin (1000 mg) or azithromycin (500 mg), rifampin (600 mg), and ethambutol (25 mg/kg) is recommended. For patients with cavitary MAC pulmonary disease or severe nodular/bronchiectasis disease, the guidelines recommend a daily regimen of clarithromycin (500-1000 mg) or azithromycin (250 mg), rifampin (600 mg) or rifabutin (150–300 mg), and ethambutol (15 mg/kg), with consideration of intravenous (IV) amikacin 3 times/week early in therapy (Table 2).11
The treatment of MAC hypersensitivity-like disease speaks to the controversy of whether this is an inflammatory process, infectious process, or a combination of inflammation and infection. Avoidance of exposure is the mainstay of management. In some cases, steroids are used with or without a short course of anti-MAC therapy (ie, clarithromycin or azithromycin with rifampin and ethambutol).
Prophylaxis for disseminated MAC disease should be given to adults with HIV infection who have a CD4+ count less than 50 cells/μL. Azithromycin 1200 mg/week or clarithromycin 1000 mg/day has proven efficacy, and rifabutin 300 mg/day is also effective but less well tolerated. Rifabutin is more active in vitro against MAC than rifampin, and is used in HIV-positive patients because of drug-drug interaction between antiretroviral drugs and rifampin.
Continue to: Case 1 Continued
Case 1 Continued
The patient is treated with clarithromycin, rifampin, and ethambutol for 1 year, with sputum conversion after 9 months. In the latter part of her treatment, she experiences decreased visual acuity. Treatment is discontinued prematurely after 1 year due to drug toxicity and continued intolerance to drug therapy. The patient remains asymptomatic for 8 months, and then begins to experience mild to moderate hemoptysis, with increasing cough and sputum production associated with postural changes during exercise. Physical examination overall remains unchanged. Three sputum results reveal heavy growth of MAC, and a CT scan of the chest shows a cavitary lesion in the left upper lobe along with the nodular bronchiectasis (Figure 4).
What are the management options at this stage?
Based on this patient’s continued symptoms, progression of radiologic abnormalities, and current culture growth, she requires re-treatment. With the adverse effects associated with ethambutol during the first round of therapy, the drug regimen needs to be modified. Several considerations are relevant at this stage. Relapse rates range from 20% to 30% after treatment with a macrolide-based therapy.11,34 Obtaining a culture-sensitivity profile is imperative in these cases. Of note, treatment should not be discontinued altogether, but instead the toxic agent should be removed from the treatment regimen. Continuing treatment with a 2-drug regimen of clarithromycin and rifampin may be considered in this patient. Re-infection with multiple genotypes may also occur after successful drug therapy, but this is primarily seen in MAC patients with nodular bronchiectasis.34,35 Patients in whom previous therapy has failed, even those with macrolide-susceptible MAC isolates, are less likely to respond to subsequent therapy. Data suggest that intermittent medication dosing is not effective for patients with severe or cavitary disease or in those in whom previous therapy has failed.36 In this case, treatment should include a daily 3-drug therapy, with an injectable thrice-weekly aminoglycoside. Other agents such as linezolid and clofazimine may have to be tried. Cycloserine, ethionamide, and other agents are sometimes used, but their efficacy is unproven and doubtful. Pyrazinamide and isoniazid have no activity against MAC.
Treatment Failure and Drug Resistance
Treatment failure is considered to have occurred if patients have not had a response (microbiologic, clinical, or radiographic) after 6 months of appropriate therapy or had not achieved conversion of sputum to culture-negative after 12 months of appropriate therapy.11 This occurs in about 40% of patients. Multiple factors can interfere with the successful treatment of MAC pulmonary disease, including medication nonadherence, medication side effects or intolerance, lack of response to a medication regimen, or the emergence of a macrolide-resistant or multidrug-resistant strain. Inducible macrolide resistance remains a potential factor.34-36 A number of characteristics of NTM contribute to the poor response to currently used antibiotics: the organisms have a lipid outer membrane and prefer to adhere to surfaces and form biofilms, which makes them relatively impermeable to antibiotics.37 Also, NTM replicate in phagocytic cells, allowing them to subvert normal cellular defense mechanisms. Furthermore, NTM can display colony variants, whereby single colony isolates switch between antibiotic-susceptible and -resistant variants. These factors have also impeded in development of new antibiotics for NTM infection.37
Recent limited approval of amikacin liposomal inhalation suspension (ALIS) for treatment failure and refractory MAC infection in combination with guideline-based antimicrobial therapy (GBT) is a promising addition to the available treatment armamentarium. In a multinational trial, the addition of ALIS to GBT for treatment-refractory MAC lung disease achieved significantly greater culture conversion rates by month 6 than GBT alone, with comparable rates of serious adverse events.38
Is therapeutic drug monitoring recommended during treatment of MAC pulmonary disease?
Treatment failure may also be drug-related, including poor drug penetration into the damaged lung tissue or drug-drug interactions leading to suboptimal drug levels. Peak serum concentrations have been found to be below target ranges in approximately 50% of patients using a macrolide and ethambutol. Concurrent use of rifampin decreases the peak serum concentration of macrolides and quinolones, with acceptable target levels seen in only 18% to 57% of cases. Whether this alters patient outcomes is not clear.39-42 Factors identified as contributing to the poor response to therapy include poor compliance, cavitary disease, previous treatment for MAC pulmonary disease, and a history of chronic obstructive lung disease. Studies by Koh and colleagues40 and van Ingen and colleagues41 with pharmacokinetic and pharmacodynamics data showed that, in patients on MAC treatment with both clarithromycin and rifampicin, plasma levels of clarithromycin were lower than the recommended minimal inhibitory concentrations (MIC) against MAC for that drug. The studies also showed that rifampicin lowered clarithromycin concentrations more than did rifabutin, with the AUC/MIC ratio being suboptimal in nearly half the cases. However, low plasma clarithromycin concentrations did not have any correlation with treatment outcomes, as the peak plasma drug concentrations and the peak plasma drug concentration/MIC ratios did not differ between patients with unfavorable treatment outcomes and those with favorable outcomes. This is further compounded by the fact that macrolides achieve higher levels in lung tissue than in plasma, and hence the significance of low plasma levels is unclear; however, it is postulated that achieving higher drug levels could, in fact, lead to better clinical outcomes. Pending specific well-designed, prospective randomized controlled trials, routine therapeutic drug monitoring is not currently recommended, although some referral centers do this as their practice pattern.
Is surgery an option in this case?
The overall 5-year mortality for MAC pulmonary disease was approximately 28% in a retrospective analysis, with patients with cavitary disease at increased risk for death at 5 years.42 As such, surgery is an option in selected cases as part of adjunctive therapy along with anti-MAC therapy based on mycobacterial sensitivity. Surgery is used as either a curative approach or a “debulking” measure.11 When present, clearly localized disease, especially in the upper lobe, lends itself best to surgical intervention. Surgical resection of a solitary pulmonary nodule due to MAC, in addition to concomitant medical treatment, is recommended. Surgical intervention should be considered early in the course of the disease because it may provide a cure without prolonged treatment and its associated problems, and this approach may lead to early sputum conversion. Surgery should also be considered in patients with macrolide-resistant or multidrug-resistant MAC infection or in those who cannot tolerate the side effects of therapy, provided that the disease is focal and limited. Patients with poor preoperative lung function have poorer outcomes than those with good lung function, and postoperative complications arising from treatment, especially with a right-sided pneumonectomy, tend to occur more frequently in these patients. Thoracic surgery for NTM pulmonary disease must be considered cautiously, as this is associated with significant morbidity and mortality and is best performed at specialized centers that have expertise and experience in this field.43
Continue to: Mycobacterium abscessus Complex
Mycobacterium abscessus Complex
Case Patient 2
A 64-year-old man who is an ex-smoker presents with chronic cough, mild shortness of breath on exertion, low-grade fever, and unintentional weight loss of 10 lb. Physical exam is unremarkable. The patient was diagnosed with immunoglobulin deficiency (low IgM and low IgG4) in 2002, and has been on replacement therapy since then. He also has had multiple episodes of NTM infection, with MAC and M. kansasii infections diagnosed in 2012-2014, which required 18 months of multi-drug antibiotic treatment that resulted in sputum conversion. Pulmonary function testing done on this visit in 2017 shows mild obstructive impairment.
Chest radiograph and CT scan show bilateral bronchiectasis (Figure 5 and Figure 6).
The results of serial sputum microbiology testing performed over the course of 6 months are outlined below:
- 5/2017 (bronchoalveolar lavage): 2+; M. abscessus
- 9/2017 × 2: smear (–); group IV RGM
- 11/2017: smear (–); M. abscessus (> 50 CFU)
- 12/2017: smear (–); M. abscessus (> 50 CFU)
What are the clinical considerations in this patient with multiple NTM infections?
M. abscessus complex was originally described in soft tissue abscesses and skin infections possibly resulting from soil or water contamination. Subspeciation of M. abscessus complex during laboratory testing is critical to facilitate selection of a specific therapeutic approach; treatment decisions are impacted by the presence of an active erm gene and in vitro macrolide sensitivity, which differ between subspecies. The most acceptable classification outlines 3 species in the M. abscessus complex: Mycobacterium abscessus subsp abscessus, Mycobacterium abscessus subsp bolletii (both with an active erm gene responsible for macrolide resistance), and Mycobacterium abscessus subsp massiliense (with an inactive erm gene and therefore susceptible to macrolides).44
RGM typically manifest in skin, soft tissue, and bone, and can cause soft tissue, surgical wound, and catheter-related infections. Although the role of RGM as pulmonary pathogens is unclear, underlying diseases associated with RGM include previously treated mycobacterial disease, coexistent pulmonary diseases with or without MAC, cystic fibrosis, malignancies, and gastroesophageal disorders. M. abscessus is the third most commonly identified respiratory NTM and accounts for the majority (80%) of RGM respiratory isolates. Other NTM reported to cause both lung disease and skin, bone, and joint infections include Mycobacterium simiae, Mycobacterium xenopi, and Mycobacterium malmoense. Ocular granulomatous diseases, such as chorioretinitis and keratitis, have been reported with both RGM and Runyon group III SGM, such as MAC or M. szulgai, following trauma or refractive surgery. These can mimic fungal, herpetic, or amebic keratitis. The pulmonary syndromes associated with multiple culture positivity are seen in elderly women with bronchiectasis or cavitary lung disease and/or associated with gastrointestinal symptoms of acid reflux, with or without achalasia and concomitant lipoid interstitial pneumonia.45
Generally, pulmonary disease progresses slowly, but lung disease attributed to RGM can result in respiratory failure. Thus, RGM should be recognized as a possible cause of chronic mycobacterial lung disease, especially in immunocompromised patients, and respiratory isolates should be assessed carefully. Identification and drug susceptibility testing are essential before initiation of treatment for RGM.
What is the approach to management of M. abscessus pulmonary disease in a patient without cystic fibrosis?
The management of M. abscessus pulmonary infection as a subset of RGM requires a considered step-wise approach. The criteria for diagnosis and threshold for starting treatment are the same as those used in the management of MAC pulmonary disease,11 but the treatment of M. abscessus pulmonary infection is more complex and has lower rates of success and cure. Also, antibiotic treatment presents challenges related to rapid identification of the causative organism, nomenclature, resistance patterns, and tolerance of treatment and side effects. If a source such as catheter, access port, or any surgical site is identified, prompt removal and clearance of the infected site are strongly advised
In the absence of any controlled clinical trials, treatment of RGM is based on in vitro susceptibility testing and expert opinion. As in MAC pulmonary disease, macrolides are the mainstay of treatment, with an induction phase of intravenous antibiotics. Treatment may include a combination of injectable aminoglycosides, imipenem, or cefoxitin and oral drugs such as a macrolide (eg, clarithromycin, azithromycin), doxycycline, fluoroquinolones, trimethoprim/sulfamethoxazole, or linezolid. While antibiotic treatment of M. abscessus pulmonary disease is based on in vitro sensitivity pattern to a greater degree than is treatment of MAC pulmonary disease, this approach has significant practical limitations and hence variable applicability. The final choice of antibiotics is best based on the extended susceptibility results, if available. The presence of an active erm gene on a prolonged growth specimen in M. abscessus subsp abscessus and M. abscessus subsp bolletii precludes the use of a macrolide. In such cases, amikacin, especially in an intravenous form, is the mainstay of treatment based on MIC. Recently, there has been a resurgence in interest in the use of clofazimine in combination with amikacin when treatment is not successful in patients with M. abscessus subsp abscessus or M. bolletii with an active erm gene.45,46 When localized abscess formation is noted, surgery may be the best option, with emphasis on removal of implants and catheters if implicated in RGM infection.
Attention must also be given to confounding pulmonary and associated comorbidities. This includes management of bronchiectasis with appropriately aggressive airway clearance techniques; anti-reflux measures for prevention of micro-aspiration; and management of other comorbid pulmonary conditions, such as chronic obstructive pulmonary disease, pulmonary fibrosis, and sarcoidosis, if applicable. These interventions play a critical role in clearing the M. abscessus infection, preventing progression of disease, and reducing morbidity. The role of immunomodulatory therapy needs to be considered on a regular, ongoing basis. Identification of genetic factors and correction of immune deficiencies may help in managing the infection.
Case Patient 2 Conclusion
The treatment regimen adopted in this case includes a 3-month course of daily intravenous amikacin and imipenem with oral azithromycin, followed by a continuation phase of azithromycin with clofazimine and linezolid. Airway clearance techniques such as Vest/Acapella/CPT are intensified and monthly intravenous immunoglobulin therapy is continued. The patient responds to treatment, with resolution of his clinical symptoms and reduction in the colony count of M. abscessus in the sputum.
Summary
NTM are ubiquitous in the environment, and NTM infection has variable manifestations, especially in patients with no recognizable immune impairments. Underlying comorbid conditions with bronchiectasis complicate its management. Treatment strategies must be individualized based on degree of involvement, associated comorbidities, immune deficiencies, goals of therapy, outcome-based risk-benefit ratio assessment, and patient engagement and expectations. In diffuse pulmonary disease, drug treatment remains difficult due to poor match of in vitro and in vivo culture sensitivity, side effects of medications, and high failure rates. When a localized resectable foci of infection is identified, especially in RGM disease, surgical treatment may be the best approach in selected patients, but it must be performed in centers with expertise and experience in this field.
Nontuberculous mycobacterial pulmonary disease is a broad term for a group of pulmonary disorders caused and characterized by exposure to environmental mycobacteria other than those belonging to the Mycobacterium tuberculosis complex and Mycobacterium leprae. Mycobacteria are aerobic, nonmotile organisms that appear positive with acid-fast alcohol stains. Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and have been recovered from domestic and natural water sources, soil, and food products, and from around livestock, cattle, and wildlife.1-3 To date, no evidence exists of human-to-human or animal-to-human transmission of NTM in the general population. Infections in humans are usually acquired from environmental exposures, although the specific source of infection cannot always be identified. Similarly, the mode of infection with NTM has not been established with certainty, but it is highly likely that the organism is implanted, ingested, aspirated, or inhaled. Aerosolization of droplets associated with use of bathroom showerheads and municipal water sources and soil contamination are some of the factors associated with the transmission of infection. Proven routes of transmission include showerheads and potting soil dust.2,3
NTM pulmonary disease occurs in individuals with or without comorbid conditions such as bronchiectasis, chronic obstructive pulmonary disease, pulmonary fibrosis, or structural lung diseases. Slender, middle-aged or elderly white females with marfanoid body habitus, with or without apparent immune or genetic disorders, showing impaired airway and mucus clearance present with this infection as a form of underlying bronchiectasis (Lady Windermere syndrome). It is unclear why NTM infections and escalation to clinical disease occur in certain individuals. Many risk factors, including inherited and acquired defects of host immune response (eg, cystic fibrosis trait and α1 antitrypsin deficiency), have been associated with increased susceptibility to NTM infections.4
NTM infection can lead to chronic symptoms, frequent exacerbations, progressive functional and structural lung destruction, and impaired quality of life, and is associated with an increased risk of hospitalization and higher 5-year all-cause mortality. As such, NTM disease is drawing increasing attention at the clinical, academic, and research levels.5 This case-based review outlines the clinical features of NTM infection, with a focus on the challenges in diagnosis, treatment, and management of NTM pulmonary disease. The cases use Mycobacterium avium complex (MAC), a slow-growing mycobacteria (SGM), and Mycobacterium abscessus, a rapidly growing mycobacteria (RGM), as prototypes in a non–cystic fibrosis, non-HIV clinical setting.
Epidemiology
Of the almost 200 isolated species of NTM, the most prevalent pathogens for respiratory disease in the United States are MAC, Mycobacterium kansasii, and M. abscessus. MAC accounts for more than 80% of cases of NTM respiratory disease in the United States.6 The prevalence of NTM disease is increasing at a rate of about 8% each year, with 75,000 to 105,000 patients diagnosed with NTM lung disease in the United States annually. NTM infections in the United States are increasing among patients aged 65 years and older, a population that is expected to nearly double by 2030.7,8
Isolation and prevalence of many NTM species are higher in certain geographic areas of the United States, especially in the southeast. The US coastal regions have a higher prevalence of NTM pulmonary disease, and account for 70% of NTM cases in the United States each year. Half of patients diagnosed with NTM lung disease reside in 7 states: Florida, New York, Texas, California, Pennsylvania, New Jersey, and Ohio, with 1 in 7 residing in Florida. Three parishes in Louisiana are among the top 10 counties with the highest prevalence in United States. The prevalence of NTM infection–associated hospitalizations is increasing worldwide as well. Co-infection with tuberculosis and multiple NTMs in individual patients has been observed clinically and documented in patients with and without HIV.9,10
It is not clear why the prevalence of NTM pulmonary disease is increasing, but there may be several contributing factors: (1) an increased awareness and identification of NTM infection sources in the environment; (2) an expanding cohort of immunocompromised individuals with exogenous or endogenous immune deficiencies; (3) availability of improved diagnostic techniques, such as use of high-performance liquid chromatography (HPLC), DNA probes, and gene sequencing; and (4) an increased awareness of the morbidity and mortality associated with NTM pulmonary disease. However, it is important to recognize that to best understand the clinical relevance of epidemiologic studies based on laboratory diagnosis and identification, the findings must be evaluated by correlating them with the microbiological and other clinical criteria established by the American Thoracic Society (ATS)/Infectious Diseases Society of America (IDSA) guidelines.11
Continue to: Mycobacterium avium Complex
Mycobacterium avium Complex
Case Patient 1
A 48-year-old woman who has never smoked and has no past medical problems, except seasonal allergic rhinitis and “colds and flu-like illness” once or twice a year, is evaluated for a chronic lingering cough with occasional sputum production. The patient denies any other chronic symptoms and is otherwise active. Physical examination reveals no specific findings except mild pectus excavatum and mild scoliosis. Body mass index is 22 kg/m2. Chest radiograph shows nonspecific increased markings in the lower zones. Computed tomography (CT) scan of the chest reveals minimal nodular and cylindrical bronchiectasis in both lungs (Figure 1). No previous radiographs are available for comparison. The patient is HIV-negative. Sputum tests reveal normal flora, and both fungus and acid-fast bacilli smear are negative. Culture for mycobacteria shows scanty growth of MAC in 1 specimen.
What is the clinical presentation of MAC pulmonary disease?
Among NTM, MAC is the most common cause of pulmonary disease worldwide.6 MAC primarily includes 2 species: M. avium and Mycobacterium intracellulare. M. avium is the more important pathogen in disseminated disease, whereas M. intracellulare is the more common respiratory pathogen.11 These organisms are genetically similar and generally not differentiated in the clinical microbiology laboratory, although there are isolated reports in the literature suggesting differences in prevalence, presentation, and prognosis in M. avium infection versus M. intracellulare infection.12
Three major disease syndromes are produced by MAC in humans: pulmonary disease, usually in adults whose systemic immunity is intact; disseminated disease, usually in patients with advanced HIV infection; and cervical lymphadenitis.13 Pulmonary disease caused by MAC may take on 1 of several clinically different forms, including asymptomatic “colonization” or persistent minimal infection without obvious clinical significance; endobronchial involvement; progressive pulmonary disease with radiographic and clinical deterioration and nodular bronchiectasis or cavitary lung disease; hypersensitivity pneumonitis; or persistent, overwhelming mycobacterial growth with symptomatic manifestations, often in a lung with underlying damage due to either chronic obstructive lung disease or pulmonary fibrosis (Table 1).14
Cavitary Disease
The traditionally recognized presentation of MAC lung disease has been apical cavitary lung disease in men in their late 40s and early 50s who have a history of cigarette smoking, and frequently, excessive alcohol use. If left untreated, or in the case of erratic treatment or macrolide drug resistance, this form of disease is generally progressive within a relatively short time and can result in extensive cavitary lung destruction and progressive respiratory failure.15
Nodular Bronchiectasis
The more common presentation of MAC lung disease, which is outlined in the case described here, is interstitial nodular infiltrates, frequently involving the right middle lobe or lingula and predominantly occurring in postmenopausal, nonsmoking white women. This is sometimes labelled “Lady Windermere syndrome.” These patients with M. avium infection appear to have similar clinical characteristics and body types, including lean build, scoliosis, pectus excavatum, and mitral valve prolapse.16,17 The mechanism by which this body morphotype predisposes to pulmonary mycobacterial infection is not defined, but ineffective mucociliary clearance is a possible explanation. Evidence suggests that some patients may be predisposed to NTM lung disease because of preexisting bronchiectasis. Some potential etiologies of bronchiectasis in this population include chronic sinusitis, gastroesophageal reflux with chronic aspiration, α1 antitrypsin deficiency, and cystic fibrosis genetic traits and mutations.18 Risk factors for increased morbidity and mortality include the development of cavitary disease, age, weight loss, lower body mass index, and other comorbid conditions.
This form of disease, termed nodular bronchiectasis, tends to have a much slower progression than cavitary disease, such that long-term follow-up (months to years) may be necessary to demonstrate clinical or radiographic changes.11 The radiographic term “tree-in-bud” has been used to describe what may reflect inflammatory changes, including bronchiolitis. High-resolution CT scans of the chest are especially helpful for diagnosing this pattern of MAC lung disease, as bronchiectasis and small nodules may not be easily discernible on plain chest radiograph. The nodular/bronchiectasis radiographic pattern can also be seen with other NTM pathogens, including M. abscessus, Mycobacterium simiae, and M. kansasii. Solitary nodules and dense consolidation have also been described. Pleural effusions are uncommon, but reactive pleural thickening is frequently seen. Co-pathogens may be isolated from culture, including Pseudomonas aeruginosa, Staphylococcus aureus, and, occasionally, other NTM such as M. abscessus or Mycobacterium chelonae.19-21
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis, initially described in patients who were exposed to hot tubs, mimics allergic hypersensitivity pneumonitis, with respiratory symptoms and culture/tissue identification of MAC or sometimes other NTM. It is unclear whether hypersensitivity pneumonitis is an inflammatory process, an infection, or both, and opinion regarding the need for specific antibiotic treatment is divided.11,22 However, avoidance of exposure is prudent and recommended.
Disseminated Disease
Disseminated NTM disease is associated with very low CD4+ lymphocyte counts and is seen in approximately 5% of patients with HIV infection.23-25 Although disseminated NTM disease is rarely seen in immunosuppressed patients without HIV infection, it has been reported in patients who have undergone renal or cardiac transplant, patients on long-term corticosteroid therapy, and those with leukemia or lymphoma. More than 90% of infections are caused by MAC; other potential pathogens include M. kansasii, M. chelonae, M. abscessus, and Mycobacterium haemophilum. Although seen less frequently since the advent of highly active antiretroviral therapy, disseminated infection can develop progressively from an apparently indolent or localized infection or a respiratory or gastrointestinal source. Signs and symptoms of disseminated infection (specifically MAC-associated disease) are nonspecific and include fever, night sweats, weight loss, and abdominal tenderness. Disseminated MAC disease occurs primarily in patients with more advanced HIV disease (CD4+ count typically < 50 cells/μL). Clinically, disseminated MAC manifests as intermittent or persistent fever, constitutional symptoms with organomegaly and organ-specific abnormalities (eg, anemia, neutropenia from bone marrow involvement, adenopathy, hepatosplenomegaly), and elevations of liver enzymes or lung infiltrates from pulmonary involvement.
Continue to: What are the criteria for diagnosing NTM pulmonary disease?
What are the criteria for diagnosing NTM pulmonary disease?
The diagnosis of NTM disease is based on clinical, radiologic, and mycobacterial correlation with good communication between the experts in this field. The ATS/IDSA criteria for diagnosing NTM lung disease are shown in Figure 2. These criteria best apply to MAC, M. kansasii, and M. abscessus, but are also clinically applied to other NTM respiratory pathogens. The diagnosis of MAC infection is most readily established by culture of blood, bone marrow, respiratory secretions/fluid, or tissue specimens from suspected sites of involvement. Due to erratic shedding of MAC into the respiratory secretions in patients with nodular bronchiectasis, as compared to those with the cavitary form of the disease, sputum may be intermittently positive, with variable colony counts and polyclonal infections.12 Prior to the advent of high-resolution CT, isolation of MAC organisms from the sputum of such patients was frequently dismissed as colonization.
Mycobacterial Testing
Because of the nonspecific symptoms and lack of diagnostic specificity of chest imaging, the diagnosis of NTM lung disease requires microbiologic confirmation. Specimens sent to the laboratory for identification of NTM must be handled with care to prevent contamination and false-positive results. Transport media and preservatives should be avoided, and transportation of the specimens should be prompt. These measures will prevent bacterial overgrowth. Furthermore, the yield of NTM may be affected if the patient has used antibiotics, such as macrolides and fluoroquinolones, prior to obtaining the specimen.
NTM should be identified at the species and subspecies level, although this is not practical in community practice settings. The preferred staining procedure in the laboratory is the fluorochrome method. Some species require special growth conditions and/or lower incubation temperatures, and other identification methods may have to be employed, such as DNA probes, polymerase chain reaction genotyping, nucleic acid sequence determination, and high-performance liquid chromatography. As a gold standard, clinical specimens for mycobacterial cultures should be inoculated onto 1 or more solid media (eg, Middlebrook 7H11 media and/or Lowenstein-Jensen media, the former of which is the preferred medium for NTM) and into a liquid medium (eg, BACTEC 12B broth or Mycobacteria growth indicator tube broth). Growth of visible colonies on solid media typically requires 2 to 4 weeks, but liquid media (eg, the radiometric BACTEC system), used as a supplementary and not as an exclusive test, usually produce results within 10 to 14 days. Furthermore, even after initial growth, identification of specific isolates based on the growth characteristics on solid media requires additional time. Use of specific nucleic acid probes for MAC and M. kansasii and HPLC testing of mycolic acid patterns in acid-fast bacilli smear–positive specimens can reduce the turnaround time of specific identification of a primary culture–positive sample. However, HPLC is not sufficient for definitive identification of many NTM species, including the RGM. Other newer techniques, including 16S ribosomal DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism analysis, also allow NTM to be identified and speciated more reliably and rapidly from clinical specimens.
Cost and other practical considerations limit widespread adoption of these techniques. However, the recognition that M. abscessus can be separated into more than 1 subspecies, and that there are important prognostic implications of that separation, lends urgency to the broader adoption of newer molecular techniques in the mycobacteriology laboratory. Susceptibility testing is based on the broth microdilution method; RGM usually grow within 7 days of subculture, and the laboratory time to culture is a helpful hint, although not necessarily specific. Recognizing the morphology of mycobacterial colony growth may also be helpful in identification.
Are skin tests helpful in diagnosing NTM infection?
Tuberculin skin testing remains a nonspecific marker of mycobacterial infection and does not help in further elucidating NTM infection. However, epidemiologic and laboratory studies with well-characterized antigens have shown that dual skin testing with tuberculosis- versus NTM-derived tuberculin can discriminate between prior NTM and prior tuberculosis disease. Species-specific skin test antigens are not commercially available and are not helpful in the diagnosis of NTM disease because of cross-reactivity of M. tuberculosis and some NTM. However, increased prevalence of NTM sensitization based on purified protein derivative testing has been noted in a recent survey, which is consistent with an observed increase in the rates of NTM infections, specifically MAC, in the United States.26,27
Interferon-gamma release assays (IGRAs) are now being used as an alternative to tuberculin skin testing to diagnose M. tuberculosis infection. Certain NTM species also contain gene sequences that encode for ESAT-6 or CFP-10 antigens used in the IGRAs, and hence, yield a positive IGRA test. These include M. marinum, M. szulgai, and M. kansasii.28,29 However, MAC organisms do not produce positive results on assays that use these antigens.
Continue to: What is the approach to management of NTM pulmonary disease?
What is the approach to management of NTM pulmonary disease?
The correlation of symptoms with radiographic and microbiologic evidence is essential to categorize the disease and determine the need for therapy. Making the diagnosis of NTM lung disease does not necessitate the institution of therapy. The decision to treat should be weighed against potential risks and benefits to the individual patient based on symptomatic, radiographic, and microbiologic criteria, as well as underlying systemic or pulmonary immune status. In the absence of evidence of clinical, radiologic, or mycobacterial progression of disease, pursuing airway clearance therapy and clinical surveillance without initiating specific anti-MAC therapy is a reasonable option.11 Identifying the sustained presence of NTM infection, especially MAC, in a patient with underlying clinical and radiographic evidence of bronchiectasis is of value in determining comprehensive treatment and management strategies. Close observation is indicated if the decision not to treat is made. If treatment is initiated, comprehensive management includes long-term follow-up with periodic bacteriologic surveillance, watching for drug toxicity and drug-drug interactions, ensuring adherence and compliance to treatment, and managing comorbidity.
The Bronchiectasis Severity Index is a useful clinical predictive tool that identifies patients at risk of future mortality, hospitalization, and exacerbations and can be used to evaluate the need for specific treatment.30 The index is based on dyspnea score, lung function tests, colonization of pathogens, and extent of disease.
Case 1 Continued
After approximately 2 months of observation and symptomatic treatment, without specific antibiotic therapy, the patient’s symptoms continue. She now develops intermittent hemoptysis. Repeat sputum studies reveal moderate growth of M. avium. A follow-up CT scan shows progression of disease, with an increase in the tree-in-bud pattern (Figure 3).
What treatment protocols are recommended for MAC pulmonary disease?
As per the ATS/IDSA statement, macrolides are the mainstay of treatment for pulmonary MAC disease.11 Macrolides achieve an increased concentration in the lung, and when used for treatment of pulmonary MAC disease, there is a strong correlation between in vitro susceptibility, in vivo (clinical) response, and the immunomodulating effects of macrolides.31,32 Macrolide-containing regimens have demonstrated efficacy in patients with MAC pulmonary disease33,34; however, macrolide monotherapy should be avoided to prevent the development of resistance.
At the outset, it is critical to establish the objective criteria for determining response and to ensure that the patient understands the goals of the treatment and expectations of the treatment plan. Moreover, experts suggest that due to the possibility of drug intolerance, side effects, and the need for prolonged therapy, a “step ladder” ramping up approach to treatment could be adopted, with gradual introduction of therapy within a short time period; this approach may improve compliance and adherence to treatment.11 If this approach is used, the doses may have to be divided. Patients who are unable to tolerate daily medications, even with dosage adjustment, should be tried on an intermittent treatment regimen. Older female patients frequently require gradual introduction of medications (ie, 1 medication added to the regimen every 1 to 2 weeks) to evaluate tolerance to each medication and medication dose.11 Commonly encountered adverse effects of NTM treatment include intolerance to clarithromycin due to gastrointestinal problems, low body mass index, or age older than 70 years.
After determining that the patient requires therapy, the standard recommended treatment for MAC pulmonary disease includes the following: for most patients with nodular/bronchiectasis disease, a thrice-weekly regimen of clarithromycin (1000 mg) or azithromycin (500 mg), rifampin (600 mg), and ethambutol (25 mg/kg) is recommended. For patients with cavitary MAC pulmonary disease or severe nodular/bronchiectasis disease, the guidelines recommend a daily regimen of clarithromycin (500-1000 mg) or azithromycin (250 mg), rifampin (600 mg) or rifabutin (150–300 mg), and ethambutol (15 mg/kg), with consideration of intravenous (IV) amikacin 3 times/week early in therapy (Table 2).11
The treatment of MAC hypersensitivity-like disease speaks to the controversy of whether this is an inflammatory process, infectious process, or a combination of inflammation and infection. Avoidance of exposure is the mainstay of management. In some cases, steroids are used with or without a short course of anti-MAC therapy (ie, clarithromycin or azithromycin with rifampin and ethambutol).
Prophylaxis for disseminated MAC disease should be given to adults with HIV infection who have a CD4+ count less than 50 cells/μL. Azithromycin 1200 mg/week or clarithromycin 1000 mg/day has proven efficacy, and rifabutin 300 mg/day is also effective but less well tolerated. Rifabutin is more active in vitro against MAC than rifampin, and is used in HIV-positive patients because of drug-drug interaction between antiretroviral drugs and rifampin.
Continue to: Case 1 Continued
Case 1 Continued
The patient is treated with clarithromycin, rifampin, and ethambutol for 1 year, with sputum conversion after 9 months. In the latter part of her treatment, she experiences decreased visual acuity. Treatment is discontinued prematurely after 1 year due to drug toxicity and continued intolerance to drug therapy. The patient remains asymptomatic for 8 months, and then begins to experience mild to moderate hemoptysis, with increasing cough and sputum production associated with postural changes during exercise. Physical examination overall remains unchanged. Three sputum results reveal heavy growth of MAC, and a CT scan of the chest shows a cavitary lesion in the left upper lobe along with the nodular bronchiectasis (Figure 4).
What are the management options at this stage?
Based on this patient’s continued symptoms, progression of radiologic abnormalities, and current culture growth, she requires re-treatment. With the adverse effects associated with ethambutol during the first round of therapy, the drug regimen needs to be modified. Several considerations are relevant at this stage. Relapse rates range from 20% to 30% after treatment with a macrolide-based therapy.11,34 Obtaining a culture-sensitivity profile is imperative in these cases. Of note, treatment should not be discontinued altogether, but instead the toxic agent should be removed from the treatment regimen. Continuing treatment with a 2-drug regimen of clarithromycin and rifampin may be considered in this patient. Re-infection with multiple genotypes may also occur after successful drug therapy, but this is primarily seen in MAC patients with nodular bronchiectasis.34,35 Patients in whom previous therapy has failed, even those with macrolide-susceptible MAC isolates, are less likely to respond to subsequent therapy. Data suggest that intermittent medication dosing is not effective for patients with severe or cavitary disease or in those in whom previous therapy has failed.36 In this case, treatment should include a daily 3-drug therapy, with an injectable thrice-weekly aminoglycoside. Other agents such as linezolid and clofazimine may have to be tried. Cycloserine, ethionamide, and other agents are sometimes used, but their efficacy is unproven and doubtful. Pyrazinamide and isoniazid have no activity against MAC.
Treatment Failure and Drug Resistance
Treatment failure is considered to have occurred if patients have not had a response (microbiologic, clinical, or radiographic) after 6 months of appropriate therapy or had not achieved conversion of sputum to culture-negative after 12 months of appropriate therapy.11 This occurs in about 40% of patients. Multiple factors can interfere with the successful treatment of MAC pulmonary disease, including medication nonadherence, medication side effects or intolerance, lack of response to a medication regimen, or the emergence of a macrolide-resistant or multidrug-resistant strain. Inducible macrolide resistance remains a potential factor.34-36 A number of characteristics of NTM contribute to the poor response to currently used antibiotics: the organisms have a lipid outer membrane and prefer to adhere to surfaces and form biofilms, which makes them relatively impermeable to antibiotics.37 Also, NTM replicate in phagocytic cells, allowing them to subvert normal cellular defense mechanisms. Furthermore, NTM can display colony variants, whereby single colony isolates switch between antibiotic-susceptible and -resistant variants. These factors have also impeded in development of new antibiotics for NTM infection.37
Recent limited approval of amikacin liposomal inhalation suspension (ALIS) for treatment failure and refractory MAC infection in combination with guideline-based antimicrobial therapy (GBT) is a promising addition to the available treatment armamentarium. In a multinational trial, the addition of ALIS to GBT for treatment-refractory MAC lung disease achieved significantly greater culture conversion rates by month 6 than GBT alone, with comparable rates of serious adverse events.38
Is therapeutic drug monitoring recommended during treatment of MAC pulmonary disease?
Treatment failure may also be drug-related, including poor drug penetration into the damaged lung tissue or drug-drug interactions leading to suboptimal drug levels. Peak serum concentrations have been found to be below target ranges in approximately 50% of patients using a macrolide and ethambutol. Concurrent use of rifampin decreases the peak serum concentration of macrolides and quinolones, with acceptable target levels seen in only 18% to 57% of cases. Whether this alters patient outcomes is not clear.39-42 Factors identified as contributing to the poor response to therapy include poor compliance, cavitary disease, previous treatment for MAC pulmonary disease, and a history of chronic obstructive lung disease. Studies by Koh and colleagues40 and van Ingen and colleagues41 with pharmacokinetic and pharmacodynamics data showed that, in patients on MAC treatment with both clarithromycin and rifampicin, plasma levels of clarithromycin were lower than the recommended minimal inhibitory concentrations (MIC) against MAC for that drug. The studies also showed that rifampicin lowered clarithromycin concentrations more than did rifabutin, with the AUC/MIC ratio being suboptimal in nearly half the cases. However, low plasma clarithromycin concentrations did not have any correlation with treatment outcomes, as the peak plasma drug concentrations and the peak plasma drug concentration/MIC ratios did not differ between patients with unfavorable treatment outcomes and those with favorable outcomes. This is further compounded by the fact that macrolides achieve higher levels in lung tissue than in plasma, and hence the significance of low plasma levels is unclear; however, it is postulated that achieving higher drug levels could, in fact, lead to better clinical outcomes. Pending specific well-designed, prospective randomized controlled trials, routine therapeutic drug monitoring is not currently recommended, although some referral centers do this as their practice pattern.
Is surgery an option in this case?
The overall 5-year mortality for MAC pulmonary disease was approximately 28% in a retrospective analysis, with patients with cavitary disease at increased risk for death at 5 years.42 As such, surgery is an option in selected cases as part of adjunctive therapy along with anti-MAC therapy based on mycobacterial sensitivity. Surgery is used as either a curative approach or a “debulking” measure.11 When present, clearly localized disease, especially in the upper lobe, lends itself best to surgical intervention. Surgical resection of a solitary pulmonary nodule due to MAC, in addition to concomitant medical treatment, is recommended. Surgical intervention should be considered early in the course of the disease because it may provide a cure without prolonged treatment and its associated problems, and this approach may lead to early sputum conversion. Surgery should also be considered in patients with macrolide-resistant or multidrug-resistant MAC infection or in those who cannot tolerate the side effects of therapy, provided that the disease is focal and limited. Patients with poor preoperative lung function have poorer outcomes than those with good lung function, and postoperative complications arising from treatment, especially with a right-sided pneumonectomy, tend to occur more frequently in these patients. Thoracic surgery for NTM pulmonary disease must be considered cautiously, as this is associated with significant morbidity and mortality and is best performed at specialized centers that have expertise and experience in this field.43
Continue to: Mycobacterium abscessus Complex
Mycobacterium abscessus Complex
Case Patient 2
A 64-year-old man who is an ex-smoker presents with chronic cough, mild shortness of breath on exertion, low-grade fever, and unintentional weight loss of 10 lb. Physical exam is unremarkable. The patient was diagnosed with immunoglobulin deficiency (low IgM and low IgG4) in 2002, and has been on replacement therapy since then. He also has had multiple episodes of NTM infection, with MAC and M. kansasii infections diagnosed in 2012-2014, which required 18 months of multi-drug antibiotic treatment that resulted in sputum conversion. Pulmonary function testing done on this visit in 2017 shows mild obstructive impairment.
Chest radiograph and CT scan show bilateral bronchiectasis (Figure 5 and Figure 6).
The results of serial sputum microbiology testing performed over the course of 6 months are outlined below:
- 5/2017 (bronchoalveolar lavage): 2+; M. abscessus
- 9/2017 × 2: smear (–); group IV RGM
- 11/2017: smear (–); M. abscessus (> 50 CFU)
- 12/2017: smear (–); M. abscessus (> 50 CFU)
What are the clinical considerations in this patient with multiple NTM infections?
M. abscessus complex was originally described in soft tissue abscesses and skin infections possibly resulting from soil or water contamination. Subspeciation of M. abscessus complex during laboratory testing is critical to facilitate selection of a specific therapeutic approach; treatment decisions are impacted by the presence of an active erm gene and in vitro macrolide sensitivity, which differ between subspecies. The most acceptable classification outlines 3 species in the M. abscessus complex: Mycobacterium abscessus subsp abscessus, Mycobacterium abscessus subsp bolletii (both with an active erm gene responsible for macrolide resistance), and Mycobacterium abscessus subsp massiliense (with an inactive erm gene and therefore susceptible to macrolides).44
RGM typically manifest in skin, soft tissue, and bone, and can cause soft tissue, surgical wound, and catheter-related infections. Although the role of RGM as pulmonary pathogens is unclear, underlying diseases associated with RGM include previously treated mycobacterial disease, coexistent pulmonary diseases with or without MAC, cystic fibrosis, malignancies, and gastroesophageal disorders. M. abscessus is the third most commonly identified respiratory NTM and accounts for the majority (80%) of RGM respiratory isolates. Other NTM reported to cause both lung disease and skin, bone, and joint infections include Mycobacterium simiae, Mycobacterium xenopi, and Mycobacterium malmoense. Ocular granulomatous diseases, such as chorioretinitis and keratitis, have been reported with both RGM and Runyon group III SGM, such as MAC or M. szulgai, following trauma or refractive surgery. These can mimic fungal, herpetic, or amebic keratitis. The pulmonary syndromes associated with multiple culture positivity are seen in elderly women with bronchiectasis or cavitary lung disease and/or associated with gastrointestinal symptoms of acid reflux, with or without achalasia and concomitant lipoid interstitial pneumonia.45
Generally, pulmonary disease progresses slowly, but lung disease attributed to RGM can result in respiratory failure. Thus, RGM should be recognized as a possible cause of chronic mycobacterial lung disease, especially in immunocompromised patients, and respiratory isolates should be assessed carefully. Identification and drug susceptibility testing are essential before initiation of treatment for RGM.
What is the approach to management of M. abscessus pulmonary disease in a patient without cystic fibrosis?
The management of M. abscessus pulmonary infection as a subset of RGM requires a considered step-wise approach. The criteria for diagnosis and threshold for starting treatment are the same as those used in the management of MAC pulmonary disease,11 but the treatment of M. abscessus pulmonary infection is more complex and has lower rates of success and cure. Also, antibiotic treatment presents challenges related to rapid identification of the causative organism, nomenclature, resistance patterns, and tolerance of treatment and side effects. If a source such as catheter, access port, or any surgical site is identified, prompt removal and clearance of the infected site are strongly advised
In the absence of any controlled clinical trials, treatment of RGM is based on in vitro susceptibility testing and expert opinion. As in MAC pulmonary disease, macrolides are the mainstay of treatment, with an induction phase of intravenous antibiotics. Treatment may include a combination of injectable aminoglycosides, imipenem, or cefoxitin and oral drugs such as a macrolide (eg, clarithromycin, azithromycin), doxycycline, fluoroquinolones, trimethoprim/sulfamethoxazole, or linezolid. While antibiotic treatment of M. abscessus pulmonary disease is based on in vitro sensitivity pattern to a greater degree than is treatment of MAC pulmonary disease, this approach has significant practical limitations and hence variable applicability. The final choice of antibiotics is best based on the extended susceptibility results, if available. The presence of an active erm gene on a prolonged growth specimen in M. abscessus subsp abscessus and M. abscessus subsp bolletii precludes the use of a macrolide. In such cases, amikacin, especially in an intravenous form, is the mainstay of treatment based on MIC. Recently, there has been a resurgence in interest in the use of clofazimine in combination with amikacin when treatment is not successful in patients with M. abscessus subsp abscessus or M. bolletii with an active erm gene.45,46 When localized abscess formation is noted, surgery may be the best option, with emphasis on removal of implants and catheters if implicated in RGM infection.
Attention must also be given to confounding pulmonary and associated comorbidities. This includes management of bronchiectasis with appropriately aggressive airway clearance techniques; anti-reflux measures for prevention of micro-aspiration; and management of other comorbid pulmonary conditions, such as chronic obstructive pulmonary disease, pulmonary fibrosis, and sarcoidosis, if applicable. These interventions play a critical role in clearing the M. abscessus infection, preventing progression of disease, and reducing morbidity. The role of immunomodulatory therapy needs to be considered on a regular, ongoing basis. Identification of genetic factors and correction of immune deficiencies may help in managing the infection.
Case Patient 2 Conclusion
The treatment regimen adopted in this case includes a 3-month course of daily intravenous amikacin and imipenem with oral azithromycin, followed by a continuation phase of azithromycin with clofazimine and linezolid. Airway clearance techniques such as Vest/Acapella/CPT are intensified and monthly intravenous immunoglobulin therapy is continued. The patient responds to treatment, with resolution of his clinical symptoms and reduction in the colony count of M. abscessus in the sputum.
Summary
NTM are ubiquitous in the environment, and NTM infection has variable manifestations, especially in patients with no recognizable immune impairments. Underlying comorbid conditions with bronchiectasis complicate its management. Treatment strategies must be individualized based on degree of involvement, associated comorbidities, immune deficiencies, goals of therapy, outcome-based risk-benefit ratio assessment, and patient engagement and expectations. In diffuse pulmonary disease, drug treatment remains difficult due to poor match of in vitro and in vivo culture sensitivity, side effects of medications, and high failure rates. When a localized resectable foci of infection is identified, especially in RGM disease, surgical treatment may be the best approach in selected patients, but it must be performed in centers with expertise and experience in this field.
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1. Johnson MM, Odell JA. Nontuberculous mycobacterial pulmonary infections. J Thorac Dis. 2014;6:210-220.
2. Falkinham JO III. Environmental sources of NTM. Clin Chest Med. 2015;36:35-41.
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Chronic cough in COPD linked to more severe disease
, according to research published in CHEST.
The results indicate “that chronic cough in individuals with COPD is associated with a more severe disease phenotype, which could be helpful for stratifying management of COPD in the future,” wrote Eskild Landt, PhD, a research assistant at Zealand University Hospital in Køge, Denmark, and colleagues.
A study by published in the Journal of Allergy and Clinical Immunology: In Practice (2019;7[6]:1783-92.e8) indicated that in patients with asthma, chronic cough was associated with worse respiratory symptoms, more health care utilization, decreased lung function, and increased inflammatory markers in blood. Dr. Landt and colleagues hypothesized that patients with COPD and chronic cough had a similar pattern of disease severity.
To test their hypothesis, they identified individuals with COPD and chronic cough among 43,271 participants in the Copenhagen General Population Study, a population-based cohort study. The researchers defined COPD as a ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) of less than 0.70 in individuals without asthma. Consecutive individuals answered questions about chronic cough, which was defined as a cough lasting more than 8 weeks, and responded to the Leicester Cough Questionnaire. They also underwent a physical health examination, including prebronchodilatory spirometry, and gave blood for biochemical analyses. The blood was analyzed for high-sensitive C-reactive protein, fibrinogen, leukocytes, eosinophils, neutrophils, and immunoglobulin E (i.e., inflammatory biomarkers).
Dr. Landt and colleagues identified 8,181 patients (19% of the population) with COPD, 796 (10%) of whom had chronic cough. Of the 33,364 participants without COPD, 1,585 (5%) had chronic cough. For patients with COPD and chronic cough, median total Leicester Cough Questionnaire score was 17.7, corresponding to 5.9 for the physical domain, 5.6 for the psychological domain, and 6.3 for the social domain.
Among participants with COPD, those with chronic cough had higher rates of sputum production (60% versus 8%), wheezing (46% versus 14%), dyspnea (66% versus 38%), chest pain or tightness (9% versus 4%), nighttime dyspnea (8% versus 3%), episodes of acute bronchitis or pneumonias in the past 10 years (45% versus 25%), and general practitioner visits in the past 12 months (53% versus 37%). In addition, these participants had lower FEV1% of predicted (81% versus 89%), lower ratio of FEV1 to FVC (0.64 versus 0.66), and higher levels of high-sensitive C-reactive protein, fibrinogen, leukocytes, neutrophils, eosinophils, and immunoglobulin E in blood.
“To our knowledge, this is the first study reporting Leicester Cough Questionnaire score for randomly selected individuals with COPD from a general population setting,” wrote Dr. Landt and colleagues. The study’s strengths include its randomly chosen population-based sample and investigator blinding to disease status and clinical outcome, they added. Some patients with the most severe types of COPD and chronic cough may not have attended the physical examination and participated in the study, however, and this factor could have biased the results. Furthermore, nearly the entire sample was white, so the results may not be generalizable to other ethnicities. “That said, we are not aware of results to suggest that our findings should not be relevant to individuals of all races,” wrote the investigators.
The study was funded by the private Lundbeck Foundation, as well as by the Danish Lung Association and the Danish Cancer Society. Several authors reported receiving grants and fees from AstraZeneca, GlaxoSmithKline, and Novartis that were unrelated to the study.
SOURCE: Landt E et al. CHEST. 2020 Jan 24. doi: 10.1016/j.chest.2019.12.038.
, according to research published in CHEST.
The results indicate “that chronic cough in individuals with COPD is associated with a more severe disease phenotype, which could be helpful for stratifying management of COPD in the future,” wrote Eskild Landt, PhD, a research assistant at Zealand University Hospital in Køge, Denmark, and colleagues.
A study by published in the Journal of Allergy and Clinical Immunology: In Practice (2019;7[6]:1783-92.e8) indicated that in patients with asthma, chronic cough was associated with worse respiratory symptoms, more health care utilization, decreased lung function, and increased inflammatory markers in blood. Dr. Landt and colleagues hypothesized that patients with COPD and chronic cough had a similar pattern of disease severity.
To test their hypothesis, they identified individuals with COPD and chronic cough among 43,271 participants in the Copenhagen General Population Study, a population-based cohort study. The researchers defined COPD as a ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) of less than 0.70 in individuals without asthma. Consecutive individuals answered questions about chronic cough, which was defined as a cough lasting more than 8 weeks, and responded to the Leicester Cough Questionnaire. They also underwent a physical health examination, including prebronchodilatory spirometry, and gave blood for biochemical analyses. The blood was analyzed for high-sensitive C-reactive protein, fibrinogen, leukocytes, eosinophils, neutrophils, and immunoglobulin E (i.e., inflammatory biomarkers).
Dr. Landt and colleagues identified 8,181 patients (19% of the population) with COPD, 796 (10%) of whom had chronic cough. Of the 33,364 participants without COPD, 1,585 (5%) had chronic cough. For patients with COPD and chronic cough, median total Leicester Cough Questionnaire score was 17.7, corresponding to 5.9 for the physical domain, 5.6 for the psychological domain, and 6.3 for the social domain.
Among participants with COPD, those with chronic cough had higher rates of sputum production (60% versus 8%), wheezing (46% versus 14%), dyspnea (66% versus 38%), chest pain or tightness (9% versus 4%), nighttime dyspnea (8% versus 3%), episodes of acute bronchitis or pneumonias in the past 10 years (45% versus 25%), and general practitioner visits in the past 12 months (53% versus 37%). In addition, these participants had lower FEV1% of predicted (81% versus 89%), lower ratio of FEV1 to FVC (0.64 versus 0.66), and higher levels of high-sensitive C-reactive protein, fibrinogen, leukocytes, neutrophils, eosinophils, and immunoglobulin E in blood.
“To our knowledge, this is the first study reporting Leicester Cough Questionnaire score for randomly selected individuals with COPD from a general population setting,” wrote Dr. Landt and colleagues. The study’s strengths include its randomly chosen population-based sample and investigator blinding to disease status and clinical outcome, they added. Some patients with the most severe types of COPD and chronic cough may not have attended the physical examination and participated in the study, however, and this factor could have biased the results. Furthermore, nearly the entire sample was white, so the results may not be generalizable to other ethnicities. “That said, we are not aware of results to suggest that our findings should not be relevant to individuals of all races,” wrote the investigators.
The study was funded by the private Lundbeck Foundation, as well as by the Danish Lung Association and the Danish Cancer Society. Several authors reported receiving grants and fees from AstraZeneca, GlaxoSmithKline, and Novartis that were unrelated to the study.
SOURCE: Landt E et al. CHEST. 2020 Jan 24. doi: 10.1016/j.chest.2019.12.038.
, according to research published in CHEST.
The results indicate “that chronic cough in individuals with COPD is associated with a more severe disease phenotype, which could be helpful for stratifying management of COPD in the future,” wrote Eskild Landt, PhD, a research assistant at Zealand University Hospital in Køge, Denmark, and colleagues.
A study by published in the Journal of Allergy and Clinical Immunology: In Practice (2019;7[6]:1783-92.e8) indicated that in patients with asthma, chronic cough was associated with worse respiratory symptoms, more health care utilization, decreased lung function, and increased inflammatory markers in blood. Dr. Landt and colleagues hypothesized that patients with COPD and chronic cough had a similar pattern of disease severity.
To test their hypothesis, they identified individuals with COPD and chronic cough among 43,271 participants in the Copenhagen General Population Study, a population-based cohort study. The researchers defined COPD as a ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) of less than 0.70 in individuals without asthma. Consecutive individuals answered questions about chronic cough, which was defined as a cough lasting more than 8 weeks, and responded to the Leicester Cough Questionnaire. They also underwent a physical health examination, including prebronchodilatory spirometry, and gave blood for biochemical analyses. The blood was analyzed for high-sensitive C-reactive protein, fibrinogen, leukocytes, eosinophils, neutrophils, and immunoglobulin E (i.e., inflammatory biomarkers).
Dr. Landt and colleagues identified 8,181 patients (19% of the population) with COPD, 796 (10%) of whom had chronic cough. Of the 33,364 participants without COPD, 1,585 (5%) had chronic cough. For patients with COPD and chronic cough, median total Leicester Cough Questionnaire score was 17.7, corresponding to 5.9 for the physical domain, 5.6 for the psychological domain, and 6.3 for the social domain.
Among participants with COPD, those with chronic cough had higher rates of sputum production (60% versus 8%), wheezing (46% versus 14%), dyspnea (66% versus 38%), chest pain or tightness (9% versus 4%), nighttime dyspnea (8% versus 3%), episodes of acute bronchitis or pneumonias in the past 10 years (45% versus 25%), and general practitioner visits in the past 12 months (53% versus 37%). In addition, these participants had lower FEV1% of predicted (81% versus 89%), lower ratio of FEV1 to FVC (0.64 versus 0.66), and higher levels of high-sensitive C-reactive protein, fibrinogen, leukocytes, neutrophils, eosinophils, and immunoglobulin E in blood.
“To our knowledge, this is the first study reporting Leicester Cough Questionnaire score for randomly selected individuals with COPD from a general population setting,” wrote Dr. Landt and colleagues. The study’s strengths include its randomly chosen population-based sample and investigator blinding to disease status and clinical outcome, they added. Some patients with the most severe types of COPD and chronic cough may not have attended the physical examination and participated in the study, however, and this factor could have biased the results. Furthermore, nearly the entire sample was white, so the results may not be generalizable to other ethnicities. “That said, we are not aware of results to suggest that our findings should not be relevant to individuals of all races,” wrote the investigators.
The study was funded by the private Lundbeck Foundation, as well as by the Danish Lung Association and the Danish Cancer Society. Several authors reported receiving grants and fees from AstraZeneca, GlaxoSmithKline, and Novartis that were unrelated to the study.
SOURCE: Landt E et al. CHEST. 2020 Jan 24. doi: 10.1016/j.chest.2019.12.038.
FROM CHEST