Procalcitonin useful in controlling antibiotic resistance

Despite some controversy over its efficacy, the biomarker procalcitonin does have a legitimate role to play in helping determine the duration of antibiotic therapy in community-acquired infections, according to a presenter at the annual meeting of the American College of Chest Physicians.

Procalcitonin is a biomarker of inflammation that, like C-reactive protein, is seen at higher levels in patients with bacterial infections. How statistically significant a difference it will make in curbing antibiotic use in a hospital and helping to stratify risk "depends on what your baseline [of antibiotic use] is," said Dr. Richard Wunderink, FCCP, of Northwestern University, Chicago.

Dr. Wunderink cited two meta-analyses, including a Cochrane Database systematic review of patient-level data, that showed "highly statistically significant differences" in the duration of antibiotic therapy when procalcitonin was measured. In the study, 898 out of 999 patients with community-acquired pneumonia were given antibiotics and had their procalcitonin levels measured; the control group, numbering 1,028, was also given antibiotics but did not have procalcitonin levels measured (Cochrane Database Syst. Rev. 2012 Sept. 12;9:CD007498 [doi: 10.1002/14651858.CD007498.pub2]).

The group measured for elevated procalcitonin as a way of determining the course of antibiotic therapy had an average exposure to antibiotics of 6 days, compared with an average exposure of 10 days in the control group.

"It does shorten the course of therapy," said Dr. Wunderink. However, he added, there has been an effort over the past decade in the United States to reduce overall antibiotic therapy as a way to combat antibacterial resistance, so the difference is less than it might be in European countries.

Also important to consider, said Dr. Wunderink, is the ongoing inflammatory response in some patients. "There is a point at which the cytokines response starts to drive the procalcitonin more than the bacteria do ... so at some point, it switches from being a marker of uncontrolled bacterial infection to a marker of uncontrolled inflammation," Dr. Wunderink said.

Another issue, he said, is that physicians "need to be comfortable withholding antibiotics in patients with community-acquired pneumonia," since some patients will not have notably elevated procalcitonin levels, regardless of infection. "It may be that procalcitonin can tell you enough about etiology that you can treat for atypicals, but it’s still to be proven," said Dr. Wunderink.

When there is diagnostic uncertainty, as in a patient who has underlying heart failure and symptoms that may or may not be pneumonia, Dr. Wunderink said that short-course antibiotic therapy, such as 5-7 days, is appropriate.

"But I am not sure that procalcitonin actually decreases that duration of therapy," he said. "It may support the idea of narrower-spectrum atypical antibiotic therapy, but the greatest benefit is in discontinuing the therapy in patients with diagnostic uncertainty."

Dr. Wunderink disclosed that he has received investigator grants from bioMérieux.

[email protected]

Despite some controversy over its efficacy, the biomarker procalcitonin does have a legitimate role to play in helping determine the duration of antibiotic therapy in community-acquired infections, according to a presenter at the annual meeting of the American College of Chest Physicians.

Procalcitonin is a biomarker of inflammation that, like C-reactive protein, is seen at higher levels in patients with bacterial infections. How statistically significant a difference it will make in curbing antibiotic use in a hospital and helping to stratify risk "depends on what your baseline [of antibiotic use] is," said Dr. Richard Wunderink, FCCP, of Northwestern University, Chicago.

Dr. Wunderink cited two meta-analyses, including a Cochrane Database systematic review of patient-level data, that showed "highly statistically significant differences" in the duration of antibiotic therapy when procalcitonin was measured. In the study, 898 out of 999 patients with community-acquired pneumonia were given antibiotics and had their procalcitonin levels measured; the control group, numbering 1,028, was also given antibiotics but did not have procalcitonin levels measured (Cochrane Database Syst. Rev. 2012 Sept. 12;9:CD007498 [doi: 10.1002/14651858.CD007498.pub2]).

The group measured for elevated procalcitonin as a way of determining the course of antibiotic therapy had an average exposure to antibiotics of 6 days, compared with an average exposure of 10 days in the control group.

"It does shorten the course of therapy," said Dr. Wunderink. However, he added, there has been an effort over the past decade in the United States to reduce overall antibiotic therapy as a way to combat antibacterial resistance, so the difference is less than it might be in European countries.

Also important to consider, said Dr. Wunderink, is the ongoing inflammatory response in some patients. "There is a point at which the cytokines response starts to drive the procalcitonin more than the bacteria do ... so at some point, it switches from being a marker of uncontrolled bacterial infection to a marker of uncontrolled inflammation," Dr. Wunderink said.

Another issue, he said, is that physicians "need to be comfortable withholding antibiotics in patients with community-acquired pneumonia," since some patients will not have notably elevated procalcitonin levels, regardless of infection. "It may be that procalcitonin can tell you enough about etiology that you can treat for atypicals, but it’s still to be proven," said Dr. Wunderink.

When there is diagnostic uncertainty, as in a patient who has underlying heart failure and symptoms that may or may not be pneumonia, Dr. Wunderink said that short-course antibiotic therapy, such as 5-7 days, is appropriate.

"But I am not sure that procalcitonin actually decreases that duration of therapy," he said. "It may support the idea of narrower-spectrum atypical antibiotic therapy, but the greatest benefit is in discontinuing the therapy in patients with diagnostic uncertainty."

Dr. Wunderink disclosed that he has received investigator grants from bioMérieux.

[email protected]

Despite some controversy over its efficacy, the biomarker procalcitonin does have a legitimate role to play in helping determine the duration of antibiotic therapy in community-acquired infections, according to a presenter at the annual meeting of the American College of Chest Physicians.

Procalcitonin is a biomarker of inflammation that, like C-reactive protein, is seen at higher levels in patients with bacterial infections. How statistically significant a difference it will make in curbing antibiotic use in a hospital and helping to stratify risk "depends on what your baseline [of antibiotic use] is," said Dr. Richard Wunderink, FCCP, of Northwestern University, Chicago.

Dr. Wunderink cited two meta-analyses, including a Cochrane Database systematic review of patient-level data, that showed "highly statistically significant differences" in the duration of antibiotic therapy when procalcitonin was measured. In the study, 898 out of 999 patients with community-acquired pneumonia were given antibiotics and had their procalcitonin levels measured; the control group, numbering 1,028, was also given antibiotics but did not have procalcitonin levels measured (Cochrane Database Syst. Rev. 2012 Sept. 12;9:CD007498 [doi: 10.1002/14651858.CD007498.pub2]).

The group measured for elevated procalcitonin as a way of determining the course of antibiotic therapy had an average exposure to antibiotics of 6 days, compared with an average exposure of 10 days in the control group.

"It does shorten the course of therapy," said Dr. Wunderink. However, he added, there has been an effort over the past decade in the United States to reduce overall antibiotic therapy as a way to combat antibacterial resistance, so the difference is less than it might be in European countries.

Also important to consider, said Dr. Wunderink, is the ongoing inflammatory response in some patients. "There is a point at which the cytokines response starts to drive the procalcitonin more than the bacteria do ... so at some point, it switches from being a marker of uncontrolled bacterial infection to a marker of uncontrolled inflammation," Dr. Wunderink said.

Another issue, he said, is that physicians "need to be comfortable withholding antibiotics in patients with community-acquired pneumonia," since some patients will not have notably elevated procalcitonin levels, regardless of infection. "It may be that procalcitonin can tell you enough about etiology that you can treat for atypicals, but it’s still to be proven," said Dr. Wunderink.

When there is diagnostic uncertainty, as in a patient who has underlying heart failure and symptoms that may or may not be pneumonia, Dr. Wunderink said that short-course antibiotic therapy, such as 5-7 days, is appropriate.

"But I am not sure that procalcitonin actually decreases that duration of therapy," he said. "It may support the idea of narrower-spectrum atypical antibiotic therapy, but the greatest benefit is in discontinuing the therapy in patients with diagnostic uncertainty."

Dr. Wunderink disclosed that he has received investigator grants from bioMérieux.

[email protected]