CA-MRSA Less Likely In Atopic Children

PHILADELPHIA — Community-associated methicillin-resistant Staphylococcus aureus skin infections occur significantly less often among children with atopic dermatitis than among other outpatients with skin and soft tissue infections, based on a retrospective study of 78 children.

Children with atopic dermatitis (AD) and Staphylococcus aureus skin infections had a relatively low incidence (14%) of methicillin resistance, much lower than the rate noted (45.5%) in other outpatient services during the same period, Dr. Catalina Matiz and her colleagues wrote in a poster presented at the annual meeting of the Society for Pediatric Dermatology.

Dr. Matiz, a postdoctoral fellow at Rady Children's Hospital in San Diego, and her coinvestigators conducted a retrospective chart review of 78 children with super-infected AD seen at the Rady pediatric and adolescent dermatology clinic between June 2007 and June 2008. The children had a positive skin culture for S. aureus.

They compared these data with all skin and soft tissue infection outpatient samples sent to the hospital's microbiology lab during the same period, and also with those sent during January 2000 through January 2001 (excluding samples from the dermatology clinic).

The CA-MRSA rate for samples from outpatient services from 2000-2001 was 4% (192 S. aureus-positive cultures). The outpatient services' rates increase from 2000-2001 to 2007-2008, highlight the sharp increase in CA-MRSA over the last several years, Dr. Matiz noted.

The rate of community-associated methicillin-sensitive S. aureus among patients with AD was 86%. In comparison, the CA-MSSA rate for other outpatient services during the same period was 55%. The CA-MSSA rate for outpatient services from 2000-2001 was 96%.

Interestingly, the investigators found that prior history of hospitalization, eczema severity, age, gender and prior antibiotic treatment had no impact on risk of methicillin resistance or sensitivity in these patients.

For the patients with AD, positive S. aureus cultures were most common among patients aged 1-4 years (26%), followed by those aged 5-9 years (24%), and those less than a year (23%).

The double diffusion test (D-test)—which is used to assess inducible resistance to clindamycin—was performed for 576 of the CA-MRSA samples from the hospital's lab in 2008. In all, 2% were positive for clindamycin-inducible resistance. However, none of the D-tests performed on cultures from patients with AD were positive. D-tests were performed for six of nine cultures that showed erythromycin resistance among patients with AD.

The findings are striking. “It's absolutely counterintuitive because if you think of patients with AD as being more at risk for infection, you would think that at the very least they would have the same rate as that occurring in the regular population,” said Dr. Sheila Fallon Friedlander, a study coauthor and a professor of pediatrics and medicine at the University of California, San Diego.

Based on conversations with colleagues, other pediatric dermatologists seem to be seeing similar patterns, said Dr. Friedlander. The researchers are not sure why these children have fewer CA-MRSA infections, though they have a couple of ideas.

It may be that “because these kids are colonized already so much of the time with regular S. aureus, that it may exert sort of a protective effect against CA-MRSA,” Dr. Friedlander said.

In addition, patients with AD tend to present more often with multiple lesions. “That may also play a role in this. It may be that our atopic patients are presenting with secondarily-infected lesions that are distinct from the abscesses and the folliculitis that we are seeing in the community,” she noted.

The findings “have informed the way that I prescribe medications for my patients,” she said. The results suggest that more standard antibiotic drugs with fewer side effects—like cephalosporins—can be used first, especially while waiting for culture results. This could not only reduce costs but also save patients from more serious side effects of antibiotics used for resistant pathogens.

In addition, it would help to reduce selection of more resistant bacteria. “It [could protect] our bigger gun drugs—reserving them for when you really need them,” said Dr. Friedlander, who added that it is important to factor in local demographics about CA-MRSA infection when deciding on a treatment.

Dr. Friedlander pointed out that while the findings are very interesting, this is a small study. “I think it's an interesting first step,” she said. Further prospective studies, looking at both CA-MRSA colonization and infection rates in children with AD, will be important to confirm these results.

In a separate study also presented at the meeting, Canadian researchers found a MRSA colonization rate of 0.5% among 200 pediatric patients with AD, and a S. aureus colonization rate of 61%.

The researchers collected a total of 400 swabs from the nares and open areas/folds of ADpatients (aged 1 month-18 years) with intact skin. Severity of AD was assessed using the an AD severity score, said Dr. Alexandra Balma-Mena, a resident at the Hospital for Sick Children in Toronto. A score of 0-12 was considered mild disease, a score of 13-18 was considered moderate, and a score of 19-25 was considered severe.

More of the patients were male (57%); the average age was 5 years. Most patients had mild disease (66%), followed by moderate (30%), and severe (4%).

Dr. Sheila Fallon Friedlander (left) and Dr. Catalina Matiz found that children with atopic dermatitis and S. aureus had a relatively lower incidence of methicillin resistance.

Source Courtesy Rady Children's Hospital in San Diego

PHILADELPHIA — Community-associated methicillin-resistant Staphylococcus aureus skin infections occur significantly less often among children with atopic dermatitis than among other outpatients with skin and soft tissue infections, based on a retrospective study of 78 children.

Children with atopic dermatitis (AD) and Staphylococcus aureus skin infections had a relatively low incidence (14%) of methicillin resistance, much lower than the rate noted (45.5%) in other outpatient services during the same period, Dr. Catalina Matiz and her colleagues wrote in a poster presented at the annual meeting of the Society for Pediatric Dermatology.

Dr. Matiz, a postdoctoral fellow at Rady Children's Hospital in San Diego, and her coinvestigators conducted a retrospective chart review of 78 children with super-infected AD seen at the Rady pediatric and adolescent dermatology clinic between June 2007 and June 2008. The children had a positive skin culture for S. aureus.

They compared these data with all skin and soft tissue infection outpatient samples sent to the hospital's microbiology lab during the same period, and also with those sent during January 2000 through January 2001 (excluding samples from the dermatology clinic).

The CA-MRSA rate for samples from outpatient services from 2000-2001 was 4% (192 S. aureus-positive cultures). The outpatient services' rates increase from 2000-2001 to 2007-2008, highlight the sharp increase in CA-MRSA over the last several years, Dr. Matiz noted.

The rate of community-associated methicillin-sensitive S. aureus among patients with AD was 86%. In comparison, the CA-MSSA rate for other outpatient services during the same period was 55%. The CA-MSSA rate for outpatient services from 2000-2001 was 96%.

Interestingly, the investigators found that prior history of hospitalization, eczema severity, age, gender and prior antibiotic treatment had no impact on risk of methicillin resistance or sensitivity in these patients.

For the patients with AD, positive S. aureus cultures were most common among patients aged 1-4 years (26%), followed by those aged 5-9 years (24%), and those less than a year (23%).

The double diffusion test (D-test)—which is used to assess inducible resistance to clindamycin—was performed for 576 of the CA-MRSA samples from the hospital's lab in 2008. In all, 2% were positive for clindamycin-inducible resistance. However, none of the D-tests performed on cultures from patients with AD were positive. D-tests were performed for six of nine cultures that showed erythromycin resistance among patients with AD.

The findings are striking. “It's absolutely counterintuitive because if you think of patients with AD as being more at risk for infection, you would think that at the very least they would have the same rate as that occurring in the regular population,” said Dr. Sheila Fallon Friedlander, a study coauthor and a professor of pediatrics and medicine at the University of California, San Diego.

Based on conversations with colleagues, other pediatric dermatologists seem to be seeing similar patterns, said Dr. Friedlander. The researchers are not sure why these children have fewer CA-MRSA infections, though they have a couple of ideas.

It may be that “because these kids are colonized already so much of the time with regular S. aureus, that it may exert sort of a protective effect against CA-MRSA,” Dr. Friedlander said.

In addition, patients with AD tend to present more often with multiple lesions. “That may also play a role in this. It may be that our atopic patients are presenting with secondarily-infected lesions that are distinct from the abscesses and the folliculitis that we are seeing in the community,” she noted.

The findings “have informed the way that I prescribe medications for my patients,” she said. The results suggest that more standard antibiotic drugs with fewer side effects—like cephalosporins—can be used first, especially while waiting for culture results. This could not only reduce costs but also save patients from more serious side effects of antibiotics used for resistant pathogens.

In addition, it would help to reduce selection of more resistant bacteria. “It [could protect] our bigger gun drugs—reserving them for when you really need them,” said Dr. Friedlander, who added that it is important to factor in local demographics about CA-MRSA infection when deciding on a treatment.

Dr. Friedlander pointed out that while the findings are very interesting, this is a small study. “I think it's an interesting first step,” she said. Further prospective studies, looking at both CA-MRSA colonization and infection rates in children with AD, will be important to confirm these results.

In a separate study also presented at the meeting, Canadian researchers found a MRSA colonization rate of 0.5% among 200 pediatric patients with AD, and a S. aureus colonization rate of 61%.

The researchers collected a total of 400 swabs from the nares and open areas/folds of ADpatients (aged 1 month-18 years) with intact skin. Severity of AD was assessed using the an AD severity score, said Dr. Alexandra Balma-Mena, a resident at the Hospital for Sick Children in Toronto. A score of 0-12 was considered mild disease, a score of 13-18 was considered moderate, and a score of 19-25 was considered severe.

More of the patients were male (57%); the average age was 5 years. Most patients had mild disease (66%), followed by moderate (30%), and severe (4%).

Dr. Sheila Fallon Friedlander (left) and Dr. Catalina Matiz found that children with atopic dermatitis and S. aureus had a relatively lower incidence of methicillin resistance.

Source Courtesy Rady Children's Hospital in San Diego

PHILADELPHIA — Community-associated methicillin-resistant Staphylococcus aureus skin infections occur significantly less often among children with atopic dermatitis than among other outpatients with skin and soft tissue infections, based on a retrospective study of 78 children.

Children with atopic dermatitis (AD) and Staphylococcus aureus skin infections had a relatively low incidence (14%) of methicillin resistance, much lower than the rate noted (45.5%) in other outpatient services during the same period, Dr. Catalina Matiz and her colleagues wrote in a poster presented at the annual meeting of the Society for Pediatric Dermatology.

Dr. Matiz, a postdoctoral fellow at Rady Children's Hospital in San Diego, and her coinvestigators conducted a retrospective chart review of 78 children with super-infected AD seen at the Rady pediatric and adolescent dermatology clinic between June 2007 and June 2008. The children had a positive skin culture for S. aureus.

They compared these data with all skin and soft tissue infection outpatient samples sent to the hospital's microbiology lab during the same period, and also with those sent during January 2000 through January 2001 (excluding samples from the dermatology clinic).

The CA-MRSA rate for samples from outpatient services from 2000-2001 was 4% (192 S. aureus-positive cultures). The outpatient services' rates increase from 2000-2001 to 2007-2008, highlight the sharp increase in CA-MRSA over the last several years, Dr. Matiz noted.

The rate of community-associated methicillin-sensitive S. aureus among patients with AD was 86%. In comparison, the CA-MSSA rate for other outpatient services during the same period was 55%. The CA-MSSA rate for outpatient services from 2000-2001 was 96%.

Interestingly, the investigators found that prior history of hospitalization, eczema severity, age, gender and prior antibiotic treatment had no impact on risk of methicillin resistance or sensitivity in these patients.

For the patients with AD, positive S. aureus cultures were most common among patients aged 1-4 years (26%), followed by those aged 5-9 years (24%), and those less than a year (23%).

The double diffusion test (D-test)—which is used to assess inducible resistance to clindamycin—was performed for 576 of the CA-MRSA samples from the hospital's lab in 2008. In all, 2% were positive for clindamycin-inducible resistance. However, none of the D-tests performed on cultures from patients with AD were positive. D-tests were performed for six of nine cultures that showed erythromycin resistance among patients with AD.

The findings are striking. “It's absolutely counterintuitive because if you think of patients with AD as being more at risk for infection, you would think that at the very least they would have the same rate as that occurring in the regular population,” said Dr. Sheila Fallon Friedlander, a study coauthor and a professor of pediatrics and medicine at the University of California, San Diego.

Based on conversations with colleagues, other pediatric dermatologists seem to be seeing similar patterns, said Dr. Friedlander. The researchers are not sure why these children have fewer CA-MRSA infections, though they have a couple of ideas.

It may be that “because these kids are colonized already so much of the time with regular S. aureus, that it may exert sort of a protective effect against CA-MRSA,” Dr. Friedlander said.

In addition, patients with AD tend to present more often with multiple lesions. “That may also play a role in this. It may be that our atopic patients are presenting with secondarily-infected lesions that are distinct from the abscesses and the folliculitis that we are seeing in the community,” she noted.

The findings “have informed the way that I prescribe medications for my patients,” she said. The results suggest that more standard antibiotic drugs with fewer side effects—like cephalosporins—can be used first, especially while waiting for culture results. This could not only reduce costs but also save patients from more serious side effects of antibiotics used for resistant pathogens.

In addition, it would help to reduce selection of more resistant bacteria. “It [could protect] our bigger gun drugs—reserving them for when you really need them,” said Dr. Friedlander, who added that it is important to factor in local demographics about CA-MRSA infection when deciding on a treatment.

Dr. Friedlander pointed out that while the findings are very interesting, this is a small study. “I think it's an interesting first step,” she said. Further prospective studies, looking at both CA-MRSA colonization and infection rates in children with AD, will be important to confirm these results.

In a separate study also presented at the meeting, Canadian researchers found a MRSA colonization rate of 0.5% among 200 pediatric patients with AD, and a S. aureus colonization rate of 61%.

The researchers collected a total of 400 swabs from the nares and open areas/folds of ADpatients (aged 1 month-18 years) with intact skin. Severity of AD was assessed using the an AD severity score, said Dr. Alexandra Balma-Mena, a resident at the Hospital for Sick Children in Toronto. A score of 0-12 was considered mild disease, a score of 13-18 was considered moderate, and a score of 19-25 was considered severe.

More of the patients were male (57%); the average age was 5 years. Most patients had mild disease (66%), followed by moderate (30%), and severe (4%).

Dr. Sheila Fallon Friedlander (left) and Dr. Catalina Matiz found that children with atopic dermatitis and S. aureus had a relatively lower incidence of methicillin resistance.

Source Courtesy Rady Children's Hospital in San Diego