High rates of MRSA colonization seen among children with S. aureus

Fritz SA. Arch Pediatr Adolesc Med. 2012;166(6):551-557.

  • June 14, 2012

Contacts of children who have been treated for skin infections associated with Staphylococcus aureus are likely to be colonized methicillin-resistant S. aureus themselves, according to a recently published study.

Stephanie A. Fritz, MD, and colleagues from the department of pediatrics at the Washington University School of Medicine in St. Louis performed a cross-sectional study of 183 children who were treated for S. aureus skin and soft tissue infections (SSTI) to examine the prevalence of S. aureus colonization among household contacts. The researchers also looked at household contact risk factors for colonization and considered anatomical colonization sites in both children and household contacts.

Of the children with S. aureus infection, 112 were colonized with MRSA; 54 had methicillin-sensitive S. aureus (MSSA); and 17 children were colonized with both.

Fritz and colleagues reported that of 609 household contacts, 323 were colonized with S. aureus; 115 were colonized with MRSA; 195 with MSSA; and 13 with both.

The researchers noted that parents were more likely to be colonized with MRSA than others living in the household. Household contacts closest to the age of the infected child also seemed more at risk for MRSA colonization, perhaps because these family members “may share a bed or a bath with the index patient or share toys or personal hygiene items,” the researchers wrote, adding that MRSA was more commonly found in the inguinal folds than MSSA, which was more likely found in the nares.

“Failure to identify all colonized household members may facilitate persistent colonization or recurrent infections,” Fritz and colleagues wrote. “In addition, household environmental surfaces and shared objects represent potential reservoirs for S. aureus transmission. However, there are no data to indicate whether routine household sampling or decolonization would be practical or cost-effective. Longitudinal studies are needed to illuminate S. aureus transmission dynamics between household members and their home environment.”

Disclosure: Dr. Fritz reports no relevant financial disclosures.

Perspective
C. Buddy Creech, MD, MPH

C. Buddy Creech

  • I’m not sure that Robinson Crusoe’s declaration to “share and share alike” should apply to microorganisms, but this work by Stephanie Fritz and colleagues in St. Louis demonstrates that it is indeed the case with Staphylococcus aureus. As clinicians, we are often faced with questions about how to treat family members of children with infectious diseases. For some, such as varicella or meningococcus, the epidemiology is well understood, and recommendations for protecting at-risk family members are fairly clear. For others, such as S. aureus, we simply do not yet know the most appropriate way to either: 1) interrupt the spread of the organism to at-risk contacts; or 2) avoid the development of clinical disease.

    Dr. Fritz has helped us in our understanding considerably, demonstrating that more than half of household contacts of children with SSTI share S. aureus carriage. While molecular data are not available, one would presume that in many of these situations, the strain types within a family are concordant, suggesting that a family, as a whole, might harbor a distinct clone of S. aureus. Further, we find that nasal cultures alone may be insensitive in identifying all carriers of contemporary S. aureus strains, given the high frequency of inguinal carriage alone (about 20%).

    The implications of these findings are twofold. First, screening methods that sample only the nares will identify many, but not all carriers of S. aureus. Second, since staphylococcal colonization appears to be a “game the whole family can play,” strategies for decolonization of index cases should take into consideration the likely colonization of family members, as Dr. Fritz’s group has recently shown.

    • C. Buddy Creech, MD, MPH
    • Infectious Diseases in Children Editorial Board
  • Disclosures: Dr. Creech reports no relevant financial disclosures.

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