Original Article
Molecular Epidemiology of Staphylococcus aureus in Households of Children with Community-Associated S aureus Skin and Soft Tissue Infections

https://doi.org/10.1016/j.jpeds.2013.08.072Get rights and content

Objectives

Although colonization traditionally is considered a risk factor for Staphylococcus aureus infection, the relationship between contemporary S aureus colonization and infection is not well characterized. We aimed to relate the presence of colonizing and disease-causing strains of S aureus within individuals and households.

Study design

In a prospective study of 163 pediatric outpatients (cases) with community-associated S aureus skin and soft tissue infections in St Louis, infection isolates were obtained from cases and colonization cultures were obtained from cases and their household contacts (n = 562). Molecular typing by repetitive sequence-based polymerase chain reaction was used to compare infecting and colonizing isolates within each case. The infecting strain from each case was compared with S aureus strains colonizing household contacts. The colonization status of cases was followed for 12 months.

Results

A total of 27 distinct strain types were identified among the 1299 S aureus isolates evaluated. Between 1 and 6 distinct strain types were detected per household. A total of 110 cases (67%) were colonized at 1 or more body sites with the infecting strain. Of the 53 cases with an infecting strain that did not match a colonizing strain, 15 (28%) had 1 or more household contacts with a colonizing strain that matched the infecting strain. Intrafamilial strain-relatedness was observed in 105 families (64%).

Conclusion

One-third of cases were colonized with a different strain type than the strain causing the skin and soft tissue infection. Fewer than one-third of cases with discordant infecting and colonizing isolates could be linked to the strain from another household contact, suggesting acquisition from sources outside the household.

Section snippets

Methods

This study was approved by Washington University's Human Research Protection Office. Informed consent was obtained from index cases and their household contacts at study enrollment. Samples for the present study were obtained from a decolonization trial recently performed by our group that enrolled pediatric patients with CA SSTIs.15 This trial included patients (“index cases”) aged 6 months to 20 years who received care at St Louis Children's Hospital emergency department and ambulatory wound

Index Patient and Household Contact Characteristics

The 163 cases had a total of 562 household contacts enrolled in the study; the median household size was 4 persons (range, 2-12). The median age of the cases was 2.8 years (range, 0.5-20 years). Seventy index cases (44%) experienced an SSTI in the year before study enrollment (Table I). The median age of the 562 household contacts was 22.0 years (range, 0.1-88 years). Of the 562 household contacts, 112 (21%) reported an SSTI in the year before study enrollment (Table I).

Baseline Colonization and SSTIs

Of 163 index cases, 104

Discussion

S aureus colonization is a documented risk factor for subsequent infection.3, 6 In the present study, 67% of our pediatric patients were colonized at baseline with at least 1 strain that matched the infecting strain. The infecting strain from 55% of these index cases was concordant with the colonizing strain from at least 1 household contact, suggesting possible unique characteristics regarding virulence and the potential for transmission of certain strain types. A striking 33% of cases had

References (26)

  • S.A. Fritz et al.

    Skin infection in children colonized with community-associated methicillin-resistant Staphylococcus aureus

    J Infect

    (2009)
  • P.L. Ho et al.

    Molecular epidemiology and household transmission of community-associated methicillin-resistant Staphylococcus aureus in Hong Kong

    Diagn Microbiol Infect Dis

    (2007)
  • R.S. Daum

    Clinical practice: skin and soft-tissue infections caused by methicillin-resistant Staphylococcus aureus

    N Engl J Med

    (2007)
  • C. Liu et al.

    Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children: executive summary

    Clin Infect Dis

    (2011)
  • S.L. Kaplan et al.

    Three-year surveillance of community-acquired Staphylococcus aureus infections in children

    Clin Infect Dis

    (2005)
  • G. Lina et al.

    Involvement of Panton-Valentine leukocidin–producing Staphylococcus aureus in primary skin infections and pneumonia

    Clin Infect Dis

    (1999)
  • M.W. Ellis et al.

    Natural history of community-acquired methicillin-resistant Staphylococcus aureus colonization and infection in soldiers

    Clin Infect Dis

    (2004)
  • C. von Eiff et al.

    Nasal carriage as a source of Staphylococcus aureus bacteremia

    N Engl J Med

    (2001)
  • A.E. Chen et al.

    Discordance between Staphylococcus aureus nasal colonization and skin infections in children

    Pediatr Infect Dis J

    (2009)
  • T.F. Jones et al.

    Family outbreaks of invasive community-associated methicillin-resistant Staphylococcus aureus infection

    Clin Infect Dis

    (2006)
  • Y.C. Huang et al.

    Nasal carriage of methicillin-resistant Staphylococcus aureus in household contacts of children with community-acquired diseases in Taiwan

    Pediatr Infect Dis J

    (2007)
  • X.W. Huijsdens et al.

    Multiple cases of familial transmission of community-acquired methicillin-resistant Staphylococcus aureus

    J Clin Microbiol

    (2006)
  • P.J. Johansson et al.

    High prevalence of MRSA in household contacts

    Scand J Infect Dis

    (2007)
  • Cited by (0)

    Supported by the Infectious Diseases Society of America/National Foundation for Infectious Diseases Pfizer Fellowship in Clinical Disease (to S.F.), the National Institutes of Health (UL1-RR024992, KL2RR024994, and K23-AI091690 to S.F.), the Agency for Healthcare Research and Quality (R01-HS021736 to S.F.), and the Children's Discovery Institute of Washington University and St. Louis Children's Hospital (to S.F.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Agency for Healthcare Research and Quality. The authors declare no conflicts of interest.

    Present affiliation: Southern Illinois University, Springfield, IL.

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