Risk of Skin and Soft Tissue Infections among Children Found to be Staphylococcus aureus MRSA USA300 Carriers

Abstract

Introduction: The purpose of this study was to examine community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) carriage and infections and determine risk factors associated specifically with MRSA USA300.

Methods: We conducted a case control study in a pediatric emergency department. Nasal and axillary swabs were collected, and participants were interviewed for risk factors. The primary outcome was the proportion of S. aureus carriers among those presenting with and without a skin and soft tissue infection (SSTI). We further categorized S. aureus carriers into MRSA USA300 carriers or non-MRSA USA300 carriers.

Results: We found the MRSA USA300 carriage rate was higher in children less than two years of age, those with an SSTI, children with recent antibiotic use, and those with a family history of SSTI. MRSA USA300 carriers were also more likely to have lower income compared to non-MRSA USA300 carriers and no S. aureus carriers. Rates of Panton-Valentine leukocidin (PVL) genes were higher in MRSA carriage isolates with an SSTI, compared to MRSA carriage isolates of patients without an SSTI. There was an association between MRSA USA300 carriage and presence of PVL in those diagnosed with an abscess.

Conclusion: Children younger than two years were at highest risk for MRSA USA300 carriage. Lower income, recent antibiotic use, and previous or family history of SSTI were risk factors for MRSA USA300 carriage. There is a high association between MRSA USA300 nasal/axillary carriage and presence of PVL in those with abscesses.

Figure 1

Staphylococcus aureus carriage enrollment flow diagram. ^aDefinition for ‘No carriage’: No detection of S. aureus from SSTI wound culture or no detection of S. aureus from cultures obtained from nasal or axillary swabs. SSTI, skin and soft tissue infection; MRSA, methicillin resistant Staphylococcus aureus.

Figure 2

S. aureus carriage strains and body locations of skin and soft tissue infections. SSTI, skin and soft tissue infection; MRSA, methicillin resistant Staphylococcus aureus.

Figure 3

Distribution of nasal and axillary S. aureus carriage types between SSTI and no-SSTI groups. Note: No S. aureus carriage was detected in 668 swabs taken from either nasal, axillary areas: 96/668 were from SSTI group and 572/668 were from No SSTI group. SSTI, skin and soft tissue infection; MRSA, methicillin resistant Staphylococcus aureus.