Changes in molecular epidemiology of community-associated and health care-associated methicillin-resistant Staphylococcus aureus in Korean children.

Widespread emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has changed the epidemiology of S. aureus infections. We examined the molecular types and antibiotic susceptibility of CA-MRSA and health care-associated MRSA (HA-MRSA) among Korean children. MRSA isolates were obtained from patients admitted to university-affiliated tertiary hospitals in Korea, between 2006 and 2010. Molecular studies including multilocus sequence typing, SCCmec typing, and polymerase chain reaction amplification of PVL genes and antibiotic susceptibility tests were performed. SCCmec type IV was most frequently found for both CA-MRSA (80.0%) and HA-MRSA (56.4%). ST72-MRSA-SCCmec type IV and its single-locus variants were the most prevalent MRSA clones in the Korean pediatric population, both in community and in health care settings. The PVL genes were detected in 10% (4/40) of CA-MRSA isolates. Most of the clinical MRSA isolates showed vancomycin MIC ≥1.0 μg/mL. In conclusion, the molecular characteristics of HA-MRSA have been changing and CA-MRSA genotype overtook HA-MRSA genotype in health care settings.