Molecular characteristics of methicillin-resistant Staphylococcus aureus isolated from skin and soft tissue infections collected in the Japanese nationwide surveillance.

Skin and soft tissue infections (SSTI) are a common infection among both outpatients and inpatients. The most frequently isolated bacterium in SSTI was Staphylococcus aureus, a quarter of which was methicillin-resistant S. aureus (MRSA). In this study, to investigate molecular epidemiology of the 141 MRSA strains collected in the Japanese nationwide surveillance, we performed multiplex real-time polymerase chain reaction to detect staphylococcal cassette chromosome mec (SCCmec) type and virulence genes. The percentage of SCCmec types I, II, III and IV was 1.4%, 52.5%, 5.7% and 40.4%, respectively. According to the SCCmec type, we classified the strains into health-care-associated (HA)-MRSA (n = 84) and community-associated (CA)-MRSA (n = 57). Among the virulence genes, the percentage of enterotoxin C gene-positive strains was significantly higher in CA-MRSA than in HA-MRSA. No significant differences were detected between the two groups in terms of antibiotic susceptibility and patients' background information, classification of SSTI or symptoms of SSTI.