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In this study, we evaluated genetic differentiation between methicillin-resistant Staphylococcus aureus (MRSA) strains from Korea and Japan. Seventy-five MRSA strains, including 25 h VISA strains, were analyzed by molecular typing methods, including multilocus sequence typing (MLST), SCC mec typing, and spa typing. The most prevalent genotype of MRSA strains, in both Korea and Japan, was ST 5-MRSA-II with the DMGMK spa motif, characteristic of the New York/Japan MRSA clone. In spite of these common features in MRSA strains from Korea and Japan, we also observed some genotypic divergence in MRSA from the two countries. Several spa types might be differentiated from a prevalent prototype (TJMBMDMGMK) that is shared by the two countries, revealing a unique geographic distribution. SCC mec type II lacking pUB110, designated type IIA, was found more frequently in Korea than in Japan. The rate of gentamicin resistance was also dramatically different between the two countries: 87.2% (Korea) vs. 28.6% (Japan). These preliminary findings suggested that MRSA strains from Korea and Japan might have originated from a common ancestor, but then clearly differentiated according to locality. A further comprehensive study should be performed to document the hypotheses from this study.

Recent reports on some methicillin-resistant Staphylococcus aureus (MRSA) with reduced susceptibility to vancomycin have been a major concern in Korea because of the widespread use of vancomycin due to a high prevalence of MRSA in the country. We describe a 45-year-old man with long-standing pelvic abscess due to MRSA. In spite of vancomycin and teicoplanin treatment for a long period of time, the patient died from MRSA sepsis. The blood culture isolate of MRSA exhibited reduced susceptibility to vancomycin (MIC, 8 microg/ml). This is the first report of a vancomycin-intermediate S. aureus case from Korea.