Evolving EMRSA-15 epidemic in Singapore hospitals

The aim of this study was to determine the extent of EMRSA-15 spread in hospitals in Singapore. Molecular analysis of 197 non-duplicate meticillin-resistant Staphylococcus aureus (MRSA) isolates collected from five acute care public hospitals in Singapore in May 2005 revealed that 66 (33.5%) were EMRSA-15 while 121 (61.4%) belonged to the endemic multidrug-resistant ST239 clone. Median and mode vancomycin MIC; for both major clones of health-care-associated MRSA were relatively high at 2.0 mu g ml(-1). Subsequent laboratory surveillance data collected from the first half of 2006 confirmed increasing numbers of the EMRSA-15 clone - ranging from 25.0 to 66.1% of all MRSA isolated in local hospitals-replacing the ST239 clone island-wide.