Characterization of SCCmec type IV methicillin-resistant Staphylococcus aureus clones increased in Japanese hospitals

Abstract

Recently, the prevalence of staphylococcal cassette chromosome <i>mec</i> (SCC<i>mec</i>) type IV isolates, which are the major community-acquired methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), have increased in Japanese hospitals. The aim of this study was to elucidate the detailed molecular epidemiological features of the SCC<i>mec</i> type IV clones in Japanese hospitals. When 2589 MRSA isolated from four hospitals in Tokyo, Japan between 2010 and 2014 were analysed, the proportion of SCC<i>mec</i> type IV overtook that of type II, which was the major type of hospital-acquired MRSA in 2014. Multilocus sequence typing showed that CC1 was the most predominant clone in the SCC<i>mec</i> type IV isolates. The clinical departments that the patients belonged to, pulsed-field gel electrophoresis analysis and antimicrobial susceptibility profiles suggested that the origin of the CC1-SCC<i>mec</i> type IV (CC1-IV) clone was a community setting. Our data show that the CC1-IV clone is becoming a predominant MRSA clone in Japanese hospitals.