Dissemination of Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus USA300 clone in multiple hospitals in Tokyo, Japan.

OBJECTIVES: Panton-Valentine leukocidin (PVL) gene (lukS/F-PV)-positive community-acquired methicillin-resistant Staphylococcus aureus (MRSA), particularly the USA300 clone, is a health concern worldwide. Recently, community-acquired MRSA clones have been found to spread and persist in hospital settings. We aimed to investigate the prevalence and molecular epidemiologic features of lukS/F-PV-positive MRSA in Japanese hospitals.

METHODS: A total of 3433 MRSA isolated from nine hospitals in 2011-2015 were assessed. Molecular epidemiologic analysis performed by staphylococcal cassette chromosome mec typing, PVL typing, arginine catabolic mobile element typing, detection of virulence determinants, multilocus sequence typing, pulsed-field gel electrophoresis and antimicrobial susceptibility testing.

RESULTS: The detection rate of lukS/F-PV was increased annually from 0.6% (5/817) in 2011 to 3.1% (17/544) in 2015. Molecular epidemiologic analysis for 64 lukS/F-PV-positive MRSA isolates revealed that 42 isolates (65.6%) were the USA300 clone. Resistance rates of levofloxacin and gentamicin among lukS/F-PV-positive isolates increased annually as a result of increased prevalence of the multidrug-resistant USA300 clone.

CONCLUSIONS: This is the first report on dissemination of the USA300 clone and PVL-positive MRSA in multiple Japanese hospitals. Our data strongly suggest that the USA300 clone may become epidemic in Japanese hospitals.