Carriage of an ACME II variant may have contributed to methicillin-resistant Staphylococcus aureus sequence type 239-like strain replacement in Liverpool Hospital, Sydney, Australia.

Approximately 39% of methicillin-resistant Staphylococcus aureus (MRSA) sequence type 239 (ST239)-like bloodstream isolates from Liverpool Hospital (obtained between 1997 and 2008) carry an arginine catabolic mobile element (ACME). Whole-genome sequencing revealed that an ACME II variant is located between orfX and SCCmec III, and based on pulsed-field gel electrophoresis patterns and temporal relationships of all ST239-like isolates (n = 360), ACME carriage may have contributed to subpulsotype strain replacement.