Understanding the genomic and phenotypic evolution of methicillin-resistant Staphylococcus aureus sequence type 239 in Australia

A small number of clones are responsible for the majority of hospital-associated methicillin-resistant Staphylococcus aureus (MRSA) infections globally. One such clone, multi-locus sequence type 239 (ST239), has persisted in the healthcare setting for decades, but the basis for its success remains unknown. This study explored the evolution of ST239 MRSA in Australia using a collection of 123 geographically and temporally dispersed ST239 isolates. Phylogenetic reconstruction identified a previously unrecognised transmission event and functional analysis revealed that Australian ST239 MRSA have evolved enhanced antimicrobial resistance and attenuated virulence.