Selection for qacA carriage in CC22, but not CC30, methicillin-resistant Staphylococcus aureus bloodstream infection isolates during a successful institutional infection control programme

Conclusions: A successful infection control programme was associated with the selection of qacA linked with a higher chlorhexidine MIC in one dominant endemic MRSA clone (CC22), but not another (CC30). The slower reduction in the CC22 MRSA BSI rate suggests that carriage of qacA confers a selective advantage, with implications for the sustainability of decolonization practice.