Staphylococcus aureus whole genome sequencing

Biocides, such as chlorhexidine, are widely used in the decolonisation of Staphylococcus aureus to prevent skin and soft tissue infections. However, tolerance to biocide remains unelucidated, partly due to the lack of a standardised susceptibility testing method and well-defined "resistance" mechanisms. Here, we use site-directed mutagenesis to investigate qacA-mediated biocide tolerance in a sequence type 45 methicillin-resistant S. aureus. Our findings provide experimental evidence supporting the role of qacA in conferring tolerance to quaternary ammonium compounds and co-selecting for broader antibiotic resistance in the presence of chlorhexidine.