Phase variation (PV) is a well-known phenomenon of high-frequency reversible gene-expression
switching. PV arises from genetic and epigenetic mechanisms and confers a range of
benefits to bacteria, constituting both an innate immune strategy to infection from
bacteriophages as well as an adaptation strategy within an infected host. PV has been
well-characterized in numerous bacterial species; however, there is limited direct
evidence of PV in the human opportunistic pathogen Staphylococcus aureus. This review
provides an overview of the mechanisms that generate PV and focuses on earlier and
recent findings of PV in S. aureus, with a brief look at the future of the field.