Phages of Staphylococcus aureus and their impact on host evolution

•We summarize recent advances regarding biology of Staphylococcus aureus phages.•Conserved phage modules can be identified and functions predicted.•Phage-encoded virulence genes are linked to the spreading of bacterial clones.•Phages are important for diversification of the bacterial host.

Most of the dissimilarity between Staphylococcus aureus strains is due to the presence of mobile genetic elements such as bacteriophages or pathogenicity islands. These elements provide the bacteria with additional genes that enable them to establish a new lifestyle that is often accompanied by a shift to increased pathogenicity or a jump to a new host. S. aureus phages may carry genes coding for diverse virulence factors such as Panton-Valentine leukocidin, staphylokinase, enterotoxins, chemotaxis-inhibitory proteins, or exfoliative toxins. Phages also mediate the transfer of pathogenicity islands in a highly coordinated manner and are the primary vehicle for the horizontal transfer of chromosomal and extra-chromosomal genes. Here, we summarise recent advances regarding phage classification, genome organisation and function of S. aureus phages with a particular emphasis on their role in the evolution of the bacterial host.