Role of Staphylococcus aureus global regulators sae and σB in virulence gene expression during device-related infection

The ability of Staphylococcus aureus to adapt to different environments is due to a regulatory network comprising several loci. Here we present a detailed study of the interaction between the two global regulators sae and sigma(B) of S. aureus and their influence on virulence gene expression in vitro, as well as during device-related infection. The expression of sae, asp23, hla, ctfA, coa, and fnbA was determined in strain Newman and its isogenic saeS/R and sigB mutants by Northern analysis and LightCycler reverse transcription-PCR. There was no indication of direct cross talk between the two regulators. sae had a dominant effect on target gene expression during device-related infection. sigma(B) seemed to be less active throughout the infection than under induced conditions in vitro.