Possible role of sarA in dehydroepiandrosterone-mediated increase in Staphylococcus aureus resistance to vancomycin.

Background: Dehydroepiandrosterone (DHEA), a steroid present throughout life, can induce an increase in resistance to vancomycin in methicillin-sensitive and methicillin-resistant clinical isolates of Staphylococcus aureus.

Methods: The in vitro effect of DHEA on vancomycin killing of S. aureus with mutations in sarA and/or agr was determined by standard microtiter protocols and time to kill determinations.

Results: Of the isolates tested, the strain with a deletion in sarAderived from a DHEA- responsive parent was not protected from vancomycin killing by DHEA. However, DHEA significantly (p < 0.01) slowed the rate of vancomycin killing of sarA-.

Conclusion: These data indicate that sarA may play a role in DHEA-mediated protection from vancomycin killing of S. aureus.