Propionibacterium acnes biofilm – A sanctuary for Staphylococcus aureus?

•Propionibacterium acnes enhances virulence factors of Staphylococcus aureus under anaerobic conditions.•S. aureus grows well under anaerobic conditions.•The inside of a human body is more consistent with an anaerobic environment.•Aerobic organisms may behave differently when grown anaerobically.

The purpose of this study was to measure the effect of combined culture of Propionibacterium acnes and Staphylococcus aureus on biofilm formation under different oxygen concentrations. We measured planktonic growth and biofilm formation of P. acnes and S. aureus alone and together under aerobic and anaerobic conditions. Both P. acnes and S. aureus grew under anaerobic conditions. When grown under anaerobic conditions, P. acnes with or without S. aureus formed a denser biomass biofilm than did S. aureus alone. Viable S. aureus was recovered from a16-day old combined P. acnes and S. aureus biofilm, but not a monomicrobial S. aureus biofilm.