Increased Vancomycin Resistance Exhibited By Staphylococcus Aureus Grown Together With Candida Albicans within Mixed Species Biofilms

Increased Vancomycin Resistance Exhibited By Staphylococcus Aureus Grown Together With Candida Albicans within Mixed Species Biofilms

Biofilms are multicellular communities of microorganisms that characteristically attach to some surface, produce and encase themselves within a thick polysaccharide matrix, and resist physical insults and treatment with anti-microbial drugs. The studies described here focus on characterizing the physical interactions between a bacterium (Staphylococcus aureus) and fungus (Candida albicans) in the context of a mixed biofilm. Both of these organisms are common human pathogens that cause a variety of human disease. Previous findings in our lab have suggested that C. albicans and S. aureus interact with one another and alter the other’s ability to attach and grow within a biofilm. Current studies are aimed at determining whether this interaction also affects their ability to resist physical insults or treatment with antibiotics. As a start to this, mixed biofilms and pure biofilms containing C. albicans were subjected to strong agitation and the amount of detachment from the surface was measured. The pure biofilms were shown to detach more readily than did mixed biofilms, suggesting that mixed biofilms are structurally more stable than pure biofilms. Similarly, pure C. albicans biofilms appear to naturally release very large cellular aggregates during the course of growth when compared to mixed biofilms. Furthermore, C. albicans appeared to confer S. aureus with increased resistance to the antibiotic vancomycin. In contrast, S. aureus did not exhibit increased resistance to a different antibiotic (rifampin) in similar conditions, suggesting that the increased vancomycin resistance may be due to some specific biochemical or genetic modification of S. aureus by C. albicans.