Analysis of Interactions between Candida Albicans and Staphylococcus Aaureus in Mixed Species Biofilms

Analysis of Interactions between Candida Albicans and Staphylococcus Aaureus in 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. To date, most biofilm studies have focused on pure biofilms consisting of a single species rather than more natural biofilms that contain multiple species of bacteria and fungi. 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. Initial studies focused on whether each organism affects the attachment and growth of the other in the context of a biofilm. C. albicans attachment was shown to be enhanced by the presence of S. aureus when both are added at the same time to a plastic dish. Conversely, C. albicans attached less efficiently to the plastic surface if S. aureus was allowed to form a biofilm prior to adding the C. albicans. Furthermore, examination of organism growth within the biofilm revealed that the presence of S. aureus adversely affects the growth rate of C. albicans. These data suggest that the two organisms are interacting with one another within the biofilm. Scanning electron microscopy of the mixed biofilm appeared to confirm this hypothesis by showing the two organisms physically touching one another. Further studies will address whether the organisms affect one another’s ability to resist physical and chemical insults.