In Vitro Antifungal-Antibacterial Combinations are Effective against MRSA in Candida Albicans-Staphylococcus Aureus Polymicrobial Biofilms

A significant proportion of human infections involve biofilms, which are more resistant to antimicrobial agents than their planktonic counterparts. It is well established that C. albicans readily forms polymicrobial biofilms with S. aureus. We hypothesized that the addition of an antifungal to an antibacterial, or combination therapy would be more effective in reducing the microbial load, most notably in polymicrobial biofilms, and possibly impact overall management of infection. In vitro results demonstrate that clinical strains of both methicillin-susceptible and methicillin-resistant S. aureus are less susceptible to vancomycin in polymicrobial biofilms with C. albicans when compared to S. aureus monomicrobial biofilms. Treatment of biofilms with either amphotericin B or caspofungin in combination with vancomycin resulted in greater inhibition and even elimination of methicillin-susceptible and methicillin-resistant S. aureus in C. albicans polymicrobial biofilms. The results of this study indicate that combination therapy should be a consideration in the management of polymicrobial biofilms, specifically C. albicans-S. aureus biofilm infections.