Improved Eradication Efficacy of a Combination of Newly Identified Antimicrobial Agents in C. albicans and S. aureus Mixed-species Biofilm

Candida albicans and Staphylococcus aureus are common human pathogens, frequently isolated independently or co-isolated from bloodstream infections, and able to form dense polymicrobial biofilms on various medical devices resulting in strong resistance to conventionally used antimicrobials. New and innovative approaches are therefore needed to ensure the successful management of biofilm related infections. In this study, a chalcone-based derivative and a polycyclic anthracene-maleimide adduct, previously ascertained by us as inhibitors of C. albicans and S. aureus growths, respectively, were reconsidered in a new perspective by evaluating the efficacy of a combined treatment against a polymicrobial biofilm. Both quantitative and qualitative analyses were carried out to delve into their inhibitory potential on the polymicrobial population. Our results indicate that these newly identified antimicrobials are effective in reducing the biomass of the mixed C. albicans-S. aureus biofilm and the viability of fungal-bacterial cells within the polymicrobial community; in addition, confocal laser scanning microscopy demonstrates that the combined treatment thoroughly modifies the architecture of the dual-species biofilm.