Inhibition of Candida albicans and Staphylococcus epidermidis mixed biofilm formation in a catheter disk model system treated with EtOH–EDTA solution

Abstract Microbial colonization and the formation of biofilms on catheter surfaces pose a great risk for medical-related infections. We aimed (a) to evaluate polymicrobial biofilm formation of Candida albicans and Staphylococcus epidermidis and (b) to investigate the inhibition and effects of ethanol (EtOH) and EtOH–EDTA solutions on biofilms. Catheter disks were made and used as a substrate for biofilm formation. Varying concentrations of EtOH and EtOH–EDTA solutions were compared in deterring biofilm formation. The EtOH–EDTA solutions were further tested to remove mature and preformed biofilms. Compared to their monospecies counterparts, biofilm concentration significantly increases when C. albicans is co-cultured with S. epidermidis. Moreover, all treatments with EtOH–EDTA solution significantly lowered biofilm formation compared to EtOH alone (P ≤ 0.05). Lastly, biofilm was dramatically reduced when treated with 20%, 30%, 40%, and 50% EtOH–EDTA solutions (P ≤ 0.05). Our findings suggest that biofilms become more resilient to treatment when formed by multiple organisms. Nonetheless, treatment with EtOH–EDTA is effective against these polymicrobial biofilms.