Treatment of plastic and extracellular matrix components with chlorhexidine or benzalkonium chloride: effect on Candida albicans adherence capacity in vitro

This study investigates the influence of treatment of plastic and extracellular matrix (ECM) proteins with chlorhexidine or benzalkonium chloride on subsequent adherence of Candida albicans. Three concentrations were tested for each antiseptic: (i) chlorhexidine, MIC (6.25-12.5 mg/L), 80 x MIC and 800 x MIC; and (ii) benzalkonium chloride, MIC (3.12 mg/L), 40 x MIC and 1600 x MIC. Chlorhexidine and benzalkonium chloride activities were correlated with the tested concentrations. Antiseptics used at MIC were unable to modify the adherence to plastic or ECM proteins. Chlorhexidine (80 x MIC) induced a decrease in plastic adherence of 31% of the 15 strains used and an increase in ECM protein adherence of 13% of strains. Benzalkonium chloride (40 x MIC) induced a decrease in adherence to ECM proteins or plastic of 13-27% of strains. Our results indicated that the treatment with 1600 x MIC benzalkonium chloride could induce the opposite effect on adherence, depending on the surface: 60% of the strains showed an increase in their adherence to ECM proteins, whereas 93% of the strains showed a decrease in their adherence to plastic. A similar phenomenon was observed after treatment with 800 x MIC chlorhexidine: 60% of the strains showed an increase in their adherence to ECM proteins, whereas 67% showed a decrease in adherence to plastic. Treatment of medical devices with at least 5000 mg/L of chlorhexidine or benzalkonium chloride could therefore reduce C. albicans adherence to plastic surfaces, but would be unable to prevent fungal adherence to ECM proteins.