Efficacy of antiseptics and disinfectants on clinical and environmental yeast isolates in planktonic and biofilm conditions

The aim of this study was to evaluate the efficacy of five antiseptics, three surface disinfectants and UV radiation against a wide range of clinical and environmental yeast isolates. Their efficacy against pure cultures, yeast mixtures and biofilms (prepared by culturing yeasts in Sabouraud broth containing a final concentration of 8% glucose) was tested. Three clinical isolates of Candida albicans, Cryptococcus neoformans and Rhodotorula rubra, and two environmental isolates of Candida albicans and Cryptococcus uniguttulatus were selected. For seven out of eight biocides tested (Betadine, Dermacide, Chlorhexidine, Dosisepsine, hydrogen peroxide, sodium hypochlorite, 70% alcohol, 0.5% Ecodiol) and for UV radiation, susceptibility did not differ according to genus, species or origin. Hydrogen peroxide, 0.25% Ecodiol and UV radiation were ineffective against the five isolates tested. On pure planktonic cultures, and, to a lesser extent, on free-living yeast mixtures, the other products were active and were then tested against biofilms: eight out of nine biocides were ineffective. Chlorhexidine at 0.5% was the only fungicidal agent on pure cultures, yeast mixtures and biofilms. The importance of the test method, including agent concentration, is discussed.