Antifungal resistance of candidal biofilms formed on denture acrylic in vitro.

Denture biofilms represent a protective reservoir for oral microbes. The study of the biology of Candida in these biofilms requires a reliable model. A reproducible model of C. albicans denture biofilm was developed and used to determine the susceptibility of two clinically relevant C. albicans isolates against 4 antifungals. C. albicans, growing as a biofilm, exhibited resistance to amphotericin B, nystatin, chlorhexidine, and fluconazole, with 50% reduction in metabolic activity (50% RMA) at concentrations of 8, 16, 128, and > 64 microg/mL, respectively. In contrast, planktonically cultured C. albicans were susceptible (50% RMA for the same antifungals was obtained at 0.25, 1.0, 4.0, and 0.5 microg/mL, respectively). In conclusion, results obtained by means of our biofilm model show that biofilm-associated C. albicans cells, compared with cells grown in planktonic form, are resistant to antifungals used to treat denture stomatitis.