In vitro and ex vivo biofilms of dermatophytes: a new panorama for the study of antifungal drugs.

This study describes an ex vivo model that creates an environment for dermatophyte biofilm growth, with features that resemble those of in vivo conditions, designing a new panorama for the study of antifungal susceptibility. Regarding planktonic susceptibility, MIC ranges were 0.125-1 µg ml-1 for griseofulvin and 0.000097-0.25 µg ml-1 for itraconazole and terbinafine. sMIC50 ranges were 2->512 µg ml-1 for griseofulvin and 0.25->64 µg ml-1 for itraconazole and terbinafine. CLSM images demonstrated a reduction in the amount of cells within the biofilm, but hyphae and conidia were still observed and biofilm biomass was maintained. SEM analysis demonstrated a retraction in the biofilm matrix, but fungal structures and water channels were preserved. These results show that ex vivo biofilms are more tolerant to antifungal drugs than in vitro biofilms, suggesting that environmental and nutritional conditions created by this ex vivo model favor biofilm growth and robustness, and hence drug tolerance.