Evidence for biofilms in onychomycosis.

Onychomycosis is a difficult to treat fungal infection of the nails. The chronic nature of onychomycosis contributes to high recurrence rates and the difficulty in treating both dermatophyte and non-dermatophyte infections. It has been hypothesized that the formation of biofilms, sessile, multicellular communities of fungi surrounded by a protective extracellular matrix, allow for fungi to evade current antifungal therapies and contribute to observed antifungal resistance. This review presents the experimental evidence that has accumulated in recent years implicating biofilms in the pathogenesis of onychomycosis. Dermatophytes, non-dermatophyte molds, and yeasts form biofilms in vitro and a model using ex vivo healthy nail fragments has demonstrated biofilm formation on nails for dermatophyte, Candida, and Fusarium species. Implications for disease management are discussed with further research required to incorporate biofilm formation into future drug/device evaluation and treatment protocols.