The role of nondermatophyte molds in onychomycosis: diagnosis and treatment

Onychomycosis is most often caused by dermatophytes. Other agents may cause onychomycosis as well, such as yeasts and nondermatophytic molds (NDMs). Historically NDMs have largely been discounted as merely contaminants, especially when a dermatophyte was present concurrently. NDMs have been shown to be sole etiologic agents, but the extent to which NDMs actually cause nail infections is uncertain. Mixed infections (NDM plus dermatophyte) occur with increasing frequency and there is considerable controversy over the role of NDMs in the presence of a dermatophyte. An isolated NDM seldom meets all the accepted criteria necessary to prove a primary infection. In addition, the criteria for demonstrating infection by an NDM have been the subject of some debate. Better, faster, and cheaper methods of identifying etiologic agents, investigations as to how to demonstrate nail invasion, and studies to determine treatment efficacy, outcome, and necessity are needed.