Mycology of Onychomycosis

Onychomycosis is a fungal infection that can occur within the nails of the fingers and the toes. These infections can lead to discoloration and thickening of the nails, as well as separation of the nails from the bed and their splitting, and ultimately nail destruction. Although predominantly caused by dermatophytes, which have keratinolytic properties, several other groups of fungi can also cause this type of infection, including nondermatophyte molds (both hyaline and dematiaceous) and yeasts, such as Candida species. Proper identification of the etiologic agent is important, as it may influence the treatment of these infections. Here, we review the mycology of onychomycosis and describe recent changes in fungal taxonomy that have occurred with several of these fungi.