MYCOLOGY OF NAIL DISORDERS

Cases of onychomycosis represent up to 30% of diagnosed superficial fu ngal infections and are caused by three groups of fungi: dermatophytes , yeasts, and nondermatophytic molds. The majority of toenail infectio ns are caused by dermatophytes; Trichophyton rubrum is isolated with t he greatest frequency. In infections of fingernails, Candida species c an be isolated as frequently as the dermatophytes. Of the molds, Scyta lidium species can infect both fingernails and toenails, as well as ad jacent skin, and represent 3% of the nail infections in a temperate co untry such as the United Kingdom but a much higher proportion in tropi cal countries. Other molds such as Scopulariopsis, Acremonium, and Asp ergillus species can infect damaged nails. The isolation of a dermatop hyte is always considered indicative of infection, but the presence of other molds, which may be aerial contaminants, must be interpreted wi th care.