Superficial Fungal Infections Health Article

Summary

Superficial fungal infections arise from a pathogen that is restricted to the stratum corneum, with little or no tissue reaction. In this Seminar, three types of infection will be covered: tinea versicolor, piedra, and tinea nigra. Tinea versicolor is common worldwide and is caused by Malassezia spp, which are human saprophytes that sometimes switch from yeast to pathogenic mycelial form. Malassezia furfur , Malassezia globosa , and Malassezia sympodialis are most closely linked to tinea versicolor. White and black piedra are both common in tropical regions of the world; white piedra is also endemic in temperate climates. Black piedra is caused by Piedraia hortae ; white piedra is due to pathogenic species of the Trichosporon genus. Tinea nigra is also common in tropical areas and has been confused with melanoma.

Clinical fungal infections are generally divided into four types: (1) superficial, including tinea versicolor, piedra, and tinea nigra; (2) cutaneous, including onychomycosis, tinea capitis, tinea corporis, tinea barbae, tinea pedis, and candidiasis of skin, mucosa, and nails; (3) subcutaneous, including mycetoma, sporotrichosis, and chromoblastomycosis; and (4) systemic, including North American blastomycosis and cryptococcosis. Superficial fungal infections are defined as infections in which a pathogen is restricted to the stratum corneum, with little or no tissue reaction. Superficial and cutaneous infections are both sometimes regarded as superficial; this Seminar will focus on tinea versicolor, piedra, and tinea nigra.