Trichophyton

A genus of pathogenic fungi causing dermatophytosis in humans and animals; species may be anthropophilic, zoophilic, or geophilic, and attack the hair, skin, and nails, and are characterized by their growth in hair. Endothrix species grow from the skin into the hair follicle, penetrate the shaft, and grow into it, producing rows of arthroconidia as the hyphae septate; there is no growth on the external surface of the shaft. Ectothrix species are of two kinds, large spored and small spored. In both, the fungus grows into the hair follicle, surrounds the hair shaft, and penetrates it, but continues to grow both within and outside the hair shaft, producing arthroconidia externally. [tricho- + G. phyton, plant]

- T. concentricum an anthropophilic fungal species that is the causative agent of tinea imbricata; it closely resembles the branching mycelium of T. schoenleinii.

- T. equinum a zoophilic fungal species causing ectothrix infections of hair in horses, from which humans may also be infected; it requires nicotinic acid for growth.

- T. megninii an anthropophilic ectothrix species of dermatophyte fungi with spores in chains, causing infection in humans; it requires histidine, which differentiates it from Microsporum gallinae.

- T. mentagrophytes a zoophilic small-spored ectothrix species of fungi that causes infection of the hair, skin, and nails; it is a cause of ringworm in dogs, horses, rabbits, mice, rats, chinchillas, foxes, and humans (especially tinea pedis with severe inflammation, and tinea cruris).

- T. rubrum a widely distributed anthropophilic fungal species that causes persistent infections of the skin, especially tinea pedis and tinea cruris, and in the nails that are unusually resistant to therapy; it rarely invades the hair, where it is ectothrix in nature; occasional subcutaneous and systemic infections have been reported.

- T. schoenleinii an anthropophilic endothrix species of dermatophyte fungi causing favus in humans; it is endemic throughout Eurasia and Africa and, because of travel, is seen more frequently in the Western Hemisphere; it produces tunnels within the hair shaft that are filled with air bubbles after the hyphae disintegrate.

- T. simii a zoophilic species of fungi that causes infection in rhesus monkeys, dogs, and humans; most infections have had their origin in India.

- T. tonsurans an anthropophilic endothrix species of fungi that causes epidemic dermatophytosis in Europe, South America, and the U.S.; it infects some animals and requires thiamin for growth. It is the most common cause of tinea capitis in the U.S., forming black dots where hair breaks off at the skin surface.

- T. verrucosum a zoophilic species of fungi that causes ringworm in cattle, from which humans can become infected.

- T. violaceum an anthropophilic species of fungi that causes black-dot ringworm or favus infection of the scalp; hair infection is of the endothrix type; usually found in South America, Europe, Asia, and Africa.

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tricho·phy·ton .trik-ə-'fī-.tän, tri-'käf-ə-.tän n

1) cap a genus of ringworm fungi of the family Moniliaceae that have hyaline single-celled spores and are parasitic in the skin and hair follicles of humans and lower mammals see EPIDERMOPHYTON

2) any fungus of the genus Trichophyton

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n.

a genus of fungi, parasitic in humans, that frequently infect the skin, nails, and hair and cause ringworm. See also dermatophyte.

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Tri·choph·y·ton (tri-kofґĭ-ton) [tricho- + Gr. phyton plant] a genus of Fungi Imperfecti of the form-class Hyphomycetes, form-family Moniliaceae, consisting of flat, branched filaments. Many species are dermatophytes and attack the skin, nails, and hair, and most are either of the large-spored ectothrix or endothrix type. As the perfect (sexual) stages are identified they are classified in the genus Arthroderma.