dermatofyter

Dermatophytes are a group of keratinophilic fungi that cause infections of keratinized tissues in humans and animals. They obtain nutrients from keratin and colonize the skin, hair, and nails. The genera most commonly implicated in human disease are Trichophyton, Microsporum, and Epidermophyton. Infections caused by dermatophytes are collectively known as dermatophytosis or tinea, with names based on the body site, such as tinea corporis (body), capitis (scalp), cruris (groin), pedis (foot), and tinea unguium for nails.

Transmission occurs through direct contact with an infected person or animal, or via contaminated objects and surfaces. Zoonotic transmission from domestic animals is common for several species, including Microsporum canis. Dermatophyte infections thrive in warm, moist environments and can spread in communal areas such as locker rooms and showers.

Clinically, infections present with pruritic, scaly, ring-shaped or annular lesions on the skin; scalp involvement may cause hair loss and scaling; tinea pedis typically causes itching and fissuring between the toes; nail infections are often slow to resolve. Diagnosis is usually clinical and supported by microscopy of skin scrapings or nail clippings using potassium hydroxide, fungal culture, and, when available, molecular methods. A Wood lamp can aid detection for certain species but is not universally reliable.

Treatment depends on site and extent. Limited skin infections may respond to topical antifungals such as azoles (clotrimazole, miconazole) or allylamines (terbinafine). Infections of the scalp or nails, extensive disease, or immunocompromised patients require systemic antifungals such as terbinafine, itraconazole, or fluconazole for several weeks to months; griseofulvin is used less commonly today. Prevention focuses on good hygiene, keeping skin dry, avoiding sharing personal items, and treating infected animals.