• Clinical science

Dermatophyte infections (Dermatophytoses)

Summary

Dermatophyte infections, also known as tinea, are the most common fungal infections of the skin, hair, and nails. The term “dermatophyte” refers to fungal species that infect keratinized tissue, and includes members of the Trichophyton, Microsporum, and Epidermophyton genera. Tinea are classified based on their location (e.g., tinea pedis occurs on the feet and tinea capitis on the scalp). Children and immunocompromised individuals are more likely to contract tinea infections, especially tinea capitis. However, people of all ages may suffer from tinea pedis or tinea unguium. The clinical features of dermatophyte infection include pruritus, scaling, and erythema. The best initial test for the diagnosis of dermatophyte infection is potassium hydroxide (KOH) preparation, which allows segmented hyphae to be seen on microscopy. Generally, the treatment for dermatophyte infections is topical antifungals. Oral antifungals (e.g., terbinafine, griseofulvin) are always used in tinea capitis and are also used for severe, refractory cases of other kinds of tinea. Concomitant tinea infections in household members or pets should be treated as well.

Tinea versicolor, despite its name, is not caused by dermatophytes and is discussed in another article.

Overview

General [1]

Diagnosis of dermatophyte infections

Treatment of dermatophyte infections [4]

Because topical treatments are unable to penetrate the hair shaft, systemic therapy with oral antifungals such as griseofulvin or terbinafine is necessary in tinea capitis.

To prevent tinea infections from spreading, contaminated objects should not be shared (e.g., shoes, combs). Other members of the household and pets who are infected should also receive treatment!

Tinea

Tinea pedis (athlete's foot)/tinea manuum

Tinea corporis (ringworm)

  • Definition: dermatophyte infection affecting a location other than feet, scalp, nails, and groin; mostly the arms and upper body.
  • Predisposing factors
    • Contact with infected individuals or animals
    • Moist environments (e.g., public swimming pools)
  • Pathogen: most commonly T. rubrum
  • Clinical presentation [6]
  • Diagnosis and treatment: See “Overview” section above.

Tinea capitis

Favus

  • Definition
    • Chronic infection caused by T. schoenleinii
    • Severe form of tinea capitis
  • Epidemiology: more common in Africa, the Middle East, and the Mediterranean
  • Clinical presentation: formation of yellow, malodorous crust with subsequent scarring alopecia
  • Treatment

Tinea unguium (onychomycosis)

The successful treatment of onychomycosis involves not only the elimination of sources of infection, but also the promotion of personal hygiene, the disinfection of footwear, and the elimination of predisposing factors.

Tinea cruris (jock itch)

  • Definition: fungal infection of the inguinal area
  • Pathogen: most commonly T. rubrum
  • Clinical presentation
  • Diagnosis and treatment: See “Overview” section above.


References:[6][7][7][5][8]

Differential diagnoses

The differential diagnoses listed here are not exhaustive.