Clinical Reference / Therapeutic Strategies / Dermatophyte Infections

Dermatophyte Infections


Key Points

  • The term tinea refers to superficial dermatophytic infection of the skin, hair, and/or nails, most commonly by Trichophyton genus, as well as Epidermophyton and Microsporum.
  • Tinea pedis (dermatophyte infection of the skin of the feet), tinea unguium (dermatophyte infection of the nail), tinea capitis (dermatophyte infection of the scalp), and tinea corporis (and its variants) represent the main categories of superficial dermatophytoses.
  • Topical antifungal creams are generally the first-line of treatment of localized superficial disease, with the exception of tinea capitis and onychomycosis (though recently topical treatments for onychomycosis have become available).
  • Superficial Candida infections are covered in a separate section (see Candidiasis).
  • Patients who are prone to recurrent superficial fungal infections may benefit from adjunctive and prophylactic measures including keeping the skin dry to prevent repeated infection and prolonged courses of prophylactic treatment.

Introduction

Epidemiology

Superficial fungal infections of the skin, nails, and hair are extremely common. The dermatophyte species are found in the environment, as well as on animals and humans. Spread occurs primarily from human to human, although contagion of animals to humans, autoinoculation, and spread through fomites are possible modes of transmission in some cases. The most common genera of dermatophytes causing human infection are Trichophyton (with T. rubrum being the most common cause overall), Microsporum, and Epidermophyton.

Pathophysiology

Dermatophytes primarily infect the keratinized outermost layer of the epidermis, as well as the nails and hair. They secrete keratinases that allow them to invade these tissues and provoke an inflammatory response in the host.

Therapy for dermatophyte infections of skin and nails

Most dermatophyte infections of the skin readily respond to topical antifungals. Cases that are refractory, very widespread, recurrent, or involving the hair follicle or nails, may require treatment with oral antifungals. On May 19, 2016, the US FDA (Food and Drug Administration) issued a warning to healthcare professionals to avoid prescribing oral ketoconazole to treat fungal infections of the skin or nails in otherwise healthy patients without life-threatening infection due to concern for toxicities, including hepatotoxicity, adrenal insufficiency, and drug-drug interactions. A similar warning had been issued in 2013, but prescriptions continued for mild fungal infections of the skin and nails, prompting a further warning. Therefore, terbinafine, itraconazole, fluconazole, and griseofulvin (primarily used in children) now represent the systemic antifungals of choice for these infections. A chart summarizing treatment for dermatophyte infections appears below. Detailed management of the various categories of superficial fungal infections follows.

Summary of Treatment for Dermatophyte Infections of Skin and Nails

Disease

First-line treatment

Length of treatment

Tinea capitis (non-inflammatory) Systemic: griseofulvin, terbinafine, itraconazole or fluconazole 4-12 weeks, depending on treatment and initial response
Tinea capitis (inflammatory) Systemic: griseofulvin, terbinafine, itraconazole or fluconazole
+/- corticosteroids
4-12 weeks, depending on treatment and initial response
Tinea of body (corporis, manuum, pedis, cruris) Topical: antifungal cream (imidazole, allylamine)
Systemic: antifungal (severe cases)
1-4 weeks
Onychomycosis Systemic: terbinafine, fluconazole, or itraconazole
Topical: efinaconazole, tavaborole, ciclopirox
Systemic: 6 weeks (fingernails); 3 months (toenails)

Topical: 48 weeks

 

Load more