FUNGAL INFECTIONS OF THE SKIN

Mycotic infections are traditionally divided into two principal groups—superficial and deep. 

The diagnosis of fungal infections of the skin is usually based on the location and characteristics of the lesions and on the following laboratory examinations: (1) Direct demonstration of fungi in 10% KOH of scrapings from suspected lesions. “If it's scaly, scrape it” is a time-honored maxim. (2) Cultures of organisms from skin scrapings. (3) Histologic sections of nails stained with periodic acid-Schiff (Hotchkiss-McManus) technique may be diagnostic if scrapings and cultures are negative.

Principles of Treatment
In general, treatment follows a diagnosis confirmed by KOH preparation or culture, especially if systemic antifungal therapy is to be used. Many other diseases cause scaling, and use of an antifungal agent without a firm diagnosis makes subsequent diagnosis more difficult. In general, fungal infections are treated topically except for those involving the nails or those deep in hair follicles on the face or body.
Griseofulvin is safe and effective for treating dermatophyte infections of the skin (except for the scalp and nails). Itraconazole, an azole antifungal, accumulates in the nail plate from the matrix and nail bed and persists for 3 months after oral administration is discontinued.
Terbinafine is an allylamine oral antifungal. It has excellent activity against dermatophytes. In vitro activity against yeast forms is variable, but the drug is active against hyphal forms. It is well delivered to the nail plate and persists in the nail for 6–9 months after treatment has ended.
Fluconazole has excellent activity against yeasts and may be the treatment of choice for many forms of mucocutaneous candidiasis. Fluconazole is less effective than itraconazole or terbinafine for the treatment of dermatophytosis.
Itraconazole, fluconazole, and terbinafine can all cause elevation of liver function tests and—though rarely in the dosing regimens used for the treatment of dermatophytosis—clinical hepatitis. Ketoconazole is no longer recommended for the treatment of dermatophytosis (except for tinea versicolor) because of the higher rate of hepatitis when it is used for more than a month.
General Measures & Prevention
Since moist skin favors the growth of fungi, dry the skin carefully after bathing or after perspiring heavily. Talc or other drying powders may be useful. The use of topical corticosteroids for other diseases may be complicated by intercurrent tinea or candidal infection, and topical antifungals are often used in intertriginous areas with corticosteroids to prevent this.
 much more difficult to cure), pyoderma, and dermatophytid.
Prevention
Treat infected household pets (microsporum infections).
 

Treatment
LOCAL MEASURES
The following applied topically are effective against dermatophyte infections other than those of the nails: miconazole, 2% cream; clotrimazole, 1% solution, cream, or lotion; ketoconazole, 2% cream; econazole, 1% cream or lotion; sulconazole, 1% cream; oxiconazole, 1% cream; ciclopirox, 1% cream; naftifine, 1% cream or gel; butenafine cream; and terbinafine, 1% cream. Miconazole, clotrimazole, butenafine and terbinafine are available over the counter. Allylamines (especially terbinafine and butenafine) require shorter courses and lead to the most rapid response and prolonged remissions. Treatment should be continued for 1–2 weeks after clinical clearing. Betamethasone dipropionate with clotrimazole (Lotrisone) is overused by nondermatologists. In general, short-term use of betamethasone-clotrimazole does not justify the expense, and long-term improper use may result in side effects from the high-potency corticosteroid component, especially in body folds. Cases of tinea that are clinically resistant to this combination have been reported.
SYSTEMIC MEASURES
Griseofulvin (ultramicrosize), 250–500 mg twice daily, is used. Typically, only 4–6 weeks of therapy are required. Itraconazole as a single week-long pulse of 200 mg daily is also effective in tinea corporis. Terbinafine, 250 mg daily for 1 month, is an alternative.
Prognosis
Body ringworm usually responds promptly to conservative topical therapy or to griseofulvin by mouth within 4 weeks.

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