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Fungal Infections

The dermatophytes metabolize the keratin of the skin, hair, and nails. Hydration and occlusion of the skin facilitate infection. Although dermatophyte infections routinely affect persons who are otherwise healthy, immunocompromised patients are particularly susceptible. Bizarre presentations and failure to respond.

I. Diagnostic Evaluation of Dermatophyte Infections

A. Potassium Hydroxide Exam. Accurate diagnosis of dermatophyte infections requires a potassium hydroxide (KOH) examination. Scrapings from involved skin or nail are placed in a drop of 20% potassium hydroxide (KOH) solution on a glass slide; a coverslip is applied, and the preparation is heated gently over an alcohol lamp. Examination under a microscope reveals the septate, branching, dermatophyte infections, dermatophytes, ringworm, ring worm, tinea threadlike hyphae characteristic of dermatophytes. KOH examination of hair reveals small spores. If potassium hydroxide exam is negative, the scales may be cultured on a fungal medium designed for ringworm and ring worm.

II. Tinea Pedis (athlete's foot)

A. The acute form of tinea pedis is characterized by Treatment of Dermatophyte Infections, ringworm ring worm, tinea sudden onset of an erythematous vesicular or bullous eruption, which is intensely pruritic and sometimes painful. It occurs interdigitally and on the soles of the feet. Acute attacks are self-limited, but recurrences are common. A sterile vesicular "id eruption" sometimes appears concomitantly on the hands.

B. The chronic form of tinea pedis is Interdigital fissures are common. Untreated, the eruption persists indefinitely. The palm on the dominant-handed side is often similarly involved ("one-hand, two-feet disease").

C. Tinea pedis is caused by Trichophyton mentagrophytes or Trichophyton rubrum. KOH examination of skin scrapings show septate hyphae. Secondary staphylococcal infections are common.

D. Management of Tinea Pedis

III. Onychomycosis (tinea unguium)

A. Onychomycosis affect the fingernails and toenails. Nail lesions of psoriasis, eczematous eruptions and ischemic arterial disease can mimic onychomycosis. The KOH test or a culture is essential to establish the proper diagnosis.

B. Onychomycosis is cause by T rubrum, and some degree of tinea pedis is usually also present. The disease usually begins at the corner of the nail as a yellowish discoloration. As it spreads, the nail begins to separate from its bed distally, resulting in irregular nail dystrophy.

IV. Tinea Cruris

V. Tinea capitis