Erythrasma is an intertriginous infection with Corynebacterium minutissimum that is most common among patients with diabetes and among people living in warmer climates. Diagnosis is clinical. Treatment is with topical antibiotics or oral clarithromycin.
(See also Overview of Bacterial Skin Infections.)
Erythrasma resembles tinea or intertrigo. It most commonly affects the foot, where it manifests as superficial scaling, fissuring, and maceration typically confined to the 3rd and 4th web spaces.
Erythrasma in the groin manifests as irregular but sharply marginated pink or brown patches with fine scaling.
Erythrasma may also involve the axillae, submammary or abdominal folds, and perineum, particularly in obese middle-aged women and in patients with diabetes.
Diagnosis of Erythrasma
Clinical evaluation
Erythrasma fluoresces a characteristic coral-red color under a Wood light due to production of porphyrin by the causative bacterium. Absence of hyphae in skin scrapings also distinguishes erythrasma from tinea.
Differential diagnosis of perianal erythrasma includes perianal streptococcal cellulitis. Perianal streptococcal cellulitis causes pain and bright red erythema solely on perianal skin and lacks fluorescence on Wood light examination. Cultures for group A streptococcus done on skin swabs from affected children are positive.
Treatment of Erythrasma
Topical antibiotics
Oral clarithromycin
Topical erythromycin, clindamycin, mupirocin, fusidic acid, and benzoyl peroxide are effective for patients with localized erythrasma.
For patients with more extensive erythrasma, oral therapy with a single dose of clarithromycin 1 g or erythromycin 250 mg 4 times a day for 14 days is effective.
Recurrence is common.
If Wood light and potassium hydroxide (KOH) or fungal culture are not available to distinguish between erythrasma and superficial fungal infection, a combination of antibacterial and antifungal topical preparations should be considered.
