erythrasma

Erythrasma is a chronic, superficial bacterial skin infection caused by Corynebacterium minutissimum. It most commonly affects intertriginous areas such as the axillae, groin, and toe webs, particularly in adults living in warm, humid climates or in individuals with obesity, diabetes, or other immune or skin conditions. The infection presents as well-defined reddish-brown patches with fine scaling, which may be asymptomatic or mildly itchy.

The condition can resemble fungal infections or intertrigo, leading to misdiagnosis. A key diagnostic feature is fluorescence under a Wood’s lamp, where the affected skin emits a coral-red glow due to porphyrin production by the bacteria. Microscopic examination or culture can reveal Gram-positive, pleomorphic rods with a distinctive appearance; culture is not always necessary. The diagnosis is often clinical and confirmed by Wood’s lamp findings.

Treatment typically involves topical or oral antibiotics. Topical options include erythromycin or clindamycin preparations applied to the affected areas for several weeks. If the infection is extensive or recurs, systemic antibiotics such as erythromycin, doxycycline, or clarithromycin may be used for a short course. Good hygiene, drying of skin folds, and management of contributing factors help reduce recurrences. In many cases, treating both affected areas and any close contacts may prevent reinfection.

Prognosis is generally favorable with appropriate therapy. Recurrence is relatively common, so maintenance measures such as keeping skin dry and weight management can be important. Erythrasma responds well to standard antibacterial therapies, distinguishing it from dermatophytoses and candidiasis that may mimic its appearance.