Erythrasma is a bacterial infection usually seen in skin folds. Erythrasma affects mostly adults, especially those with diabetes; it is most common in the tropics. Erythrasma often appears in areas where skin touches skin, such as under the breasts and in the armpits, webs of the toes, and genital area—especially in men, where the thighs touch the scrotum. The infection can produce irregularly shaped pink patches that may later turn into fine brown scales. In some people, the
infection spreads to the torso and anal area.
The bacteria responsible for erythrasma are Corynebacterium minutissimum. This may coexist with a dermatophyte or with Candida albicans. It can infect anyone, but is particularly prevalent in those living in a warm climate or who have diabetes.
Erythrasma does not usually cause any symptoms. It presents as a slowly enlarging area of pink or brown dry skin. Exposure to longwave ultraviolet radiation (such as with a black light or Wood's light) causes the erythrasma to fluoresce a coral-pink colour due to porphyrins released by the bacteria. The diagnosis can be confirmed by a swab or scraping for microscopy and culture.
Although erythrasma may be confused with a fungal infection, doctors can easily diagnose erythrasma because skin infected with Corynebacterium glows coral red under an ultraviolet light. Gently scrubbing the lesions with antibacterial soap may clear the disease. Topical erythromycin gel is very effective as well. In severe cases, your doctor may prescribe oral erythromycin.