Erythrasma is a chronic superficial localized skin infection caused by bacteria called Corynebacterium minutissimum. Erythrasma is more common in warm, humid climates, or in individuals with poor hygiene, increased sweating, obesity, diabetes, advanced age and poor immune function. It is more commonly located in intertrigineous areas or skin folds including the groin, armpit, intergluteal fold, inframammary, and periumbilical areas. Patients are usually asymptomatic, but mild itchiness or burning may be present especially if they are located in the groin area.

Initially the skin lesions are well-defined pink patches covered with fine scales and wrinkling. Later the pink to red color fades and the affected area becomes brown and scaly.

There are also two distinct variants of erythrasma, which are called generalized and interdigital. The interdigital variant is the most common bacterial infection of the feet that presents as fissuring or scaling of the interspaces of the toes without any symptoms. The fissures and scaling most commonly occur between the fourth or fifth digit (little toe) of the feet. The generalized variant is the most common seen in diabetes (diabetes mellitus type 2) in which the skin lesions extend beyond the intertrigineous areas.

Diagnosis can be made by a dermatologist using a Wood’s lamp in the office. Wood’s lamp is a non-invasive diagnostic tool that shines ultraviolet light onto the skin. In erythrasma, a bright coral-red fluorescence is seen when the lamp is shined over the affected area. Another way to diagnose erythrasma is by culturing the skin scrapings from the lesion.

Treatment usually consists of keeping the area clean and dry with antibacterial soaps and aluminum chloride topical solution. An antibacterial solution or cream such as clindamycin HCL solution, erythromycin or miconazole cream can be prescribed to eradicate the bacteria. For a more aggressive treatment, oral antibiotics such as erythromycin can also be used with successful results.