Erythrasma is infection of the top layers of the skin caused by the bacterium Corynebacterium minutissimum.
Erythrasma affects mostly adults, especially those with diabetes and those living in the tropics. Erythrasma is most common in the foot, where it causes scaling, cracking, and breakdown of the skin between the 4th and 5th toes. This infection is also common in the groin, where it causes irregularly shaped pink or brown patches and fine scaling especially where the thighs touch the scrotum (in men). The armpits, skinfolds under the breasts or on the abdomen, and the area between the vaginal opening and the anus (perineum) are prone to this infection, particularly among people with diabetes and among obese middle-aged women. In some people, the infection spreads to the torso and anal area.
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.
An antibiotic given by mouth, such as erythromycin or tetracycline, can eliminate the infection. Antibacterial soaps, such as chlorhexidine, may also help. Drugs applied directly to the affected area (topically), such as erythromycin and clindamycin, are also effective. Antifungal creams such as miconazole may be helpful if yeast or fungus is present in the affected areas as well. Erythrasma may recur, necessitating a second treatment.