Management of cutaneous erythrasma

Corynebacterium minutissimum is the bacteria that leads to cutaneous eruptions of erythrasma and is the most common cause of interdigital foot infections. It is found mostly in occluded intertriginous areas such as the axillae, inframammary areas, interspaces of the toes, intergluteal and crural folds, and is more common in individuals with diabetes mellitus than other clinical patients. This organism can be isolated from a cutaneous site along with a concurrent dermatophyte or Candida albicans infection. The differential diagnosis of erythrasma includes psoriasis, dermatophytosis, candidiasis and intertrigo, and methods for differentiating include Wood's light examination and bacterial and mycological cultures. Erythromycin 250mg four times daily for 14 days is the treatment of choice and other antibacterials include tetracycline and chloramphenicol; however, the use of chloramphenicol is limited by bone marrow suppression potentially leading to neutropenia, agranulocytosis and aplastic anaemia. Further studies are needed but clarithromycin may be an additional drug for use in the future. Where there is therapeutic failure or intertriginous involvement, topical solutions such as clindamycin, Whitfield's ointment, sodium fusidate ointment and antibacterial soaps may be required for both treatment and prophylaxis. Limited studies on the efficacy of these medications exist, however, systemic erythromycin demonstrates cure rates as high as 100%. Compared with tetracyclines, systemic erythromycin has greater efficacy in patients with involvement of the axillae and groin, and similar efficacy for interdigital infections. Whitfield's ointment has equal efficacy to systemic erythromycin in the axillae and groin, but shows greater efficacy in the interdigital areas and is comparable with 2% sodium fusidate ointment for treatment of all areas. Adverse drug effects and potential drug interactions need to be considered. No cost-effectiveness data are available but there are limited data on cost-related treatment issues. A guideline is proposed for the detection, evaluation, treatment and prophylaxis of this cutaneous eruption.