Am Fam Physician. 2003;67(2):254
to the editor: I read with great interest the article entitled, “Common Bacterial Skin Infections,”1 and I would like to make an additional comment concerning cutaneous erythrasma and its causative organism, Corynebacterium minutissimum.2 Erythrasma is a cutaneous disorder of which the lesions may present as patches that are asymptomatic and well defined, or irregular in shape and size and red in color. The lesions may become brownish and appear slightly raised from the surrounding skin with the appearance of central clearing. Interdigital erythrasma is a common bacterial infection of the foot.
In some studies, up to 30 percent of patients with interdigital erythrasma have been found to have a coexisting dermatophyte or Candida albicans infection, usually noted in the third and fourth interspaces.2 Areas of the body that favor C. minutissimum growth are moist, occluded intertriginous areas such as the axillae, inframammary areas, and interspaces of the toes, as well as the intergluteal and crural folds. Factors such as a warm climate, poor hygiene, obesity, hyperhidrosis, advanced age, compromised host status, and diabetes mellitus also play a role in the occurrence of this organism.
The differential diagnosis of erythrasma includes psoriasis, dermatophytosis, candidiasis, and intertrigo. Examination with Wood's light shows a coral-red fluorescence and is the diagnostic procedure of choice; however, microscopic examination and cultures may be required in certain instances when the Wood's light examination is negative, yet the organism is still suspected and a detection and treatment algorithm has been proposed.2
The most effective treatment is erythromycin (250 mg, four times daily for 14 days) with cure rates (both clinical and bacteriologic) as high as 100 percent. In patients with interdigital involvement or hidden reservoirs, some form of local therapy is recommended, such as clindamycin (Cleocin) or Whitfield's ointment applied once daily during the course of oral therapy and continued for two weeks after the physical clearance of these areas. Interestingly, a literature search of the treatment of interdigital erythrasma, antifungal agents that have been proposed for topical treatment, such as tolnaftate (Tinactin), haloprogin (Halotex), clotrimazole (Lotrimin), bifonazole (Canesten), and econazole (Spectazole), yield poor and inconclusive results in the treatment of this condition.2