Interdigital foot infections: Corynebacterium minutissimum and agents of superficial mycoses

Interdigital foot infections are mostly caused initially by dermatophytes, yeasts and less frequently by bacteria. Erythrasma caused by Corynebacterium minutissimum can be confused with superficial mycoses. The aim of the study was to determine the prevalence of the etiologic agents of superficial mycoses and the frequency of Corynebacterium minutissimum in interdigital foot infections. All the samples obtained from the 121 patients with interdigital foot infections were examined directly with the use of 20% potassium hydroxide mounts and Gram stain under the microscope and cultured on Sabouraud's dextrose agar plates. In identification of superficial mycoses, the rate was found to be 14% with the cultural method and 14% with direct microscopic examination. Using a combination of direct microscopic examination and culture, a 33.8% ratio was achieved. In the culture of these samples, the most isolated factor was Trichophyton rubrum (33.7%). In 24 of the patients (19.8%) Corynebacterium minutissimum was detected by Gram staining, in 6 of these patients Trichophyton rubrum was found, Trichophyton mentagrophytes was found in 2 and Trichosporon spp. was found in 1. The examination of interdigital foot lesions in the laboratory, the coexistence of erythrasma with dermatophytes and yeast should be considered.

The Incidence and Culture of Erythrasma in Korea / 대한피부과학회지

BACKGROUND: The authors did not find any study about erythrasma in Korea, where as there are several studies about the incidence and bacteriology of erythrasma in some areas. Failure to differentially diagnose the clinical entities of tinea pedis versus erythrasma can lead to mistreatment and disability because of the clinical similarities. OBJECTIVE: This study was carried out to investigate the incidence of erythrasma according to the seasons and sites, to determine the useful culture media, and to evaluate the antibiotic sensitivities and the treatment responses. METHODS: The incidence of erythrasma was investigated among the unselected dermatologic patients. The axillae, groins and toewebs were examined under Wood's light. The scale showing characteristic coral-red fborescence was Gram-stained and Corynebacterium minutissimnm was cultured using Loeffler slant media, Brucella blood agar plates and usual blood agar plates. RESULTS: Clinical erythrasma was found in 26.7% of the 240 patients examined. The incidences of erythrasma in summer and fall were higher than winter In the bacteriologic study Gram positive cocco-bacilli were found in all erythrasma patients and Corynebacterium minutissimum was cultured and identified in 24 0%. Most of cultured causative organisms were sensitive to usual antibiotics in the clinical uses. The average interval from the oral administration of erythrasma to the loss of coral-red fluorescence was 4.1 weeks, and the patients in severe erythrasma group were needed more time(2.2 weeks) for clinical improvement than the patients in mild one. CONCLUSION: Erythrasma is common in the dermatologic patients and it is important to differentially cliagnose the clinical entities of tinea pedis versus erythrasma.