Dermatophytes: In an Artificial Environment

Abstract

The author has determined that Trichophyton mentagrophytes and T. rubrum in keratinous particles are viable for several months. A total of 110 colonies was isolated from a hospital environment: 98 (90%) colonies of T. mentagrophytes, 6 (5%) colonies of T. rubrum and 6 (5%) other colonies. This low percentage of T. rubrum is noteworthy since a recent 6-year survey on the epidemiologic investigation of tinea pedis showed T. rubrum was twice as often the cause of tinea pedis as T. mentagrophytes. Dermatophytes in the environment have been believed to be primarily distributed in the keratinous particles shed from the feet of persons with tinea pedis. But cellophane adhesive tapes applied to the planta of 20 tinea pedis patients revealed that fungal filaments were detected not only inside squama but also outside squama. Consequently, T. rubrum outside squama is considered to be viable for only several days in the environment.
T. mentagrophytes was isolated from 75 percent of tinea pedis which appeared to develop during inpatient visits. This finding suggests that T. mentagrophytes which is isolated at a relatively high frequency in communal environments could be a source of infection.