Early detection and identification of Trichophyton verrucosum.

A new medium for the early detection and identification of Trichophyton verrucosum has been formulated. The key ingredients of the medium are 4% casein and 0.5% yeast extract. T. verrucosum is recognized by its early hydrolysis of casein and very slow growth. Microconidia were produced by 19 out of 35 isolates (54%), and macroconidia were produced by 8 out of 35 isolates (23%). All isolates formed chains of chlamydospores at 37 degrees C, and 24 out of 35 isolates formed chains at 28 degrees C. Nutritional requirements of all 35 strains of T. verrucosum were confirmed. The medium was evaluated by isolating 570 suspected T. verrucosum from skin scrapings. The early detection of hydrolysis, formation of characteristic chains of chlamydospores, and restricted slow growth of this dermatophyte differentiate it from T. schoenleinii.