Extracellular proteinases of Trichophyton rubrum and the clinical picture of tinea.

Summary: 40 clinical isolates of Trichophyton rubrum were tested for production of extracellular proteinases able to digest serum albumin at pH 7,0. In 23 isolates, no proteolysis was demonstrable (—), further 6 isolates showed incomplete proteolysis (±). Only 9 isolates showed definite proteolysis (+) and 2 produced conspicuously large zones of proteolysis in the medium (++): These two isolates came from pustular lesions, atypical for T. rubrum infections. Among the isolates from nails and dry, scaly lesions on palms and soles, non‐proteolysing strains prevailed. Among isolates from interdigital spaces, the +, ± and—strains were equally distributed.