Abstract
To understand the significance of proteolytic enzymes in the pathogenesis of dermatophyte infections, we have studied the expression of proteolytic activity in vitro. Cultures were extracted after 1, 2, 3, 4 and 5 weeks of growth and the proteolytic activity measured by a peptide release assay using human stratum corneum as a substrate. Maximum activity was noted at 3 weeks which corresponded to the dissolution of the stratum corneum particles. Isolates of Trichophyton mentagrophytes and Trichophyton rubrum from 42 patients with tinea pedis or tinea unguium were established on 2% glucose peptone plates. Using the peptide release assay it was found that after 3 weeks culture, T. mentagrophytes showed higher activity that T. rubrum in tinea pedis (2044 ± 1067 μg protein released h-1 mg-1, n=13 compared to 828 ± 614 μg protein released h-1 mg-1, n = 13). In tinea unguium, the values at 3 weeks were generally lower. Trichophyton mentagrophytes activity was 837 ± 121 μg protein released h-1 mg-1 (n = 3) compared to 470 ± 271 μg protein released h-1 mg-1 (n=13) for T. rubrum. Thus, as well as a variation in activity between the two species, there appears to be a variation in site in terms of expression of activity.