Suitability of hair type for dermatophytes perforation and differential diagnosis of T. mentagrophytes from T. verrucosum.

Most of the dermatophyte species have the ability to perforate hair structure and consume its contents of keratin through secretion of keratinase enzyme. Two clinical isolated species of dermatophytes were diagnosed as Trichophyton mentagrophytes var. granulosum and Trichophyton verrucosum. To determine the perforation ability, the isolated fungi were incubated with the hair of four different animals (rabbit, rat, cow and cat) and human hairs with three different colours (black, albino and bleached yellow) for different periods. Variable perforating ability of T. mentagrophytes was shown in rat hair and all types of human hair after 15 days, while other mammalian hairs exhibited resistance to this fungal activity. On the other hand, T. verrucosum was revealed a slow perforating ability, which needed a long time (60 days) for most of tested hairs. Perforation of human black hair could be considered a diagnostic test for differentiation between T. mentagrophytes and T. verrucosum. In conclusion, the treated or untreated human hair was considered more suitable to use as a source of keratin for the growth of dermatophytes than animal hairs. The human black hair was a best type of hair to use in the perforating test for differentiation between T. mentagrophytes and T. verrucosum.