Characterization and antifungal susceptibility of Trichophyton mentagrophytes isolated from a goat presented with severe dermatophytosis in Zaria, Nigeria

Dermatophytosis is a contagious skin disease affecting domestic and wild animals with considerable zoonotic  significance. The disease is caused by fungi known as dermatophytes in the genera Trichophyton, Microsporum and  Epidermophyton. A goat was observed with circumscribed alopecic, highly inflammatory, thickly crusted skin lesions on  the head region, especially around the eyes. Skin scraping, including hair pullouts, was aseptically obtained and  processed for direct examination, isolation and microscopic identification of etiologic agent and supplemented with  urease test. The isolate was tested for its susceptibility to fluconazole, griseofulvin, itraconazol and ketoconazole. Direct  examination revealed hyaline, septate hyphae in skin scales and chains of endothrix spores within hair shafts,  suggesting Trichophyton infection. Colonies on Sabouraud’s dextrose agar were white, flat and granular. Microscopic examination of the isolate revealed many oval micro-conidia arranged in grapelike clusters with multi-septate, club- shaped, thin, and smooth-walled macroconidia typical of Trichophyton mentagrophytes. The isolate was urease-positive  and sensitive to itraconazole and ketoconazole but resistant to fluconazole and griseofulvin. It was concluded that T.  mentagrophytes was the cause of the severe skin lesions in the goat. The need to perform antifungal susceptibility  testing on dermatophytes isolated from clinical specimens for effective management of dermatophytosis was  emphasized.