Prevalence of dermatophytosis in animals and antifungal susceptibility testing of isolated Trichophyton and Microsporum species

Abstract

Dermatophytosis is a frequently encountered dermatological problem in domestic and pet animals which negatively affects animal health and production. This study investigated the prevalence of dermatophytosis in different animals and carried antifungal susceptibility testing in the northern Indian state of Uttarakhand. A total of 157 clinical samples were collected from the animals irrespective of sex and age during a time period of 3 years from December 2016 to December 2019. Direct microscopy, fungal culture, isolation, identification, and antifungal susceptibility testing were carried out. Direct microscopy and in vitro culture were equally efficient in diagnosis of dermatophytosis. The prevalence of dermatophytes ranged between 45 and 53.3% and Trichophyton mentagrophytes was the most abundant species (38%) followed by Microsporum canis (21.5%). All the species observed were isolated from goats and dogs except T. tonsurans and M. nanum, respectively. All the isolated dermatophytes were urease test positive except T. rubrum and T. verrucosum. The hair perforation test was negative for M. audouinii, along with T. rubrum and T. verrucosum, whereas only M. canis was positive for rice grain test. Only T. mentagrophytes, T. rubrum, T. verrucosum, and T. tonsurans were able to show optimum growth at 37 °C. Maximum inhibition of fungal growth was exhibited by clotrimazole and least by fluconazole.

Keywords: Antifungal susceptibility; Dermatophytosis; Direct microscopy; Microsporum; Prevalence; Trichophyton.