Isolation, Identification And Antifungal Susceptibility Of Dermatophytes From Clinical Samples – One Year Study

Abstract

INTRODUCTION: Infection of the keratinized tissues (hair, skin & nail) in man and animals by keratinophilic fungi (dermatophytes) results in dermatophytosis. Dermatophytes are a group of closely related keratinophilic fungi that can invade keratinized tissue of humans and animals such as skin, hair and nails causing dermatophytosis. Dermatophytes consist of three genera namely Trichophyton, Microsporum, and Epidermophyton. Worldwide the most common cause of tinea pedis, tinea unguium (onychomycosis), tinea cruris, tinea mannum, tinea corporis, and tinea faciei is Trichophyton rubrum. AIMS AND OBJECTIVES: • To isolate and identify the fungi causing dermatophytosis. • To perform antifungal susceptibility testing of the fungal isolates by microbroth dilution method. MATERIAL AND METHODS: The study was a cross sectional study. All clinically diagnosed cases of Dermatophytosis attending Out Patient department of Dermatology, Venerology and Leprosy of Dr. Prabhakar Kore Charitable hospital was included in the study and those who were already on treatment for Dermatophytosis were excluded from the study. 100 samples of skin hair and nail were collected and subjected to KOH. Culture was done on SDA with and without antibiotics. Isolates were identified by morphology, LCB preparation and slide culture. Antifungal susceptibility by microbroth dilution method was carried out to determine the MIC values for Ketoconazole, Sertaconazole, Terbinafine and Clotrimazole. RESULTS: In our study 100 (skin-77, nail-20 and hair-3) samples were included out of which 63 samples were KOH positive and 37 were KOH negative. 88 samples were culture positive and 22 were culture negative. T. rubrum was the commonest fungus isolated (33) followed by T. mentagrophytes (20), T. tonsurans (8) and M. gypseum (2). Other isolates included Acremonium species, Curvularia species and Penicillium species (17). MIC of T.rubrum against Terbinafine was (0.03-0.5µg/ml), Clorimazole (0.03-0.62µg/ml), Sertaconazole (0.03-0.62µg/ml), Ketoconazole (0.03-4µg/ml). CONCLUSION In our study T.rubrum was the commonest dermatophyte isolated. MIC of T.rubrum against Terbinafine was (0.03-0.5µg/ml), Clorimazole (0.03-0.62µg/ml), Sertaconazole (0.03-0.62µg/ml), Ketoconazole (0.03-4µg/ml). The other isolated species had comparable MIC. Susceptibilty of T.mentagrophytes and T.tonsurans against Ketoconazole was in the higher range. Periodic evaluation of Antifungal Susceptibility Testing is necessary to know the MIC range of prevailing strains against commonly used drugs so as to guide the empirical treatment of dermatophytosis.