Identification of Dermatophytes Isolated from Tinea Capitis Patients and Their in vitro Susceptibility to Terbinafine

Abstract

Background: Tinea capitis is an infection caused by dermatophyte fungi of scalp hair follicles and the neighboring skin. Antifungal drugs as terbinafine that are used to treat dermatophytosis direct the ergosterol synthesis pathway. Aim of the work: The current study aimed to identify species and in vitro antifungal susceptibility profile of terbinafine on dermatophytes clinical isolates accompanied by sequencing of the highest minimal inhibitory concentration (MIC) isolates. Patients and methods: The present study is a descriptive cross-sectional study was conducted at Al-Azhar Hospital outpatient clinic, in the period from the 1st of July 2019 to the 15th of July 2020. Samples from 50 patients diagnosed clinically as tinea capitis were taken for microscopic examination by KOH and lactophenol cotton blue and culture on Sabouraud's dextrose agar followed by in vitro susceptibility testing to terbinafine then sequencing of the highest MIC isolates. Results: The isolated dermatophyte species were 16 (32%) isolates of M. canis and 23(46%) isolates of T.violaceum. The MIC varied from 0.003-.092 μg/ml for M.canis and from 0.005-0.116 μg/ml for T.violaceum. It was found in M. canis strain has two base variations with type strain from GenBank whereas T.violaceum strain has ten base variations in the two representative isolates with the highest MIC. Conclusion: T. violaceum was detected as the most common fun‌gal species followed by M. canis. The MIC results to terbinafine showed sensitivity to the antifungal agents. By comparing the M. canis and T. violaceum isolates with type strain on GenBank, some base-pair substitutions were found.