Molecular Identification and Antifungal Susceptibility Patterns of Clinical Dermatophytes Following CLSI and EUCAST Guidelines

Abstract

Dermatophytes are associated with superficial infections in humans worldwide. The aim of the present study was to determine the species distribution and susceptibility patterns of clinical dermatophytes. Samples received for routine mycological processing from 124 suspected cases attending a dermatologic clinic in a tertiary care hospital were included in the study. On direct microscopy, 74.1% (92/124) were positive and 53.2% (66/124) grew on culture. The isolates were comprised of <i>Trichophyton</i><i>interdigitale</i> (56%) followed by <i>Trichophyton</i><i>tonsurans</i> (25.7%), <i>Trichophyton</i><i>rubrum</i> (7.5%), <i>Trichophyton</i><i>violaceum</i> (4.5%), <i>Microsporum</i><i>gypseum</i> (4.5%), and <i>Trichophyton</i><i>verrucosum</i> (1.5%). Conventional mycological identification was concordant with ITS sequencing except for <i>T.</i><i>mentagrophytes</i>. High minimum inhibitory concentration (MIC) values (geometric mean, >1 µg/mL) were observed for <i>T.</i><i>tonsurans</i> and <i>T.</i><i>rubrum</i> to terbinafine and griseofulvin. This study highlights the shift in epidemiology from <i>T.</i><i>rubrum</i> to <i>T.</i><i>interdigitale</i>. It also raises a concern of high MICs of terbinafine and griseofulvin among our isolates. Surveillance of antifungal susceptibility patterns can provide clinicians with local MIC data that can further aid in guiding better management in relapse cases of dermatomycosis.