Molecular identification of isolates of the <i>Trichophyton mentagrophytes</i> complex

<b>Background:</b> The <i>Trichophyton mentagrophytes</i> complex is the second most common causal agent of dermatophytosis. It comprises five species-<i>T. mentagrophytes</i>, <i>T. interdigitale</i>, <i>T. erinacei</i>, <i>T quinckeanum,</i> and <i>T. benhamie,</i> as well as nine different genotypes of <i>T. mentagrophytes</i> / <i>T. interdigitale</i>-which are morphologically similar; however, their susceptibility to antifungal agents may differ. For targeted therapy and better prognosis, it is important to identify these species at a molecular level. However, since many hospitals lack molecular methods, the actual aetiology of dermatophytosis caused by this complex remains unknown. <b>Objective:</b> To characterize 55 anthropophilic isolates of the <i>T. mentagrophytes</i> complex recovered from a dermatological centre in Yucatán, Mexico. <b>Material and methods:</b> Fifty-five isolates of the <i>T. mentagrophytes</i> complex were obtained from patients with <i>tinea capitis</i>, <i>tinea pedis</i>, <i>tinea corporis</i>, <i>tinea barbae</i>, and <i>tinea unguium</i>. They were characterized by their colonial and microscopic morphology on Sabouraud dextrose agar (SDA) and through the sequencing of a fragment from the region ITS1-5.8S-ITS2. <b>Results:</b> All colonies grown on SDA were white. Forty-six isolates formed colonies with a powdery texture, while nine isolates formed colonies with a velvety texture. The micromorphological features were typical of the <i>T. mentagrophytes</i> complex. The molecular analysis revealed that 55 isolates were microorganisms that belonged to the <i>T. mentagrophytes</i> complex, that 46 formed powdery colonies representing <i>T. mentagrophytes</i>, and that the other nine isolates that formed velvety colonies represented <i>T. interdigitale</i>. The latter nine isolates were obtained from patients with <i>tinea pedis</i>, <i>tinea corporis</i>, and <i>tinea unguium</i>. <b>Conclusions:</b> The colony morphology on SDA led to the identification of 46 isolates as <i>T. mentagrophytes</i> and nine isolates as <i>T. interdigitale</i>. At a molecular level, the species identified by their morphology were identified only as <i>T. mentagrophytes</i> complex.