Phenotypic and Genotypic Identification of Dermatophytes from Mexico and Central American Countries.

Dermatophytes are fungi included in the genera Trichophyton , Microsporum , Epidermophyton , Nannizzia , Paraphyton , Lophophyton , and Arthroderma . Molecular techniques have contributed to faster and more precise identification, allowing significant advances in phylogenetic studies. This work aimed to identify clinical isolates of dermatophytes through phenotypic (macro- and micromorphology and conidia size) and genotypic methods (sequences of ITS regions, genes of β tubulin ( BT2 ), and elongation factor α ( Tef-1α )) and determine the phylogenetic relationships between isolates. Ninety-four dermatophyte isolates from Costa Rica, Guatemala, Honduras, Mexico, and the Dominican Republic were studied. The isolates presented macro- and micromorphology and conidia size described for the genera Trichophyton , Microsporum , and Epidermophyton . Genotypic analysis classified the isolates into the genera Trichophyton (63.8%), Nannizzia (25.5%), Arthroderma (9.6%), and Epidermophyton (1.1%). The most frequent species were T. rubrum (26 isolates, 27.6%), T. interdigitale (26 isolates, 27.6%), and N. incurvata (11 isolates, 11.7%), N. gypsea and A. otae (nine isolates, 9.6%), among others. The genotypic methods clarified the taxonomic status of closely related species. For instance, the ITS and BT2 markers of T. rubrum / T. violaceum did not differ but the Tef-1α gene did. On the other hand, the three markers differed in T. equinum / T. tonsurans . Therefore, the ITS, BT2 , and Tef-1α genes are useful for typing in phylogenetic analyses of dermatophytes, with Tef-1α being the most informative locus. It should be noted that isolate MM-474 was identified as T. tonsurans when using ITS and Tef-1α , but when using BT2 , it was identified as T. rubrum . On the other hand, no significant difference was found when comparing the methods for constructing phylogenies, as the topologies were similar.