Diversity of ITS Genotypes in Trichophyton mentagrophytes Species Complex Isolates Causing Tinea Corporis and Tinea Capitis: A Multicenter Study in France

The Trichophyton mentagrophytes complex currently comprises three species (T. mentagrophytes, T. interdigitale, and T. indotineae) and exhibits substantial diversity in ITS region sequences. Within this complex, Trichophyton indotineae and T. mentagrophytes ITS genotype VII have recently emerged as important public health concerns. The aim of the study was to describe the diversity of species and ITS genotypes among human clinical isolates belonging to the T. mentagrophytes complex recovered from glabrous skin and scalp samples in France. All isolates belonging to the T. mentagrophytes complex obtained from glabrous skin and scalp samples collected by three private clinical laboratories located in three French regions were sequenced for the ITS region. Clinical data were collected to compare patient characteristics according to ITS genotype. Among the 92 isolates, 62 (67.4%) corresponded to T. mentagrophytes sensu stricto, 21 (22.8%) to T. indotineae, and 9 (9.8%) to T. interdigitale. Among T. mentagrophytes sensu stricto isolates, five ITS genotypes were identified, in decreasing order of frequency: II*, III*, VII, III, and IV. Trichophyton mentagrophytes ITS genotype VII accounted for 16.3% of isolates within the T. mentagrophytes species complex and was isolated exclusively from adult men, unlike the other ITS genotypes. Twelve of the 21 T. indotineae isolates grew on a terbinafine screening medium and harbored the F397L or L393S substitution in the SQLE sequence. The emerging pathogens T. indotineae and T. mentagrophytes ITS genotype VII together account for 39.1% of T. mentagrophytes species-complex isolates identified in three private laboratories In France and infecting glabrous skin or scalp.