Genotype structure of Trichophyton mentagrophytes complex from companion animals in France reveals restricted diversity

The Trichophyton mentagrophytes complex includes pathogens of major relevance in both human and veterinary medicine. Despite growing knowledge of ITS diversity within the complex, data on circulating genotypes in animals remain scarce. We analyzed 348 T. mentagrophytes isolates obtained from companion animals in France in 2020 to describe ITS genotype distribution and assess the presence of T. indotineae and T. mentagrophytes ITS-genotype VII. Eight ITS genotypes were identified, with genotype III* largely predominant (62.4%), followed by genotypes III (22.4%) and II* (8.6%). No significant difference in genotype distribution was observed between cats and dogs. Genotype XXIV was exclusively detected in the three chinchilla isolates, while genotype XXVI-Uhrlass was identified in 17 cases. Three previously undescribed ITS genotypes were also recorded. Sequencing of tef1-α and tubb in a subset of isolates showed limited diversity within each ITS genotype, except for genotype III*, which exhibited several sequence variants. Mating-type analysis revealed both idiomorphs in the collection, although a single idiomorph was detected within each ITS genotype except genotype III*. Genotypes III and XXVI exhibited a restricted geographical distribution. Neither T. indotineae, T. mentagrophytes ITS-genotype VII, nor T. interdigitale ITS genotypes were identified. Our results highlight restricted genetic diversity among companion animal-derived isolates in France and support reduced genetic mixing among ITS genotypes, consistent with ongoing speciation processes within T. mentagrophytes species complex.