Epidemiology and Genomic Characterization of Trichophyton mentagrophytes over a Period of 4 Years in Northern Italy

Dermatophytes are keratinophilic fungi that cause a wide range of superficial infections in humans and animals. The Trichophyton mentagrophytes species complex is one of the most clinically important groups due to its broad host range, widespread distribution, and increasing involvement in antifungal-resistant infections. Here, we described the epidemiology of T. mentagrophytes over a period of 4 years detected in the northeastern part of Italy and provided the genomic characterization of clinical isolates. ITS sequence analysis revealed that among the 13 strains studied, 11 belonged to the T. mentagrophytes complex. In detail, nine were classified as genotype I/II and two as genotype VII. Analysis of the SQLE gene revealed that nine strains harbored a wild-type gene, while two carried a Lys276Asn mutation. Genomic analysis was performed on three clinical T. mentagrophytes strains that belonged to genotype I/II, revealing the presence of different virulence factors including MEP-1, MEP-2, MEP-3, and MEP-5. Phylogenetic analysis based on core-genome SNPs demonstrated that the two genomes included in this study were clonally related to a T. mentagrophytes strain isolated in China in 2024. In conclusion, our study highlights the importance of genomic characterization in order to trace the epidemiology of dermatophytes worldwide and to characterize emerging strains.