Retrospective molecular characterization of <i>Trichophyton</i> isolates from animals in Spain

Some species of the genus Trichophyton are among the most important causes of dermatophytosis worldwide, one of the most common mycoses which affect both humans and animals. The phylogeny of dermatophytes has shifted greatly in the past two decades with the introduction of molecular techniques. This work is a retrospective genetic analysis of 91 Trichophyton isolates obtained mainly from animals attending the Veterinary Hospital of the Universitat Autònoma de Barcelona between 1984 and 2025. The isolates were identified using conventional mycological methods and subsequently confirmed by Sanger sequencing of the rDNA Internal Transcribed Spacer (ITS) region. The species were identified as Trichophyton mentagrophytes (61.5%), Trichophyton erinacei (16.5%), Trichophytoneuropaeum (7.7%), Trichophyton equinum (5.5%), Trichophyton japonicum (4.4%), Trichophyton benhamiae (2.2%), and Trichophyton verrucosum (2.2%). Additionally, T. mentagrophytes isolates were grouped into different genotypes. Our study showed that isolates recovered from chinchillas and rabbits were identified as T. mentagrophytes genotypes III* and XXIV whereas isolates from hedgehogs were identified as T. erinacei. In guinea pigs, T. europaeum was the most common species. Most isolates recovered from dogs belonged to T. mentagrophytes genotypes II* and III*, although T. japonicum and T. europaeum were also recovered. In horses, isolates were identified as T. equinum and T. mentagrophytes genotype III*. Cow isolates were identified as T. verrucosum whereas those from goat and sheep were identified as T. mentagrophytes genotype V. Trichophyton indotinae (T. mentagrophytes genotype VIII) was not found. This long-term dataset illustrates the stability and diversity of animal association Trichophyton species over the time.