RESUMEN
Dermatophytes are a group of eukaryotic microorganisms characterized by high capacity to colonize keratinized structures such as the skin, hair, and nails. Over the past years, the incidence of infections caused by zoophilic species, e.g., Trichophyton verrucosum, has been increasing in some parts of the world, especially in Europe. Moreover, the emergence of recalcitrant dermatophytoses and in vitro resistant dermatophytes has become a cause of concern worldwide. Here, we analyzed the mechanisms underlying resistance to fluconazole among clinical isolates of T. verrucosum. Quantitative RT-PCR was carried out to determine the relative expression levels of mRNA transcripts of ERG3, ERG6, and ERG11 genes in the fungal samples using the housekeeping gene GAPDH as a reference. Our results showed that the upregulation of the ERG gene expression is a possible mechanism of resistance to fluconazole in this species. Furthermore, ERG11 is the most statistically significantly overexpressed gene in the pool of fluconazole-resistant T. verrucosum isolates. Additionally, we have demonstrated that exposure to fluconazole increases the levels of expression of ERG genes in fluconazole-resistant isolates of T. verrucosum. In conclusion, this study has shown one of the possible mechanisms of resistance to fluconazole among zoophilic dermatophytes, which involves the maintenance of high levels of expression of ERG genes after drug exposure.
Asunto(s)
Arthrodermataceae , Farmacorresistencia Fúngica , Fluconazol , Proteínas Fúngicas , Regulador Transcripcional ERG/genética , Animales , Antifúngicos/farmacología , Arthrodermataceae/efectos de los fármacos , Arthrodermataceae/genética , Farmacorresistencia Fúngica/genética , Fluconazol/farmacología , Proteínas Fúngicas/genética , Regulación Fúngica de la Expresión Génica , Humanos , Trichophyton/efectos de los fármacos , Trichophyton/genéticaRESUMEN
Each year, millions of people worldwide are affected by superficial mycoses, which are frequently caused by dermatophytes having affinity to the scalp, nails, hair and the stratum corneum of the skin. The changing reservoirs of zoophilic dermatophytes, the numerous reports of animal carrier status, and the increasing number of pets make the diagnosis difficult, which is usually impossible based only on medical history. Herein we present a case report of tinea corporis caused by Trichophyton equinum in siblings who had no contact with horses. The routine laboratory diagnostic procedures for identification of isolates were based on phenotypic and genotypic characteristics, especially molecular techniques using rDNA internal transcribed spacer sequences. The results showed that both techniques proved to be insufficiently discriminatory to differentiate two closely related species, i.e. Trichophyton equinum and Trichophyton tonsurans. Introduction of a TEF1 sequence analysis to the diagnostic procedures revealed consistent differences between these two species and facilitated unambiguous identification. Interestingly, dogs that could leave the homestead freely were the source of the infection in children. In conclusion, Trichophyton equinum was considered in the past as a strict zoophilic dermatophyte associated with horses and rarely transmitted to humans. This study revealed that this species can have other reservoirs and live in the fur of asymptomatic animals.