Eight-year molecular epidemiology of dermatophytosis in the Czech Republic and antifungal susceptibility patterns of selected species
A large-scale molecular epidemiology project has been conducted by a collaborative network of 8 institutions in the Czech Republic. Isolates and associated data obtained between 2012 and 2019 were analysed. Huge collection comprising almost nine thousands of isolates has been collected and identified using ITS rDNA sequencing (with exception of morphologically typical Trichophyton rubrum strains). In total, 30 dermatophyte species were identified, including several hitherto undescribed species. In the Czech Republic, the most common clinical entity is the onychomycosis that is predominantly caused by T. rubrum and T. interdigitale (together almost 99% of all cases). Tinea pedis has similar etiology. Tinea corporis is mostly caused by anthropophilic species (~54%), especially by T. rubrum (~51%), and zoophilic species (~42%), especially by T. benhamiae complex members (~24%), M. canis (~10%) and T. interdigitale-mentagrophytes (~8%). Remaining 4% of tinea corporis cases are caused by species-rich geophilic dermatophytes. Tinea capitis is relatively uncommon clinical unit in the Czech Republic that is predominantly of zoonotic origin (M. canis and T. benhamiae complex species cause >70% of cases).
In 2019, we established standardized antifungal susceptibility testing methods for filamentous fungi (EUCAST-AFST methodology), including dermatophytes, that has not been available in the Czech Republic. Antifungal susceptibilities to the eight antifungals (fluconazole, terbinafine, itraconazole, ketoconazole, clotrimazole, amorolfine, ciclopirox olamine and efinaconazole) were determined in sixty-nine isolates of zoophilic T. benhamiae complex species. Similar approach was used in 70 geophilic Arthroderma species occurring in the clinical samples. This set comprised nine different species (e.g. A. quadrifidum, A. insingulare, A. onychocola). Considering increasing incidence of terbinafine-resistant T. interdigitale and T. rubrum strains worldwide, we have started to screen for terbinafine resistance in these species since January 2020 and preliminary data are presented. The large collection of dermatophyte isolates and available genomic DNAs offer great potential for future epidemiological, population genetic and taxonomic investigations, and also collaboration with other laboratories worldwide.