Comment on: Multicentre validation of a EUCAST method for the antifungal susceptibility testing of microconidia-forming dermatophytes

Abstract

In 2020, we published a multicentre study validating a new EUCAST method for the antifungal susceptibility testing of microconidia-forming dermatophytes.1 We included molecularly confirmed terbinafine-resistant and -susceptible Trichophyton rubrum and Trichophyton interdigitale isolates and established wild-type upper MIC limits (WT-UL) for both species. Since then, the taxonomy for the Trichophyton mentagrophytes/T. interdigitale complex has been revised and a new species Trichophyton indotineae proposed for the highly terbinafine-resistant Indian isolates.2,3 These species cannot be distinguished by phenotypic tests although T. indotineae isolates are most often lighter in colour and less often positive in Tween-80 opacity, urea hydrolysis and hair perforation tests than T. mentagrophytes and T. interdigitale.3 Consequently, T. indotineae has been reported in the literature under all three species names and susceptibility data reported for the species complex cannot be reliably linked to the individual species unless identification to the sensu stricto level has...