Towards an Early Clinical and Biological Resistance Detection in Dermatophytosis: About 2 Cases of Trichophyton indotineae.

Trichophyton indotineae causes resistant dermatophytosis to terbinafine. The global spread of terbinafine-resistant Trichophyton indotineae strains with mutations in the squalene epoxidase gene is a major issue. This emerging species is now more frequently isolated in Europe and we report here two cases of T. indotineae tinea corporis in Switzerland, one with in vitro resistance to terbinafine and a second with in vitro susceptibility but a clinical resistance. Mycology isolation from cultures and sequencing ITS gene were used to confirm T. indotineae infection. In vitro antifungal susceptibility was tested in a microplate with a colorimetric detection of fungal viability for the determination of the minimal inhibitory concentration (MIC). Facing these emerging resistances and since there are a limited number of antifungal agents available to treat dermatophytosis, the early detection of terbinafine resistance should be a prerequisite in the management of T. indotineae infections.