Dermatophyte Resistance to Antifungal Drugs: Current Situation and Mechanisms

Abstract

　With the emergence of antimicrobial resistance as one of the leading public health threats of the 21st century, antifungal drug resistance in dermatophytes is also becoming a real problem in dermatology. In 2017, our Japan/Switzerland collaborative research team found 17 dermatophyte strains showing reduced susceptibility to terbinafine, one of the major antifungal drugs for superficial mycoses among just over 2,000 clinical Trichophyton rubrum and Trichophyton interdigitale isolates in Switzerland. Since then, increasing numbers of dermatophyte clinical isolates resistant to this drug have been documented. More recently, dermatophyte clinical isolates with reduced susceptibility to azole compounds, a widely used class of antifungal medications, have been isolated. Furthermore, we recently found a new mechanism of azole resistance involving the overexpression of CYP51B resulting from additional copies of this gene in Trichophyton indotineae, a new dermatophyte species independent of T. interdigitale. This paper reviews the current status of our understanding of the epidemiology and mechanisms of antifungal drug resistance in dermatophytes.