Treatment and diagnostic challenges associated with the novel and rapidly emerging antifungal-resistant dermatophyte, Trichophyton indotineae.

Abstract

Trichophyton indotineae is a recently discovered dermatophyte species that causes recalcitrant dermatophytosis. It was first reported from India and has quickly spread across the globe. The exact prevalence of T. indotineae remains unknown due to limited surveillance. It has reached epidemic proportions in the Indian subcontinent. In India, this new species has largely replaced other previously common dermatophytes. Reports from Western countries suggest most cases are imported, with some reports of local transmission. A recent report from the United Kingdom indicates that T. indotineae now accounts for 38% of dermatophyte isolates tested in their national referral laboratory. T. indotineae causes widespread, inflammatory dermatophytosis affecting large areas of the body. Dermatophytosis caused by T. indotineae is difficult to manage due to the limited availability of mycology laboratories capable of reliably identifying and performing antifungal susceptibility testing, and because of its resistance to commonly used antifungals. Culture and physiological characteristics cannot confirm identification to the species level, requiring species-level confirmation by molecular methods like internal transcribed spacer sequencing. It is important for clinicians and mycology laboratories to be aware of and consider the possibility of T. indotineae infection in patients with relevant demographic, clinical, and travel history. This would decrease delay in diagnosis, prevent inappropriate use of medications like steroids and ineffective antifungal agents, and provide opportunities to make recommendations for good hygiene practices to prevent transmission. In this mini review, we describe the emergence of T. indotineae, its diagnostic and treatment challenges, and the current state, and provide recommendations for future direction.