Trichophyton indotineae: Epidemiology, antifungal resistance and antifungal stewardship strategies

There has been a recent shift in the epidemiology of superficial fungal infections (tinea, dermatophytosis, dermatomycoses). Trichophyton indotineae is an emerging dermatophyte species of significant global concern for its contagious nature and antifungal drug resistance. This scoping review includes available clinical and laboratory assessments of T. indotineae to provide a comprehensive up-to-date overview of its epidemiology, clinical manifestations, diagnostic approaches, antifungal susceptibility patterns, resistance mechanisms and management strategies. We discuss T. indotineae resistance against standard and newer antifungals (terbinafine, griseofulvin and triazoles including fluconazole, itraconazole, voriconazole and posaconazole). In particular, the terbinafine susceptibility profile of T. indotineae can be linked to squalene epoxidase (SQLE) single-nucleotide variations. For diagnosis, it is not possible to separate T. indotineae from other members of the T. mentagrophytes complex (T. mentagrophytes and T. interdigitale) without access to molecular diagnostic methods. So, in patients presenting with extensive dermatophytoses, with a history of treatment resistance and/or recent travel, molecular diagnosis to confirm T. indotineae infection should be considered. Healthcare providers often face challenges in choosing between terbinafine and itraconazole treatments. While the use of terbinafine is limited due to resistance, itraconazole is hindered by erratic absorption, possible drug interactions and side effects as well as resistance in some cases. Newer treatments being investigated include super-bioavailable itraconazole, third-generation triazoles (voriconazole, posaconazole) and topical-oral combination regimens. The need for improved diagnostic accessibility, judicious antifungal prescribing, and implementing an effective antifungal stewardship program are highlighted.