Trichophyton indotineae: An Emerging Fungal Pathogen with High Terbinafine Resistance

Trichophyton indotineae, formerly known as Trichophyton mentagrophytes genotype VIII, is a recently emerged and highly contagious dermatophyte species that causes chronic or recurrent superficial infections of the skin, hair, and nails. Trichophyton indotineae infections are highly transmissible and characterized by inflammatory, pruritic, and extensive lesions on the body and difficult to treat. It is worth noting that the most strains of T. indotineae have high resistance to terbinafine which is attributed to single-point mutation alterations in the squalene epoxidase gene. Instances of T. indotineae infections have been reported in various geographical regions across the world. The identification of species and the determination of antifungal susceptibility tests are essential components of infection control, yet these diagnostic methods are still problematic. In chronic dermatophytosis caused by T. indotineae, systemic treatment is usually required, and itraconazole is often prescribed in case of resistance to terbinafine. The use of relatively new antifungal agents, such as voriconazole and luliconazole, as well as combination therapy, could be used for T. indotineae infections. This comprehensive review attempts to provide an overview of T. indotineae, including its global distribution, taxonomy, clinical manifestations, antifungal resistance mechanisms, therapeutic interventions, and diagnosis complications. By shedding light on the characteristics of this emerging fungus, the present review contributes to a broader understanding of T. indotineae infection and the development of more effective management strategies.