Trichophyton indotineae: A Comprehensive Review of an Emerging Antifungal-resistant Dermatophyte

Trichophyton indotineae has emerged as an important global health threat, causing widespread, chronic, and recalcitrant dermatophytoses.This review synthesizes the current understanding of this pathogen, which was phylogenetically reclassified from Trichophyton mentagrophytes internal transcribed spacer (ITS) genotype VIII.Originating from the Indian subcontinent, T. indotineae has spread across Asia, Europe, and North America, with international travel being a significant factor in its dissemination.Its rise is alarming due to high rates of resistance to terbinafine, a primary oral antifungal, driven by specific point mutations in the squalene epoxidase (SQLE) gene.Furthermore, emerging decreased susceptibility and resistance to azole antifungals, linked to alterations such as CYP51B gene duplication, raise serious concerns about multidrug-resistant (MDR) strains.Clinically, T. indotineae typically presents as extensive and inflammatory tinea corporis and tinea cruris, where diagnostic delays and inappropriate steroid use can worsen severity.Accurate identification is critical but cannot be achieved by conventional mycological methods, necessitating molecular techniques such as ITS sequencing as the gold standard.Treatment is challenging; terbinafine frequently fails, making itraconazole and voriconazole the main therapeutic alternatives, often requiring higher doses and prolonged courses.The ineffectiveness of older agents such as fluconazole and griseofulvin further limits options.The global spread of this resistant dermatophyte underscores the urgent need for a multifaceted public health response, including enhanced molecular surveillance, robust antifungal stewardship programs, increased laboratory capacity for diagnostics and susceptibility testing, and greater awareness among clinicians and the public to curb its transmission and impact.