Global Emergence of Trichophyton mentagrophytes ITS Genotype VIII (Trichophyton indotineae): A Scoping Review of Epidemiology, Clinical Features, and Antifungal Resistance, 2019–2025

Aditya K Gupta,1,2 Amanda Liddy,2 Tong Wang,2 Baruch Kaplan,3 Avner Shemer,4,5 Mesbah Talukder2,6 1Department of Medicine, Division of Dermatology, University of Toronto, Toronto, ON, Canada; 2Mediprobe Research Inc., London, ON, Canada; 3Adelson School of Medicine, Ariel University, Ariel, Israel; 4Department of Dermatology, Sheba Medical Center, Ramat-Gan, Israel; 5Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; 6School of Pharmacy, BRAC University, Dhaka, BangladeshCorrespondence: Aditya K Gupta, Mediprobe Research Inc., 645 Windermere Road, London, ON, N5X 2P1, Canada, Tel +1-519-851-9715, Fax +1-519-657-4233, Email [email protected]; [email protected]: Over the past decade, reports of difficult-to-treat, antifungal-resistant superficial fungal infections have increased markedly, raising global concern among clinicians and public health authorities. Trichophyton mentagrophytes ITS genotype VIII, more recently classified as T. indotineae, has emerged as a principal driver of this shift, with infections often presenting as inflammatory, extensive dermatophytoses that are prone to persistence and relapse despite antifungal therapy. This scoping review synthesizes literature published between 2019 and 2025 to provide a comprehensive overview of emerging trends in epidemiology, clinical features, antifungal susceptibility, molecular resistance mechanisms, and management strategies. Resistance in T. indotineae contributes not only to prolonged disease courses and recurrent infections but also to intrafamilial and community outbreaks, highlighting the species’ capacity for rapid and widespread transmission. These challenges are compounded by diagnostic limitations, variable correlation between squalene epoxidase gene mutations and terbinafine susceptibility, and the continued reliance on terbinafine as a first-line systemic therapy in many regions. Together, these factors underscore the urgent need for integrated diagnostic and management approaches, combining phenotypic susceptibility testing, genotypic analysis, and careful clinical assessment. Moreover, updated treatment guidelines and coordinated public health interventions are critical to mitigate transmission, optimize therapeutic outcomes, and address the growing clinical and epidemiological burden posed by resistant T. indotineae infections worldwide.Keywords: dermatomycoses, Trichophyton indotineae, Trichophyton mentagrophytes ITS genotype VIII, tinea, antifungal drug resistance, terbinafine, itraconazole