Trichophyton indotineae: Rise, Diagnosis, Treatment, and Future Directions.

Dermatophytoses (synonymous with tinea) are superficial fungal infections of the skin, hair, and nails, typically caused by dermatophytes in the genera of Trichophyton and Microsporum. Dermatophyte infections are common and are estimated to affect roughly 20-25% of the global population. Historically, tinea infections have been treated with short courses of topical and/or oral antifungal therapies, however, the last decade has seen increasing antifungal treatment failure. Trichophyton (T.) indotineae (previously termed Trichophyton mentagrophytes-genotype VIII) has emerged as the primary species driving antifungal treatment failure worldwide. Clinically, T. indotineae infection may present as a typical dermatophyte infection, or atypically may mimic eczema, psoriasis, or other inflammatory dermatoses. Patients are often strikingly itchy and may be using topical steroid creams inappropriately in combination with antifungal and antibiotic agents. Terbinafine, once considered a first-line oral agent for tinea infections, often fails against T. indotineae, for which prolonged courses of itraconazole (often at higher than typical dermatophyte dosing) are now regarded as the treatment of choice. Fluconazole and griseofulvin demonstrate limited efficacy. Antifungal susceptibility testing may guide treatment choices but is not well established for dermatophytoses. Dermatologists should be aware of an approach to evaluating and treating refractory dermatophyte infections. Increased awareness among clinicians, including in infectious diseases, primary care, and the emergency room, is also important to facilitate early recognition, appropriate management, and timely referral. Dermatologists may play a key role in promoting antifungal stewardship and educating other clinician groups about emerging dermatophyte infections. In this review, we detail T. indotineae with a focus on clinical presentation, diagnostic confirmation, and treatment.