Abstract Background: Trichophyton indotineae is an emerging fungal strain causing extensive treatment-resistant dermatophytosis. Recently, Singapore reported its first case of T. indotineae dermatophytosis. Materials and Methods: A retrospective review of 37 patients with culture-positive T. indotineae between January 2024 and March 2025 was conducted at the National Skin Centre, Singapore. Results: Thirty-seven patients were included, with a median age of 41.0 (interquartile range IQR 28–50 years). Most were not immunocompromised. Eleven reported close contacts with family members or colleagues with tinea, and eight had significant travel history to countries in South Asia or Southeast Asia. Thirty-five patients were treated with oral antifungals. Of these, 9 patients achieved clearance with no relapses and 23 improved but experienced frequent relapses after treatment discontinuation, which required ongoing treatment. Terbinafine (250 mg daily) and oral itraconazole (100 mg twice daily) were the most common regimens, and the median oral antifungal treatment duration was 6.5 (IQR 3.5–11) weeks. Differences in morphology (presence of intercalary chlamydospores), pigmentation on reverse culture and phenotype were used to differentiate T. indotineae from other species. Discussion and Conclusions: This is the largest reported cohort of T. indotineae infection in Singapore, highlighting the increased resistance to oral antifungals. While internal transcribed spacer sequencing remains the gold standard of diagnosis, we propose using culture morphology features for identification when the former is unavailable. Extended courses of oral antifungals should be considered for T. indotineae dermatophytosis to prevent relapse and achieve clearance.
Tow et al. (Thu,) studied this question.