The Evolving Landscape of Dermatophytosis in the UAE: Trichophyton indotineae and Related Genotypes

Background: Dermatophytosis remains one of the most prevalent superficial fungal infections worldwide, increasingly complicated by the emergence of terbinafine-resistant Trichophyton indotineae. Despite its global spread, molecular and clinical data from the United Arab Emirates (UAE) remain limited. Objectives: We conducted the first comprehensive molecular and phenotypic characterization of dermatophyte infections in the UAE to define the local epidemiology, antifungal resistance patterns and clinical outcomes. Methods: Between September 2024 and March 2025, 33 consecutive clinical dermatophyte isolates associated with tinea infections were collected through passive laboratory-based surveillance across the Abu Dhabi Emirate. Isolates underwent macroscopic and microscopic examination, urease testing, internal transcribed spacer (ITS) genotyping for species identification and sequencing of the squalene epoxidase (SQLE) gene to detect mutations associated with terbinafine resistance. Phylogenetic analyses were conducted using reference ITS genotypes. Antifungal susceptibility testing was conducted on 28 isolates following CLSI M38 guidelines. Results: Among the 33 isolates, 26 (78.8%) were confirmed as T. indotineae, with SQLE mutations detected in 88.5% of isolates, most frequently Phe397Leu and Ala448Thr. Terbinafine demonstrated high non-wild-type rates (63.6%; MIC₅₀/MIC₉₀: 2/> 2 μg/mL), while itraconazole and griseofulvin retained activity. Significant inter-laboratory discordance was observed (6.1% agreement), with conventional methods failing to detect any T. indotineae cases. Most patients (84.8%) reported no travel history, indicating autochthonous transmission. Clinical outcomes were poor despite prolonged combination therapy: only 30.8% achieved improvement while 69.2% experienced recurrence. Conclusions: This study provides baseline evidence of endemic terbinafine-resistant T. indotineae in the UAE, underscoring urgent needs for molecular diagnostics, routine susceptibility testing and antifungal stewardship programs to guide effective management strategies.