An Emerging Fungal Pathogen: Trichophyton Indotineae
DOI:
https://doi.org/10.58931/cdt.2025.64152Abstract
Dermatophytoses are common fungal infections of the skin and other keratinized structures such as hair and nails. These infections, caused by the dermatophyte fungi, affect approximately 25% of people worldwide. Dermatophyte fungi include species from three genera: Trichophyton, Epidermophyton, and Microsporum, and may be categorized as anthropophilic, zoophilic, or geophilic. Most cases of dermatophytosis in Canada are attributable to T. rubrum.
Over the past decade, there have been an increasing number of reports of terbinafine‑resistant dermatophyte infections. Most of these cases are attributable to Trichophyton indotineae, a newly described pathogen. Initially described in South and South‑East Asia, T. indotineae has quickly become a worldwide health concern, with isolates detected in more than 40 countries. Epidemiological data reviews have revealed that T. indotineae had been circulating in Oman, Iran, India, and Australia as early as 2004, with an increasing number of cases occurring after 2014 due to an outbreak in India.
Recent reports suggest that most new dermatophyte infections in India are attributable to this new pathogen. The development of terbinafine resistance has been attributed to overuse of topical medications containing fixed‑dosed combinations of corticosteroids and antifungal agents, which are widely available over-the-counter in parts of Asia and Africa. This highly virulent, treatment-resistant fungus may present with chronic, extensive disease and atypical presentations, resulting in significant difficulties for both diagnosis and treatment.
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