Clinical alert: arrival of terbinafine resistant Trichophyton indotineae in New Zealand.

Background: Over the past decade there has been a rapid emergence of a new dermatophyte species Trichophyton indotineae (T. indotineae) in the Indian subcontinent, with associated global spread. It is noted for extensive recalcitrant infections and high rates of terbinafine resistance that are changing treatment paradigms for tinea infection.

Aim: To report on the epidemiology of dermatophyte infections from the National Mycology Reference Laboratory at Auckland City Hospital and the arrival of T. indotineae in New Zealand.

Methods: This was a retrospective review of laboratory data from January 2017 to August 2024. Antifungal susceptibility was performed by disc testing. Species identification was performed by phenotypic methods and for a limited number of isolates by DNA sequence analysis.

Results: There were 961 dermatophytes identified. Trichophyton rubrum was the most common species, accounting for 72% of all isolates. There were 85 (9%) confirmed or probable T. indotineae identified from 63 individuals. These included both Auckland isolates and isolates referred from laboratories around the country. Of the 49 T. indotineae isolates that had antifungal susceptibility testing performed, only 30 (61%) were susceptible to terbinafine, while 45 (92%) were susceptible to itraconazole.

Conclusions: Terbinafine resistant T. indotineae has arrived in New Zealand. To assist appropriate management, practitioners encountering extensive tinea infection, particularly if failing terbinafine treatment, should request culture, asking for full dermatophyte identification and susceptibility testing. Itraconazole is the recommended treatment for T. indotineae, and up to 12 weeks duration may be required.