Isolation of Terbinafine-Resistant Trichophyton rubrum from Onychomycosis Patients Who Failed Treatment at an Academic Center in New York, United States

Onychomycosis is a common nail infection. Terbinafine-resistant dermatophyte infections pose an emerging global public health concern, but few cases have been described in the United States. We retrospectively reviewed and characterized clinical, histopathological, mycological features of patients with mycologically confirmed onychomycosis who failed oral terbinafine treatment for at U.S. academic referral center ascertained terbinafine-resistant isolates. During 1 June 2022–31 January 2023 Weill Cornell Medicine New York City, USA, 96 were treated terbinafine. Among 64 adequate follow-up, 36 had clinical or complete cure. Of 28 treatment, 17 underwent resistance testing. Trichophyton rubrum resistance-conferring mutations was isolated from two patients. Overall, failures relatively common, some associated T. infections. These findings underscore need awareness this problem efforts to monitor prevent spread. highlight importance diagnostic testing species identification increasingly important role fungal susceptibility guide therapy.