Trichophyton rubrum resistant to terbinafine

T. rubrum, a dermatophyte fungus, is the most common cause of dermatophytosis worldwide.¹
Oral terbinafine is considered a first-line treatment for most infections caused by this fungus, but cases of terbinafine-resistant T. rubrum are increasingly being reported worldwide and in the United States, including terbinafine-resistant onychomycosis.^2-4
Researchers have reported cases of difficult-to-treat terbinafine-resistant T. rubrum worldwide, including in the United States.^2,3,5,6
Testing for antimicrobial-resistant T. rubrum is available at select U.S. laboratories.
Patients with terbinafine-resistant Trichophyton rubrum may require treatment with itraconazole or other drugs usually used for treating invasive fungal infections.^2,3

Hay RJ. Superficial Mycoses. In: Ryan ET, Hill DR, Solomon T, Aronson NE, Endy TP, eds. Hunter's Tropical Medicine and Emerging Infectious Diseases. Elsevier; 2020:648-652.
Elewski B. A call for antifungal stewardship. Br J Dermatol. Nov 2020;183(5):798-799. doi:10.1111/bjd.19387.
Gu D, Hatch M, Ghannoum M, Elewski BE. Treatment-resistant dermatophytosis: A representative case highlighting an emerging public health threat. JAAD Case Rep. Nov 2020;6(11):1153-1155. doi:10.1016/j.jdcr.2020.05.025.
Gupta AK, Cooper EA, Wang T, et al. Detection of Squalene Epoxidase Mutations in United States Patients with Onychomycosis: Implications for Management. J Invest Dermatol. Dec 2023;143(12):2476-2483 e7. doi:10.1016/j.jid.2023.04.032.
Gupta AK, Renaud HJ, Quinlan EM, Shear NH, Piguet V. The Growing Problem of Antifungal Resistance in Onychomycosis and Other Superficial Mycoses. Am J Clin Dermatol. Mar 2021;22(2):149-157. doi:10.1007/s40257-020-00580-6.
Hwang JK, Bakotic WL, Gold JA, Magro CM, Lipner SR. Isolation of terbinafine-resistant Trichophyton rubrum from onychomycosis patients who failed treatment at an academic center in New York, United States. Journal of Fungi. 2023;9(7):710.

Recognizing Trichophyton indotineae

Access Academy guidance on recognizing signs of infection by T. indotineae.

See Academy information on prevention and treatment of T. indotineae.

Trichophyton mentagrophytes type VII

See Academy guidance on T. mentagrophytes type VII and other emerging dermatophytes.

Emerging diseases registry

Report suspected cases of antifungal-resistant dermatophytosis, mpox, and COVID-19.