The following is a summary of “Detection of Squalene Epoxidase Mutations in United States Patients with Onychomycosis: Implications for Management,” published in the November 2023 issue of Dermatology by Gupta, et al.
More and more people are reporting that oral terbinafine, the most popular fungicide used to treat dermatophytosis and onychomycosis worldwide, is not working as well as it used to. For a study, researchers sought to find out how common squalene epoxidase mutations are and how widespread the species are among toenail dermatophyte isolates. Samples from 15,683 people in the US who saw doctors and podiatrists and were thought to have onychomycosis were studied.
They looked at clinical data and used multiplex real-time PCRs to find dermatophyte species with or without squalene epoxidase mutations. Dermatophytes were found 37.6% of the time; 88.3% of the isolates from the Trichophyton genus were from the T. rubrum complex, and 11.2% were from the T. mentagrophytes complex. The T. mentagrophytes complex infected people over 70 more often than younger people. The average rate of mutation in Trichophyton species was 3.7%. The T. mentagrophytes complex had a higher mutation rate (4.3%) than the other species (3.6%).
Mutations that were found most often were T1189C/Phe397Leu (34.5%), T1306C/Phe415Ser (16.0%), and C1191A/Phe397Leu (11.0%). People in the United States who have toenail onychomycosis have been found to have squalene epoxidase gene changes that make them less sensitive to terbinafine. Doctors should know what makes people more likely to become resistant to antifungals and use antifungal management techniques like guided evaluation and treatment of onychomycosis and dermatophytosis.
Source: sciencedirect.com/science/article/abs/pii/S0022202X23021231