Concerning rates of laboratory‐confirmed antifungal‐resistant onychomycosis and tinea pedis: An online survey of podiatrists, United States

1 Antifungal-resistant tinea is an emerging global public health problem. 2 A recent, large analysis of toenail samples from US patients with suspected onychomycosis found that nearly 4% of Trichophyton spp samples had squalene epoxidase gene mutations, which are associated with terbinafine resistance. 3 Clinicians may be increasingly likely to encounter resistant tinea infections. [...]we aimed to assess diagnostic approaches, antifungal resistance testing practices, and treatment practices for treatment-resistant onychomycosis and tinea pedis. Characteristic n = 297 % How do you (or would you) define treatment failure for dermatophyte (tinea) infections? a Failure of normal course of terbinafine (Lamisil) 215 72.4 Failure of multiple topical therapies 212 71.4 Infection that spreads during treatment 143 48.1 Failure of multiple oral therapies 135 45.5 Multiple specialists involved, employing multiple agents with little or no disease resolution 133 44.8 Other (specify) 14 4.7 Type of diagnostic testing ordered for dermatophyte infections a,b PAS histological examination 211 81.5 DNA-based molecular testing (e.g., PCR) 154 59.5 Microscopic KOH examination 110 42.5 Microscopic culture for fungal identification only 91 35.1 Susceptibility testing 56 21.6 Other 9 3.5 Logistical barriers to diagnostic testing a High cost of diagnostic testing 177 59.6 No logistical barriers 83 27.9 Long turnaround time 49 16.5 Difficulty accessing the testing 37 12.5 Other 29 9.8 Difficulty interpreting MIC values 13 4.4 Has the laboratory reported back to you antifungal resistance for any of your treatment failure cases? a No 208 70.0 Yes 89 30.0 Yes, but treatment failure might be due to other factors (e.g., patient non-adherence) 51 17.2 Yes, and there appears to be a correlation between treatment failure and terbinafine resistance 49 16.5 Yes, and there appears to be a correlation between treatment failure and topical antifungal resistance 31 10.4 Yes, and there appears to be a correlation between treatment failure and itraconazole resistance 10 3.4 Yes, and there appears to be a correlation between treatment failure and fluconazole resistance 8 2.7 Abbreviations: KOH, potassium hydroxide; MIC, minimum inhibitory concentration; PAS, Periodic acid–Schiff. a “Check all that apply” format; totals can exceed 100%; b Excluding n = 38 (12.8%) respondents who said “I am not testing.” [...]our study highlights the burden of onychomycosis, as suggested by the high percentage of ony