Confirmation of dermatophytes in nail specimens using in-office dermatophyte test medium cultures. Insights from a multispecialty survey.

Using data from a multicenter nationwide multispecialty survey, the authors investigated the efficacy of in-office dermatophyte test medium (DTM) and central laboratory cultures used to confirm onychomycosis across samples collected by podiatric, dermatologic, and primary-care physicians. The samples collected by podiatric physicians were both positive or both negative in 43% and 27% of patients, respectively. Samples harvested by dermatologists were both positive in 37% of patients and both negative in 32%, while the samples collected by primary-care physicians were both positive in 28% of patients and both negative in 38%. The accuracy of DTM and central laboratory tests is dependent on the proper collection of nail samples, and the accuracy of mycologic test results varied significantly across nail specimens harvested by podiatric, dermatologic, and primary-care physicians. DTM culture was found to be an effective and convenient method of confirming dermatophyte infections in patients with signs of onychomycosis. The data presented here indicate that the special expertise of podiatric physicians in treating foot-related illnesses translates into more accurate mycologic testing.