Detection of Pan-Dermatophytes and Trichophyton rubrum Using Recombinase Polymerase Amplification-Lateral Flow Dipstick Assay

BackgroundTraditional methods for diagnosing onychomycosis are characterized by limited sensitivity and prolonged processing times, and heavily rely on the skill level of laboratory personnel.ObjectivesTo develop a fast, simple, user-friendly, and reliable molecular assay that offers high sensitivity and specificity for the detection of common dermatophytes in nail specimens.MethodsWe developed a technique that integrates recombinase polymerase isothermal amplification with lateral flow dipstick (RPA-LFD) for the detection of pan-dermatophytes and Trichophyton rubrum, and evaluated its analytical sensitivity and specificity. This method was applied to analyze 190 nail specimens, with the results compared with traditional microscopy and fungal culture.ResultsThe RPA-LFD assay demonstrated an analytical sensitivity of 10 pg/reaction for pan-dermatophytes and 1 pg/reaction for T. rubrum. In clinical evaluations for tinea unguium, the sensitivity of the RPA-LFD, fungal culture, and microscopy methods, as determined through latent class analysis, was estimated to be 91.0%, 70.8%, and 93.9%, respectively. Correspondingly, the specificity of these methods-RPA-LFD, fungal culture, and microscopy-was assessed at approximately 95.7%, 98.0%, and 94.3%.ConclusionsOur RPA-LFD assay exhibited high sensitivity and specificity in the detection of dermatophytes. Due to its technical simplicity, enhanced sensitivity, and reduced processing times, it represents a promising alternative to conventional fungal culture methods for the mycological detection and identification of dermatophytes.