Assessment of the PreventID Dermatophyte immunochromatographic test for diagnosing onychomycosis: Integration into routine clinical practice in a tertiary care hospital.

Onychomycosis is a common nail infection predominantly caused by dermatophytes. Accurate diagnosis is essential to guide antifungal therapy, yet conventional methods such as direct examination (DE) and fungal culture have important limitations, including operator dependence and long turnaround times. Rapid antigen-based assays, such as immunochromatographic tests (ICTs), have emerged as potential alternatives, but their performance under routine laboratory conditions remains insufficiently defined. To evaluate the diagnostic performance of the PreventID Dermatophyte immunochromatographic test under controlled conditions and during routine clinical implementation, using fungal culture as the reference standard. This study was conducted in two phases at a tertiary care hospital. During the pilot phase (November 2023-February 2024), nail samples from patients with suspected onychomycosis were analyzed in parallel using ICT, DE, and fungal culture. During the implementation phase (September 2024-September 2025), ICT was introduced as a first-line screening tool. A subset of samples processed in October 2024 and January 2025 underwent parallel testing with ICT, DE, and culture for direct comparison. Diagnostic performance metrics were calculated using dermatophyte culture as the reference standard. In the pilot phase, 49 samples were analyzed, with dermatophytes isolated in 18 cases. ICT showed a sensitivity of 88.9%, specificity of 90.3%, and substantial agreement with culture (κ = 0.78), outperforming DE in sensitivity. During routine implementation, 904 ICTs were performed; among ICT-negative samples undergoing culture, dermatophytes were isolated in 52 cases, yielding a negative predictive value of 87.5%. During the systematic comparison period, ICT sensitivity decreased to 37.5% with poor agreement (κ = 0.08), whereas DE showed higher sensitivity (63.9%) and moderate agreement (κ = 0.53). PreventID Dermatophyte performs well under controlled conditions but shows reduced sensitivity in routine practice. Although its rapid turnaround makes it a useful screening tool, the observed false-negative rate limits its reliability as a stand-alone test to exclude infection. Therefore, ICT results should be interpreted in conjunction with clinical findings and confirmed by conventional methods, supporting its role within a multimodal diagnostic strategy.