Evaluation of COPAN FecalSwab and eSwab collection systems for the detection of Clostridioides difficile using the BD...

Clostridioides difficile infection (CDI) requires accurate and timely diagnostic testing to guide treatment. Nucleic acid amplification tests (NAATs) offer high sensitivity and specificity, but most assays, including the Health Canada-approved BD MAX Cdiff assay, are validated only for unpreserved stool. This presents challenges for transport, stability, and specimen sharing between tests. Swab-based collection systems such as COPAN FecalSwab and eSwab may alleviate these limitations but have not been fully evaluated on the BD MAX Cdiff assay. Residual stool specimens submitted for CDI testing were used to prepare FecalSwab and eSwab aliquots and evaluated to determine the optimal volume for BD MAX Cdiff testing. Sensitivity, specificity, and agreement were calculated using unpreserved stool as the reference method. Stability of C. difficile DNA was assessed at 4°C, room temperature, and 37°C over 14 days. Minimal variation in C. difficile PCR cycle threshold (Ct) values was observed across varying volumes of FecalSwab and eSwab media, and 100 µL was selected. C. difficile DNA was detected in all specimen types up to 14 days at different temperatures. However, a gradual increase in Ct values was noted over time for all specimens and storage temperatures, except for FecalSwab specimens stored at 4°C. FecalSwab specimens demonstrated 98.5% sensitivity and 98.4% specificity, while eSwab specimens demonstrated 97.6% sensitivity and 100% specificity against unpreserved stool. Agreement between the two swab types was 98.4%. FecalSwab and eSwab specimens prepared from unpreserved stool demonstrate excellent agreement with unpreserved stool, and provide improved options for specimen transport and stability.IMPORTANCEThis study demonstrates the utility of FecalSwab and eSwab collection media on the BD Max Cdiff assay. This addresses an important gap in the diagnosis of Clostridioides difficile infection by evaluating other specimen types beyond neat stool specimens. We demonstrate that swabs collected from stool into FecalSwab and eSwab media have excellent sensitivity and specificity compared to neat stool. Further, FecalSwab and eSwab media allow for preservation of C. difficile DNA at varying storage conditions. This could alleviate specimen transport challenges in remote or resource-limited settings.