Optimized Surveillance Testing for Toxigenic Clostridioides difficile to Scale Prevention Programs Across Clinical...

Clostridioides difficile is the leading cause of healthcare acquired infections (HAIs). Healthcare systems lack scalable strategies to identify patients colonized with toxigenic strains to inform prevention programs. We developed a scalable program using rectal swabs, collected for vancomycin resistance Enterococci surveillance, with ex vivo amplification of C. difficile in Cdiff Banana Broth (BB). Optimized confirmatory testing of BB-positive tubes used the rapid C. difficile QuickCheck assay with Cepheid's Xpert^® C. difficile/Epi (Xpert) to confirm toxin gene carriage for QuickCheck results of C. difficile glutamate dehydrogenase-positive (GDH) and antigenic toxin-negative. BB with confirmation demonstrated 92% specificity and 100% sensitivity, to a limit of <5 colony forming units (CFU)/swab, versus published values of 100/swab by ChromID^® C. difficile agar and 460/swab by direct Xpert swab testing. The two-step confirmation detected toxigenic C. difficile in cases missed by other methods. Prospective testing of 797 VRE swabs from 538 ICU and inpatient oncology patients seen at an academic medical center and two community hospitals demonstrated 11% positivity for toxigenic and 4% for non-toxigenic C. difficile. Among swabs, 32% of toxigenic C. difficile were resulted at 24 hours and 68% at 48 hours. Addition of 17% glycerol to BB-positive aliquots, for -80°C storage, supported 100% retrieval of C. difficile 7 months later. BB with confirmation provides a more sensitive method to detect patient colonization with toxigenic C. difficile and, by using VRE surveillance swabs, does not require additional patient samples. The simplified approach can be deployed across healthcare settings to support C. difficile-prevention programs.