Simultaneous detection of Clostridioides difficile glutamate dehydrogenase and toxin A/B: Comparison of the C. DIFF QUIK CHEK COMPLETE and RIDASCREEN Assays

Various commercial assays have recently been developed for detecting glutamate dehy-drogenase (GDH) and/or toxin A/B to diagnose Clostridioides difficile infection (CDI). We compared the performance of two assays for the simultaneous detection of C. difficile GDH and toxin A/B, using 150 stool samples: C. DIFF QUIK CHEK COMPLETE (QCC; TechLab, Blacksburg, VA, USA) and RIDASCREEN Clostridium difficile GDH (RC-GDH) and Toxin A/B (RC-Toxin A/B; R-Biopharm, Darmstadt, Germany). For GDH detection, QCC and RC-GDH showed satisfactory sensitivity (95.7% and 94.3%, respectively) and specificity (92.5% and 93.8%, respectively) compared with C. difficile culture. For toxin A/B detection, QCC showed higher sensitivity than RC-Toxin A/B (60.0% vs 33.3%, P<0.001) compared with toxigenic C. difficile culture. When the results of QCC or RC-GDH+RC-Toxin A/B were used as the first step of a two-step algorithm for diagnosing CDI, QCC permitted more accurate discrimination than RC of positive or negative results for CDI (77.3% and 65.3%, respectively). QCC is useful for the simultaneous detection of C. difficile GDH and toxin A/B as a part of the two-step algorithm for diagnosing CDI.