Evaluation of the Liat Cdiff Assay for Direct Detection of Clostridioides difficile Toxin Genes within 20 Minutes

Clostridioides difficile is the main causative agent of antibiotic-associated diarrhea. Prompt diagnosis is required for initiation of timely infection control measures and appropriate adjustment of antibiotic treatment. The cobas Cdiff assay for use on the cobas Liat system enables a diagnostic result in 20 minutes. A total of 252 prospective (n = 150) and retrospective (n = 102) stool specimens from The Netherlands, France, and Switzerland were tested on the cobas Cdiff assay using the Xpert C. difficile assay as a reference method. The overall positive and negative percent agreement (PPA and NPA, respectively) of the cobas Cdiff assay compared with the Xpert C. difficile assay was 98.0% (100/102; 95% confidence interval [CI], 93.1% to 99.5%) and 94.0% (141/150; 95% CI, 89.0% to 96.8%), respectively. When comparing the PPAs of cobas Cdiff and Xpert C. difficile with culture, the results were 91.7% (55/60; 95% CI, 81.9% to 96.4%) and 85.0% (51/60; 95% CI, 73.9% to 91.9%), respectively. The difference was not statistically significant. The cobas Cdiff assay offers a very rapid alternative for diagnosing C. difficile infection. The 20-minute turnaround time provides the potential for point-of-care testing so that adequate infection control measures can be initiated promptly.