Equivalent performance of the cobas® Cdiff test for use on the cobas® Liat® system and the cobas® 4800 system

Abstract

Clostridium difficile infection is a significant health burden, and innovative solutions are needed to shorten time to diagnosis and improve infection control. We evaluated the performance of the cobas ® Cdiff test for use on the cobas ® Liat ® System (cobas ® Liat ® Cdiff), a single-sample, on-demand, and automated molecular solution with a 20-min turnaround time. The limit of detection was 45–90 colony-forming units (CFUs)/swab for toxigenic strains that covered the most prevalent toxinotypes, including the hypervirulent epidemic 027/BI/NAP1 strain. Using 442 prospectively collected clinical stool specimens, we compared the performance of the cobas ® Liat ® Cdiff to direct culture and to the cobas ® Cdiff test on the cobas ® 4800 System (cobas ® 4800 Cdiff) – a mediumthroughput molecular platform. The sensitivity and specificity of the cobas ® Liat ® Cdiff compared to direct culture were 93.1% and 95.1%, respectively, and this performance did not statistically differ from the cobas ® 4800 Cdiff ( P > 0.05). Direct correlation of the cobas ® Liat ® and cobas ® 4800 Cdiff tests yielded overall percent agreement of 98.6%. The test performance, automation, and turnaround time of the cobas ® Liat ® Cdiff enable its use for on-demand and out-of-hours testing as a complement to existing batch testing solutions like the cobas ® 4800 Cdiff.