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 hyper-virulent 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 medium-throughput 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.

Performance comparison of the cobas Liat and Cepheid GeneXpert systems for Clostridium difficile detection

“…Another explanation could be real differences in assay sensitivity. Previously performed studies using toxigenic culture as the reference method have independently established comparable sensitivities (> 90%) of the Xpert PCR [ 18 – 20 ] and cobas Liat Cdiff tests [ 9 , 21 ], but much lower sensitivity (< 90%) of the BD Max Cdiff test [ 22 , 23 ]. Despite this lower sensitivity, we chose to use the BD Max Cdiff test for arbitration because it is a readily available, widely used, and FDA-cleared NAAT for detection toxin B gene ( tcdB ) of C .…”

“…The clinical performance of the cobas Liat Cdiff is equivalent to the Xpert PCR. Compared to Xpert PCR and other molecular assays, the cobas Liat Cdiff test provides an even shorter (20 minute) turnaround time and is a fully integrated, portable system that does not require an additional interface to perform testing [ 9 ]. The cobas Liat Cdiff test’s simplicity of use, rapid result reporting, and high sensitivity for C .…”

“…difficile have been cleared by the FDA for diagnostic use [ 8 ]. One such test, the cobas Liat Cdiff nucleic acid test performed on the cobas Liat System (cobas Liat Cdiff; Roche Diagnostics, Pleasanton, CA), offers a rapid, 20-minute, specimen-to-answer, qualitative, real-time PCR result for detecting the tcdB gene [ 9 ].…”

Novel diagnostics for point-of-care bacterial detection and identification

“…The cobas®Liat®Cdiff system is a completely automated approach to the diagnosis of C. difficile-associated diarrhoea by the direct detection of the toxin B (tcdB) gene in patient stool samples. 55 This assay specically detects this toxin gene to assess for a variety of toxigenic C. difficile strains (including a hypervirulent epidemic strain). The cobas®Liat®Cdiff system combines sample preparation, nucleic acid extraction, real-time PCR ampli-cation and detection of target DNA sequences in a single sample analysis that has a turnaround time of 20 minutes, 95.1% speci-city and 93.1% sensitivity, with limit of detection of 45-90 CFU per swab for toxigenic strains.…”

“…The cobas®Liat®Cdiff system combines sample preparation, nucleic acid extraction, real-time PCR ampli-cation and detection of target DNA sequences in a single sample analysis that has a turnaround time of 20 minutes, 95.1% speci-city and 93.1% sensitivity, with limit of detection of 45-90 CFU per swab for toxigenic strains. 55 A similar approach has also been used for the detection of MRSA using the cobas®MRSA/SA test. 56 A magnetic barcode assay system was also the basis for a multiplexed detection platform for S. aureus and K. pneumoniae, 57 which utilized both magnetic nanoparticles and uorescent quantum dots (QDs) for the detection of the target bacteria (Fig.…”