Traditional methods for identification of Clostridium difficile (C.difficile) include toxigenic culture, which is labor intensive and slow, and enzyme immunoassays (EIA), which have limited sensitivity. Algorithms have been developed using combinations of EIA testing to overcome shortcomings of individual assays.1 However, these algorithms may introduce delays in reporting results to physicians, which adversely impacts patient management.
Molecular technologies (including nucleic acid amplification tests [NAAT]) offer better sensitivity and turnaround time in identifying toxigenic C. difficile when compared to several other approaches (glutamate dehydrogenase [GDH] assay, toxin A and B immunoassay, cell culture cytotoxicity neutralization assay), either alone or in combination.1
In recent years, the frequency and severity of C. difficile-associated disease has continued to increase, prompting a need for rapid and reliable C. difficile testing, particularly in vulnerable elderly populations. By rapidly detecting C. difficile in patient stool
samples, the cobas® Cdiff Test combines high assay sensitivity with rapid turnaround time and a minimum number of pre-analytic steps, to facilitate earlier intervention of patients suffering from C. difficile-associated disease.
In a study of >1,200 samples, the cobas® Cdiff Test demonstrated superior performance compared to direct culture cytotoxicity testing.
The performance that clinical confidence demands
The cobas® Cdiff Test delivers sensitivity and specificity that Roche real-time polymerase chain reaction (PCR) can provide.
The cobas® Cdiff Test:
Provides confidence in results
When compared to direct culture cytotoxicity and a molecular method, the cobas® Cdiff Test demonstrated the following sensitivity, specificity, positive predictive values, and negative predictive values:
|Direct Culture Cytoxicity Comparison*|
|Positive Predictive Value||83%|
|Negative Predictive Value||100%|
|Molecular Method Comparison*|
|Positive Predictive Value||94%|
|Negative Predictive Value||99%|
* Performance comparison in a study of >1,200 samples
Make every sample count
When compared to a CE- and FDA-cleared NAAT, the cobas® Cdiff Test had a 4x lower inhibition rate and a 2x lower total error rate. A lower inhibition rate means fewer repeat samples, less chances for error, and better patient care.
cobas® Cdiff test inhibition rate
cobas® Cdiff test total error rate
Less hands-on time means more walk-away time
The cobas® Cdiff Test requires up to 74% less hands-on time than competitor platforms.
Run mixed batch assays
The cobas® 4800 System offers flexibility with parallel sample processing capabilities. cobas® Cdiff Test samples can be run with different tests and sample types in one run.
Run mixed batch assays of:
In addition to parallel sample processing, the cobas® 4800 System offers an expanding test menu.
|cobas® Cdiff Assay Performance and Specifications|
|Sample Type||Unformed stool specimen|
|Sample Processing||Simple handling, automated processing on the cobas® 4800 System|
|Target Region||C. difficile Toxin B (tcdB)|
|Analytical Sensitivity||100% (31 toxinotypes detected)|
|Analytical Specificity||100% (no cross reactivity across 98 bacteria, virus, fungi)|
|Limit of Detection||225 CFU/mL|
|Workflow||Mixed batch capability; optimized sample loading|
*Compared with direct culture cytotoxicity test
Intended Use: The cobas® Cdiff Test on the cobas® 4800 System is an automated, qualitative in vitro diagnostic test, that utilizes real-time polymerase chain reaction (PCR), for the direct detection of the toxin B (tcdB) gene of toxigenic Clostridium difficile in unformed (liquid or soft) stool specimens obtained from patients suspected of having C. difficile infection (CDI). The cobas® Cdiff Test is intended for use as an aid in the diagnosis of CDI in humans in conjunction with clinical and epidemiological risk factors.
1. Surawicz et al. Guidelines for diagnosis, treatment, and prevention of Clostridium difficile infections. Am J Gastroenterol. 2013 Apr;108(4):478-98.