Xpert C. difficile/Epi

The Xpert C. difficile/Epi test is a qualitative in vitro diagnostic test that detects toxin B gene sequences and presumpitively identifies 027/NAP1/BI strains of toxigenic Clostridioides difficile from unformed stool specimens. It is performed on GeneXpert Instrument Systems using automated real-time PCR and is intended as an aid in diagnosing C. difficile infection.

The test uses real-time multiplex PCR with TaqMan probes for automated DNA detection of toxin B (tcdB) gene, binary toxin (CDT) gene, and the tcdC∆117 deletion. It is delivered on single-use, self-contained disposable cartridges and includes internal Sample Processing Control (SPC) and Probe Check Control (PCC) for quality assurance. Results are available in less than 45 minutes.

The device is subject to FDA's Class II Special Controls Guideline document "Toxin Gene Amplification Assays for the Detection of Clostridium difficile" (issued August 27, 2015) under regulation 21 CFR §866.3130. No ISO, IEC, or ASTM standards are explicitly cited in this summary.

The candidate device has identical intended use (detection of C. difficile toxin B gene and presumptive identification of 027/NAP1/BI strains), specimen type (unformed stool), test technology (real-time PCR), test format (disposable cartridge), and automation level as the predicate (cobas Cdiff). While the candidate detects additional targets (binary toxin gene and tcdC∆117 deletion) and uses different instrument platforms (GeneXpert versus cobas Liat), these differences do not raise new or different questions of safety and effectiveness because they represent expanded detection capabilities on an equivalent technological platform. Performance verification studies demonstrated 100% agreement with expected results across all instrument/software combinations and 100% inclusivity with C. difficile strains.