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The Cepheid Xpert® C. difficile/Epi Control Panel is intended for use as external assayed positive and negative quality controls to monitor the performance of in vitro laboratory nucleic acid testing procedures for the qualitative detection of Clostridioides (Clostridium) difficile performed with the Cepheid Xpert® C. difficile/Epi assay on the GeneXpert® Dx System. The controls comprise cultured and inactivated Clostridioides (Clostridium) difficile 027-NAP1-B1 as the positive control and Clostridium sordellii as the negative control.

The Cepheid Xpert® C. difficile/Epi Control Panel is not intended to replace manufacturer controls provided with the device.

Device Description

The Cepheid Xpert® C. difficile/Epi Control Panel to monitor DNA extraction, amplification and detection of the Cepheid Xpert® C. difficile/Epi assay. The Cepheid Xpert® C. difficile/Epi Control Panel contains cultured microorqanisms inactivated by heat treatments. Each Cepheid Xpert® C. difficile/Epi Control Panel consists of 6 individually packaged positive control swabs and 6 individually wrapped negative control swabs. Each positive control swab contains cultured and inactivated Clostridioides difficile at a target level that is designed to provide reproducible performance above the limit of detection of the Cepheid Xpert® C. difficile/Epi assay. The positive control swab is expected to produce positive results for each of the genes targeted by the Cepheid Xpert® C. difficile/Epi assay: toxin B (tcdB), binary toxin (CDT) and the variant requlator gene, tcdC. Each negative control swab contains Clostridium sordelli. Each swab is individually wrapped with a desiccant in a heat-sealed foil pouch.

AI/ML Overview

Here's an analysis of the provided text to fulfill your request regarding acceptance criteria and the study proving device performance:

Device Name: Cepheid Xpert C. difficile/Epi Control Panel

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state "acceptance criteria" in a codified manner for a diagnostic accuracy study (e.g., target sensitivity, specificity). Instead, it presents the results of a precision and reproducibility study to demonstrate the performance of the control panel itself. The implicit acceptance criterion for a control panel is 100% agreement with the expected result (positive controls yield positive results, negative controls yield negative results).

Acceptance Criteria (Implied)	Reported Device Performance
Positive Controls: 100% agreement with expected positive results	Clostridioides difficile: 91/91 (100%) agreement
Negative Controls: 100% agreement with expected negative results	Clostridium sordellii: 91/91 (100%) agreement
Consistent Ct values (low %CV) across sites and operators	Mean Ct (%CV) for tcdB: 29.5 (2.2)
	Mean Ct (%CV) for Binary Toxin: 28.9 (2.2)
	Mean Ct (%CV) for tcdC: 28.8 (2.2)
	Mean Ct (%CV) for SPC (Negative Controls): 32.5 (2.0)

2. Sample Size Used for the Test Set and Data Provenance

Test Set Sample Size: 91 positive control tests and 91 negative control tests.
- For the positive control: 30 at Site 1, 31 at Site 2, 30 at Site 3.
- For the negative control: 30 at Site 1, 31 at Site 2, 30 at Site 3.
Data Provenance: The document does not specify the country of origin. The study was conducted as a "precision and reproducibility study," which is typically prospective, designed to evaluate product consistency.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of those Experts

Not applicable. This study evaluates a quality control panel, not a diagnostic device's ability to identify disease in patient samples. The "ground truth" for the test set is established by the known composition of the control panel itself (i.e., the positive control contains C. difficile, and the negative control contains C. sordellii). There are no human experts classifying images or results for ground truth in this context.

4. Adjudication Method for the Test Set

Not applicable. As noted above, the "ground truth" is inherent in the design of the control panel. The performance is assessed against the expected molecular detection profile of the contained microorganisms.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance

Not applicable. This is a study for a quality control panel, not an AI-powered diagnostic device. No human readers or AI assistance are involved in interpreting the results beyond standard laboratory procedures for running the GeneXpert® Dx System.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

The study inherently evaluates the "standalone" performance of the control panel in conjunction with the Cepheid Xpert® C. difficile/Epi assay on the GeneXpert® Dx System. The control panel is a reagent designed to monitor the assay's performance. The results (presence/absence of targets, Ct values) are generated directly by the GeneXpert system without further human interpretation beyond confirming the system's output.

7. The Type of Ground Truth Used

The ground truth is based on the known composition of the manufactured control materials. The positive control contains cultured and inactivated Clostridioides difficile, and the negative control contains Clostridium sordellii. The expected results are therefore known beforehand based on the microbial content.

8. The Sample Size for the Training Set

Not applicable. This device is a quality control panel, not an algorithm or AI system that requires a "training set." The study evaluated the performance of the manufactured controls.

9. How the Ground Truth for the Training Set Was Established

Not applicable (as described in point 8).

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