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Bartels Clostridium difficile Toxin A Enzyme Immunoassay (EIA) is intended for the qualitative detection of Clostridium difficile Toxin A in human fecal specimens as an aid in the diagnosis of Clostridium difficile -associate diseases.

The Bartels Clostridium difficile Toxin A EIA is a rapid method for the diagnosis of Clostridium difficile toxin A in human fecal samples, to be used as an aid in the detection of Clostridium difficile-associated disease. Microwell strips are coated with mouse IgG to Clostridium difficile toxin A, which selectively captures Clostridium difficile toxin A if present in a stool sample. Irrelevant specimen debris, including non-toxigenic strains of Clostridium difficile, is washed away. Rabbit immunoglobulins to Clostridium difficile toxin A and peroxidase-labeled goat anti-rabbit antibodies are added to the well concurrently in a coincubation step. During incubation, the rabbit anti- Clostridium difficile toxin A binds to captured toxin A. Peroxidase-labeled anti-rabbit antibodies bind to rabbit antitoxin, forming an antitoxin-conjugate complex. Unbound anti-toxin and conjugate are washed away. Solution 3 and Solution 4 are then added and color is produced if the antitoxin-conjugate complex, which possesses the enzyme for the substrate (HRP), is present. This color production is quantified spectrophotometrically and compared to negative and positive controls for determination of the presence of Clostridium difficile toxin A.

The provided document (K990664) is a 510(k) summary for a modification to an existing device, the Bartels Clostridium difficile Toxin A Enzyme Immunoassay (EIA). The document primarily focuses on demonstrating substantial equivalence of the modified device to the previously cleared device (K913229) based on changes to the assay procedure (incubation times, temperature, and addition of a manual wash method), rather than presenting a full de novo study with detailed acceptance criteria and performance reports for the device's initial market clearance.

Therefore, the requested information, specifically detailed acceptance criteria and the comprehensive study that proves the device meets those criteria, is not fully available within this specific 510(k) modification document. This document mainly confirms that the methodological changes did not adversely affect the device's performance compared to the predicate device.

However, based on the information available and common regulatory practices for 510(k) modifications, I can infer and provide some relevant details:

Missing Information:

• Detailed list of specific acceptance criteria (e.g., sensitivity, specificity thresholds) for the device's initial clearance.
• The comprehensive study report that originally proved the device meets broad acceptance criteria. This document focuses on proving equivalence of a modified procedure.
• Sample size and data provenance for the original clinical studies.
• Number and qualifications of experts for the original ground truth.
• Adjudication method for the original studies.
• Whether an MRMC comparative effectiveness study was done for the original device.
• Effect size of human readers improving with AI vs. without AI assistance (this is an immunoassay, not an AI-based diagnostic).
• Sample size for the original training set (if applicable, for initial development).
• How ground truth for the original training set was established.

Information that can be extracted or inferred from the provided modification document (K990664):

1. A table of acceptance criteria and the reported device performance

Since this is a 510(k) modification for procedural changes, the "acceptance criteria" here refer to demonstrating that the modified procedure performs equivalently to the predicate device whose performance was already established. The document states:

"INTRACEL has made no changes to the manufacturing process or quality control testing procedures for this product. The only changes relate to the incubation and washing conditions employed during performance of the immunoassay. The essential immunoreagents, underlying format and scientific principle remain the same with the improved product."

This implies that the key acceptance criterion for this modification was that the modified assay procedure did not negatively impact the established performance characteristics (sensitivity, specificity, precision, etc.) of the original Bartels C. difficile Toxin A EIA. The document does not list specific numerical performance metrics for the modified device, but rather refers to its equivalence to the predicate.

2. Sample size used for the test set and the data provenance (country of origin of the data, retrospective or prospective)

The document does not explicitly state these details for this specific modification. It implies that the changes were validated through internal testing to confirm equivalence. Usually, for procedural changes in a 510(k) modification, manufacturers would perform comparative studies using clinical samples to show that results are consistent between the old and new procedures. However, the details of such a study (sample size, provenance, retrospective/prospective nature) are not provided in this summary.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

This information is not provided in the document. For an immunoassay like this, the "ground truth" would typically come from a gold standard diagnostic method (e.g., toxigenic culture or a highly validated PCR method) rather than expert consensus on images.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set

Not specified in the document.

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

• No, an MRMC comparative effectiveness study was not done. This device is an Enzyme Immunoassay (EIA) for detecting Clostridium difficile Toxin A, not an AI-based diagnostic or imaging device requiring human reader interpretation. Therefore, the concept of "human readers improving with AI vs. without AI assistance" is not applicable here.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

• Yes, this is a standalone diagnostic test. The Bartels Clostridium difficile Toxin A EIA is an in vitro diagnostic device; its performance is assessed based on its ability to detect the toxin in fecal samples, without human intervention required for its analytical performance beyond running the assay and interpreting the quantitative spectrophotometric result against controls.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)

The document itself does not specify the method for establishing ground truth. However, for a test detecting Clostridium difficile Toxin A, the typical ground truth in clinical validation studies would involve:

• Culture for toxigenic C. difficile strains (cytotoxigenic culture): Considered the gold standard for many years.
• Molecular methods (e.g., PCR for toxin genes): Increasingly used as a gold standard.
• Correlation with clinical outcomes: While not a direct "ground truth" for the presence of toxin, association with clinical disease is crucial for medical devices.

8. The sample size for the training set

This document does not provide details on a "training set" as it relates to machine learning models. For an immunoassay, developmental testing would involve numerous samples, but these are typically not referred to as a "training set" in the context of device regulatory submissions.

9. How the ground truth for the training set was established

Not applicable/not specified for an immunoassay in this context.

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