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510(k) Data Aggregation
(52 days)
The illumigene C. difficile DNA amplification assay, performed on the illumipro-10, is a qualitative in vitro diagnostic test for the direct detection of toxigenic C. difficile in human stool specimens from pediatric and adult patients suspected of having Clostridium difficile-associated disease (CDAD).
The illumigene C. difficile assay utilizes loop-mediated isothermal DNA amplification (LAMP) technology to detect the pathogenicity locus (PaLoc) of toxigenic Clostridium difficile PaLoc is a gene segment present in all known toxigenic C. difficile strains. The C. difficile PaLoc codes for both the Toxin A gene (tcdA) and the Toxin B gene (tcdB), has conserved border regions, and is found at the same site on the C. difficile genome for all toxigenic strains. The illumigene C. difficile assay detects the Paloc by targeting a partial DNA fragment on the Toxin A gene. The tcdA target region was selected as an intact region remaining in all known A+B+ and A-B+ toxinotypes.
illumigene C. difficile is intended for use in hospital, reference or state laboratory settings. The device is not intended for point-of-care use.
The illumigene Molecular Diagnostic Test System is comprised of the illumigene C. difficile DNA Amplification Test Kit, the illumigene C. difficile External Control Kit and the illumipro-10 Automated Isothermal Amplification and Detection System. The illumigene C. difficile DNA amplification assay utilizes loop-mediated isothermal amolification (LAMP) technology to detect the presence of toxigenic C. difficile in patients suspected of having C. difficile associated disease (CDAD). Each illumigene C. difficile assay is completed using an illumigene Sample Preparation Apparatus. Illumigene Reaction Buffer, illumigene C. difficile Test Device, Sample Collection Brush, and illumigene Extraction Tube. Samples are prepared using the Sample Collection Brush and the illumigene Sample Collection Apparatus, target DNA is heat extracted in the Extraction Tube and DNA amplification occurs in the illumigene C. difficile Test Device.
The illumipro-10 heats each illumigene C. difficile Test Device containing prepared samples, facilitation of target DNA. When toxigenic C. difficile is present in the patient specific sequence is amplified and Magnesium pyrophosphate is formed. Magnesium pyrophosphate in the reaction mixture. The illumipro-10 detects the change in light transmission mixture created by the precipitating Magnesium pyrophosphate. Sample results are reported as Positive based on the detected change in transmission.
The illumigene C. difficile External Control Kit consists of a Positive Control Reagent. External Control reagents are provided to aid the user in detection of reagent deterioration, adverse environmental or test conditions, or variance in operator performance that may lead to test errors. The illumigene C. difficile External Control Kit is required for routine Quality Control.
The illumigene C. difficile DNA amplification assay is a qualitative in vitro diagnostic test for the direct detection of toxigenic C. difficile in human stool specimens from pediatric and adult patients suspected of having Clostridium difficile-associated disease (CDAD). The assay detects a partial DNA fragment on the Toxin A gene within the pathogenicity locus (PaLoc) of toxigenic C. difficile.
1. Table of acceptance criteria and reported device performance:
The document does not explicitly state pre-defined acceptance criteria values for sensitivity and specificity. However, based on the presented clinical trial results, the observed performance metrics can be considered the demonstrated performance of the device.
| Performance Metric | Acceptance Criteria (Implicit from reference K100818) | Reported Device Performance (Patients ≥ 2 years) | Reported Device Performance (Patients < 2 years) |
|---|---|---|---|
| Sensitivity | Not explicitly stated (predicate device performance) | 95.2% (95% CI: 89.2% - 97.9%) | 93.3% (95% CI: 78.7% - 98.2%) |
| Specificity | Not explicitly stated (predicate device performance) | 95.3% (95% CI: 93.2% - 96.7%) | 96.3% (95% CI: 92.2% - 98.3%) |
| Invalid Rate | Not explicitly stated | 2.9% (20/697) | 0.5% (1/193) |
2. Sample size used for the test set and the data provenance:
- Patients ≥ 2 years of age: 697 qualified patient samples.
- Patients < 2 years of age: 193 qualified patient samples.
- Data Provenance: The samples were collected from independent clinical test sites located in the Midwestern and Southern regions of the United States, and from the manufacturer. This indicates prospective clinical studies conducted in the US.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
The ground truth was established by cytotoxic bacterial culture. This is a laboratory-based method and does not involve human expert interpretation in the same way as, for example, a radiologist reading an image. Therefore, the concept of "number of experts" or their specific qualifications (e.g., years of experience for image interpretation) is not directly applicable here. The validity of the cytotoxic bacterial culture would rely on standard laboratory protocols and accredited personnel.
4. Adjudication method for the test set:
Not explicitly mentioned for the comparison to cytotoxic bacterial culture. However, for discordant results (false positives/negatives), another FDA cleared molecular assay for C. difficile detection or for detection of GDH (Glutamate Dehydrogenase) was used for further investigation. This suggests a form of secondary assessment or confirmation for discrepant results, but not an "adjudication method" in the typical sense of expert consensus on initial interpretations.
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:
This is a diagnostic device for molecular detection, not an imaging device requiring human reader interpretation in the context of an MRMC study. Therefore, an MRMC comparative effectiveness study was not applicable and not performed. The device provides a direct positive/negative result.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
Yes, the device was evaluated in a standalone manner. The "illumigene C. difficile DNA amplification assay, performed on the illumipro-10" directly provides results as "Positive" or "Negative" based on detected changes in light transmission, without human interpretation of the assay's primary output. Human involvement is in sample preparation and loading, and interpreting the final reported result from the instrument.
7. The type of ground truth used:
The ground truth used was cytotoxic bacterial culture.
8. The sample size for the training set:
The document does not explicitly state a separate "training set" for the clinical performance evaluation. The clinical trials (697 patients ≥ 2 years and 193 patients < 2 years) appear to represent the primary evaluation/test sets against the established ground truth. For analytical sensitivity and reproducibility, specific dilutions and contrived samples were used, which are more akin to analytical validation rather than a clinical training set.
9. How the ground truth for the training set was established:
As no explicit "training set" for clinical performance was described in the same way as the test set, the method for establishing ground truth for a training set is not detailed. However, if any development work involved culture-confirmed samples, the ground truth would have been established by similar laboratory methods like cytotoxic bacterial culture or culture confirmed C. difficile strains (e.g., for analytical sensitivity). For the analytical studies, "natural negative" and "contrived positive" samples were prepared, with the "natural negative" samples confirmed by cytotoxic bacterial culture.
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