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The Cepheid Xpert® GBS LB Control Panel is intended for use as external assayed positive and negative quality control materials to monitor the performance of in vitro laboratory nucleic acid testing procedures for the qualitative detection of Group B Streptococcus (GBS) performed with the Cepheid Xpert® GBS LB Assay on the GeneXpert® Instrument System. The controls comprise cultured and inactivated Streptococcus agalactiae as the positive control and Lactobacillus acidophilus as the negative control.

The Cepheid Xpert® GBS LB Control Panel is not intended to replace manufacturer controls provided with the device.

The Cepheid Xpert® GBS LB Control Panel is used to monitor the extraction, amplification and detection of the Cepheid Xpert® GBS LB Assay. The Cepheid Xpert® GBS LB Control Panel contains authentic pathogens inactivated by temperature treatments. Each Cepheid Xpert® GBS LB Control Panel consists of 6 individually packaged positive control swabs and 6 individually wrapped negative control swabs. Each positive control swab contains Streptococcus agalactiae (Lancefield's Group B) as well as preservatives and stabilizers. Each negative control swab contains Lactobacillus as well as preservatives and stabilizers. Each swab is individually wrapped with a desiccant in a heat-sealed foil pouch.

Here's a breakdown of the acceptance criteria and study information for the Cepheid Xpert GBS LB Control Panel, based on the provided document:

1. Acceptance Criteria and Reported Device Performance

The document describes a precision and reproducibility study to demonstrate device performance. The acceptance criteria are implicitly 100% agreement for both analytes (S. agalactiae and L. acidophilus) across different sites, operators, and lots.

Note: The reported device performance for both analytes shows 100% agreement, meeting the implicit acceptance criteria. One ERROR result was obtained for S. agalactiae at Site 1 but was retested with expected results, suggesting the device itself performed correctly once the test was properly executed.

2. Sample Size and Data Provenance

• Test Set Sample Size: The study involved a total of 90 tests for each analyte.
  • 3 testing locations
  • 6 operators (2 per facility)
  • 3 different lots of the control panel
  • Each operator performed 3 tests (1 per lot) on 5 different days.
  • Calculation: 3 (lots) * 5 (days) * 2 (operators/site) * 3 (sites) for each analyte = 90 tests per analyte.
• Data Provenance: The document does not explicitly state the country of origin. This was a prospective study conducted for the purpose of demonstrating performance for this 510(k) submission.

3. Number of Experts and Qualifications for Ground Truth (Test Set)

Not applicable as this is a quality control material where the expected outcome (positive or negative for specific bacteria) is predetermined by the composition of the control. The "ground truth" is inherent to the control material itself (i.e., S. agalactiae is present in the positive control, L. acidophilus in the negative control).

4. Adjudication Method for the Test Set

Not applicable. The study measures agreement with the expected result of known positive and negative controls, not subjective interpretation requiring adjudication among experts.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

Not applicable. This is a study of a quality control material, not a diagnostic device that requires human interpretation. Therefore, there's no "human readers" to compare performance with or without AI assistance.

6. Standalone Performance Study

Yes, a standalone performance study was conducted. The study evaluated the performance of the Cepheid Xpert GBS LB Control Panel when used with the Cepheid Xpert GBS LB Assay on the GeneXpert Instrument System. The results (100% agreement) demonstrate the device's ability to consistently produce the expected outcome.

7. Type of Ground Truth Used

The ground truth used is the known composition of the quality control materials. The positive control contains Streptococcus agalactiae (known to be detected by the assay as GBS positive), and the negative control contains Lactobacillus acidophilus (known not to be detected by the assay as GBS positive).

8. Sample Size for the Training Set

Not applicable. This device is a quality control material, not an AI/ML algorithm that requires a training set. Its performance is evaluated based on its consistency and accuracy in producing predetermined results when tested.

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

Not applicable, as there is no training set for this device.

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