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The Panther Fusion GBS assay is an automated qualitative in vitro diagnostic test utilizing real-time PCR for detection of Group B Streptococcus DNA from either Lim or Carrot enrichment broth cultures of vaginal/rectal swabs from antepartum women following 18-24 hours incubation.

This test is performed on the Hologic Panther Fusion system and is intended to aid in determining the GBS colonization status of antepartum women. This assay does not diagnose or monitor treatment for GBS infections. The Panther Fusion GBS assay does not provide susceptibility results. Culture isolates are needed for performing susceptibility testing as recommended for penicillin-allergic women.

The Panther Fusion GBS assay involves the following steps: Sample lysis, nucleic acid capture and elution, and multiplex RT-PCR where analytes (when present) are simultaneously amplified, detected and differentiated. Nucleic acid capture and elution takes place in a single tube on the Panther Fusion system. The eluate is transferred to the Panther Fusion system reaction tube containing the assay reagents. RT-PCR is then performed for the eluted nucleic acid on the Panther Fusion system.

Sample Collection and Enrichment: After collecting and transporting a swab sample to the laboratory, the swab is placed in Lim Broth or Carrot Broth for 18 to 24 hours of enrichment. Prior to testing on the Panther Fusion system, enriched specimens are then transferred to a tube containing specimen transport media (STM) that lyses the cells, releases target nucleic acid and protects them from degradation during storage.

Nucleic Acid Capture and Elution: Specimens are then first incubated in an alkaline reagent (FER-X) to enable cell lysis. The Internal Control (IC-X) is added to each test specimen and controls via the working Panther Fusion capture Reagent-X (wFCR-X). The IC-X monitors specimen processing, amplification and detection. Magnetic particles with covalently bound oligonucleotides, contained in Panther Fusion capture Reagent-X (FCR-X), mediate the nucleic acid capture by hybridizing to total nucleic acid in the test specimen. The capture nucleic acids are then separated from residual specimen matrix in a magnetic field by a series of wash steps with a mild detergent. The captured nucleic acid is then eluted from the magnetic particles with a reagent of low ionic strength (Panther Fusion Elution Buffer).

Elution transfer and PCR: During the elution transfer step, eluted nucleic acid is transferred to a Panther Fusion Reaction tube already containing oil and reconstituted mastermix. PCRbased target amplification subsequently occurs with target-specific forward and reverse primers, generating a fluorescence signal. The Panther Fusion GBS Software computes a cycle threshold result (Ct) to qualitatively determine the presence of the analyte targets and corresponding fluorescent channels used in the Panther Fusion GBS Assay are summarized in the Table 1 below.

The document describes the Panther Fusion GBS Assay, an automated qualitative in vitro diagnostic test for the detection of Group B Streptococcus DNA. The acceptance criteria and the study proving the device meets these criteria are outlined in sections G, H, and I of the 510(k) summary.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are generally implied by the performance metrics aimed for during the studies. While explicit "acceptance criteria" are not listed in a dedicated table, the studies aim to demonstrate high sensitivity and specificity as is standard for such diagnostic tests.

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

• Test Set Sample Size: A total of 947 clinical leftover samples.
• Data Provenance: The study was conducted from January 2018 to March 2018 at three geographically distinct sites in the United States. The data was obtained from prospective collection of leftover enriched culture samples (Lim broth and Carrot broth) from vaginal/rectal specimens from antepartum women during routine GBS screening. This is considered prospective for the purpose of the study as the samples were collected and then tested by the investigational device and reference method.

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

The document does not explicitly state the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience") used to establish the ground truth. However, the ground truth was established by the reference culture method following CDC recommendations. This implies that the laboratory personnel performing and interpreting these cultures are qualified, but specific details are not provided in this summary.

4. Adjudication Method for the Test Set

The document states that results obtained using the Panther Fusion GBS Assay were compared to those obtained with the reference method. It doesn't describe a specific adjudication method (e.g., 2+1, 3+1) if there were discrepancies between the investigational device and the reference method. For the 16 false positives in Lim Broth, it notes that 14 (87.5%) were positive on the Becton Dickinson BD MAX GBS Assay, suggesting some form of secondary verification for discordant results, but not a formal adjudication process involving multiple human readers as might be found in an imaging study.

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

No, an MRMC comparative effectiveness study was not done. This type of study is typically performed for diagnostic imaging devices where human interpretation is a key component, comparing human reader performance with and without AI assistance. The Panther Fusion GBS Assay is an in vitro diagnostic (IVD) device, where the result is determined by the instrument/assay, not by human interpretation of complex images.

6. Standalone (Algorithm Only) Performance

Yes, this study essentially represents standalone performance of the Panther Fusion GBS Assay. The device is an automated qualitative in vitro diagnostic test. Its performance (sensitivity, specificity) is measured directly against the reference standard without human 'in-the-loop' assistance from the device output for diagnosis. The output (positive/negative) is the direct result of the algorithm.

7. Type of Ground Truth Used

The ground truth used was the reference culture method following CDC recommendations. This is a laboratory-based, established gold standard for GBS colonization status.

8. Sample Size for the Training Set

The document does not provide information on the sample size for the training set. This 510(k) summary focuses on the validation of the finished device (the "test set" in the context of typical AI/ML development), not the development or training process of the assay components. For molecular diagnostic assays, while there's an underlying 'algorithm' (primer design, probe chemistry, cutoff values), it's not typically an AI/ML algorithm that learns from a dataset in the way a deep learning model would. Therefore, a distinct "training set" in the AI/ML sense is not described.

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

Since information about a dedicated "training set" in the AI/ML sense is not provided, the method for establishing its ground truth is also not described. For an IVD assay like this, the "training" involved designing and optimizing the molecular components (primers, probes) and establishing the cut-off values for detection based on analytical studies and perhaps smaller internal development studies. The ground truth for such optimization would similarly rely on controlled lab experiments and reference methods, but is not detailed here.

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