(154 days)
The Great Basin Portrait™ GBS Assay, performed on the PA500 Portrait™ Analyzer System, is a qualitative in vitro diagnostic test (IVD) for the detection of Group B Streptococcus (GBS) DNA from vaginal/rectal swabs from antepartum women, following enrichment in LIM Broth for 18 - 29 hours. The assay utilizes automated sample preparation and polymerase chain reaction (PCR) to amplify a cfb gene sequence specific to the Streptococcus agalactiae (GBS) genome which is detected by hybridization probes immobilized on a silica chip surface.
Results from the Portrait™ GBS Assay can be used as an aid in determining colonization status in antepartum women. The Portrait™ GBS Assay does not provide susceptibility results. Cultured isolates are needed for performing susceptibility testing as recommended for penicillin-allergic women.
The Portrait™ GBS Assay is intended for use in clinical laboratory, and reference laboratory settings. The Portrait™ GBS Assay is not intended for point of care use.
The Great Basin PA500 Portrait Analyzer System is a fully automated system that includes the Portrait Analyzer, single-use Portrait GBS Assay Test Cartridges, and the Portrait data analysis software. The PA500 Portrait Analyzer System is designed to perform automated sample preparation, PCR, and optical chip-based detection with integrated data analysis in approximately 90 minutes. The Great Basin Portrait™ GBS Assay utilizes automated hot-start PCR technology to amplify target nucleic acid sequences that are detected using species-specific S. agalactiae DNA hybridization probes immobilized on a modified silicon chip surface.
Here's a breakdown of the acceptance criteria and the study details for the Portrait™ GBS Assay based on the provided document:
Acceptance Criteria and Reported Device Performance
Device Name: Portrait™ GBS Assay
| Acceptance Criteria | Reported Device Performance (%) (95% CI) |
|---|---|
| Sensitivity | 97.9% (92.7% - 99.4%) |
| Specificity | 96.0% (93.5% - 97.6%) |
| Positive Predictive Value (PPV) | 86.9% (79.2% - 92.0%) |
| Negative Predictive Value (NPV) | 99.4% (97.9% - 99.8%) |
Note: The document does not explicitly state pre-defined acceptance criteria values for sensitivity, specificity, PPV, or NPV in the "510(k) Summary" section. Instead, these are presented as the "overall assay performance" observed during the clinical study.
Study Details
2. Sample size used for the test set and the data provenance:
- Sample Size: 448 compliant clinical samples.
- Data Provenance: From three clinical sites in the United States. The study was prospective, as samples were "run over the course of four months to evaluate the performance."
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The document states that the Portrait™ GBS Assay performance was compared "to the reference GBS clinical microbiology protocol." This implies standard laboratory culture methods were used as the gold standard. There is no mention of human experts establishing the ground truth for the test set in this context.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set:
- None explicitly mentioned as human adjudication; the reference standard was the "GBS clinical microbiology protocol" (culture).
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 involving human readers and AI assistance was not performed or described. This device is an in vitro diagnostic (IVD) assay for molecular detection, not an AI-powered image analysis or diagnostic support tool for human readers.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Yes, the clinical performance study evaluated the Portrait™ GBS Assay as a standalone diagnostic tool, comparing its results directly against the reference culture method. The "algorithm" here refers to the automated PCR technology, sample preparation, and optical chip-based detection with integrated data analysis within the PA500 Portrait™ Analyzer System.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The ground truth used was GBS culture testing (the "reference GBS clinical microbiology protocol"). This is a recognized laboratory gold standard for detecting GBS colonization.
8. The sample size for the training set:
- The document does not specify a separate training set sample size. The analytical studies describe various experiments (LoD, inclusivity, exclusivity, interference, carry-over, reproducibility) that might contribute to the development and refinement of the assay and its software, but these are not explicitly labeled as a "training set" in the context of machine learning, which is not the primary mechanism of this device. For an IVD like this, validation often involves demonstrating performance across various analytical and clinical scenarios rather than "training" an AI model.
9. How the ground truth for the training set was established:
- As no explicit "training set" for an AI model is described, the mention of ground truth establishment for such a set is not applicable. For the analytical studies, the ground truth for spiked samples was known by design (e.g., specific GBS strains at known concentrations, or known interfering substances).
§ 866.3740
Streptococcus spp. serological reagents.(a)
Identification. Streptococcus spp. serological reagents are devices that consist of antigens and antisera (excluding streptococcal exoenzyme reagents made from enzymes secreted by streptococci) used in serological tests to identifyStreptococcus spp. from cultured isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by bacteria belonging to the genusStreptococcus and provides epidemiological information on these diseases. Pathogenic streptococci are associated with infections, such as sore throat, impetigo (an infection characterized by small pustules on the skin), urinary tract infections, rheumatic fever, and kidney disease.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 866.9.