(254 days)
The BinaxNOW® Staphylococcus aureus Test is a qualitative, in vitro immunochromatographic assay for the presumptive identification of Staphylococcus aureus. The test is performed directly on blood culture samples positive for Gram-positive cocci in clusters. The BinaxNOW® Staphylococcus aureus Test is not intended to diagnose Staphylococcus aureus nor to guide or monitor treatment for Staphylococcus aureus infections. Subculturing positive blood cultures is necessary to recover organisms for susceptibility testing and/or differentiation of mixed growth.
The BinaxNOW" Staphylococcus aureus Test is a rapid immunochromatographic membrane assay that uses highly sensitive polyclonal antibodies to detect a Staphylococcus aureus specific protein directly from blood cultures which have been identified as being positive for Gram-positive cocci in clusters. These antibodies and a control antibody are immobilized onto a test strip as two distinct lines and combined with other reagents/pads. This test strip is mounted inside a cardboard, book-shaped hinged test device. Specimens are aliquots from blood cultures which have been identified as positive for Gram-positive cocci in clusters. After the sample is prepared, it is added to the sample pad at the top of the test strip and the device is closed. Results are read at 10 minutes.
Here's a summary of the acceptance criteria and the study details for the BinaxNOW® Staphylococcus aureus Test, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Clinical Performance | |
| Positive Agreement (Sensitivity) | 98.8% (95% C.I.: 93.6 - 99.8%) |
| Negative Agreement (Specificity) | 100.0% (95% C.I.: 98.4% - 100.0%) |
| Analytical Sensitivity (Limit of Detection) | 5.42 x 10^8 cells/mL (96% detection at this concentration) |
| Analytical Reactivity | Detected 54 known pathogenic Staphylococcus aureus strains. |
| Analytical Specificity (Cross-Reactivity) | No false positives with a panel of coagulase-negative Staphylococcus strains, yeasts, and numerous non-staphylococcal strains. |
| Interfering Substances | No false results with 20 potentially interfering substances (anti-inflammatory drugs, antibiotics, endogenous blood components, anticoagulant). |
| Reproducibility | 98% (588/600) agreement with expected test results across multiple sites, days, runs, and operators. |
2. Sample Size Used for the Test Set and the Data Provenance
- Sample Size (Clinical Performance Study): 325 blood culture samples.
- Data Provenance: Retrospective and/or prospective (not explicitly stated if combined or separate, but clinical performance was "established in a multicenter clinical study conducted in 2008-09"). The data originated from three geographically-diverse hospital laboratories within the US.
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 BinaxNOW® Staphylococcus aureus Test performance was compared "to standard methods used routinely by the testing laboratories." It does not specify the number of experts or their qualifications for establishing the ground truth, but implies it was based on established laboratory protocols and potentially expert interpretation where applicable for "standard methods." The reference method essentially serves as the "ground truth."
4. Adjudication Method for the Test Set
- The document does not describe a specific adjudication method (like 2+1 or 3+1). The comparison was made against "standard methods used routinely by the testing laboratories," suggesting that the results from these standard methods were taken as the truth without further expert adjudication beyond the routine lab procedures.
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, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This device is an in vitro diagnostic (IVD) assay, not an AI-assisted diagnostic tool for human readers. Its performance is evaluated independently or against a reference method.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done
- Yes, the clinical performance study evaluated the standalone performance of the BinaxNOW® Staphylococcus aureus Test. It's an immunochromatographic assay that provides a direct result, not an aid to a human reader. Its results were compared directly to the reference method without human interpretation as part of the device's output.
7. The Type of Ground Truth Used
- The ground truth for the clinical performance study was established using "standard methods used routinely by the testing laboratories." For an IVD like this, this typically refers to recognized microbiological culture and identification techniques, which are considered the gold standard for bacterial identification.
8. The Sample Size for the Training Set
- The document does not explicitly mention a "training set" in the context of device development or clinical trials. This is common for rapid immunochromatographic assays, where development involves analytical studies (reactivity, specificity, sensitivity) and then validation in clinical samples. The "training set" concept is more pertinent to machine learning algorithms.
9. How the Ground Truth for the Training Set Was Established
- As a "training set" is not explicitly mentioned for this type of device, the method for establishing its ground truth is not applicable or described in the provided text. The analytical studies (reactivity, specificity) used well-characterized bacterial strains (e.g., ATCC, NARSA strains) for which the identity was already known, serving a similar function to establishing "ground truth" for those specific analytical evaluations.
§ 866.2660 Microorganism differentiation and identification device.
(a)
Identification. A microorganism differentiation and identification device is a device intended for medical purposes that consists of one or more components, such as differential culture media, biochemical reagents, and paper discs or paper strips impregnated with test reagents, that are usually contained in individual compartments and used to differentiate and identify selected microorganisms. The device aids in the diagnosis of 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.