(252 days)
The Clearview® Exact PBP2a Test is a qualitative, in vitro immunochromatographic assay for the detection of penicillin-binding protein 2a (PBP2a) in isolates identified as Staphylococcus aureus, as an aid in detecting methicillin-resistant Staphylococcus aureus (MRSA). The Clearview® Exact PBP2a Test is not intended to diagnose MRSA nor to guide or monitor treatment for MRSA infections.
The Clearview® Exact PBP2a Test is a rapid immunochromatographic membrane assay that uses highly sensitive monoclonal antibodies to detect the PBP2a protein directly from bacterial isolates. These antibodies and a control antibody are immobilized onto a nitrocellulose membrane as two distinct lines and combined with a sample pad, a blue conjugate pad, and an absorption pad to form a test strip.
Isolates are sampled directly from the culture plate and eluted into an assay tube containing Reagent 1. Reagent 2 is then added and the dipstick is placed in the assay tube. Results are read visually at 5 minutes.
The Clearview® Exact PBP2a Test is a rapid immunochromatographic assay for detecting penicillin-binding protein 2a (PBP2a) in Staphylococcus aureus isolates, aiding in the detection of methicillin-resistant Staphylococcus aureus (MRSA).
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state pre-defined acceptance criteria. However, it reports sensitivity and specificity performance values for the device compared to a reference method. We can infer that the reported performance values were considered acceptable for regulatory clearance.
| Performance Metric | Reported Device Performance (Tryptic Soy Agar with 5% sheep blood) | Reported Device Performance (Columbia Agar with 5% sheep blood) | Reported Device Performance (Mueller Hinton with 1 µg oxacillin induction) |
|---|---|---|---|
| Sensitivity | 98.1% (95.2-99.3% CI) | 99.0% (96.6-99.7% CI) | 99.5% (97.4-99.9% CI) |
| Specificity | 98.8% (96.5-99.6% CI) | 98.8% (96.5-99.6% CI) | 98.8% (96.5-99.6% CI) |
2. Sample Size and Data Provenance for the Test Set
- Sample Size: A total of 457 S. aureus samples were evaluated in the clinical performance study.
- Data Provenance: The study was a multicenter clinical study conducted in 2009 at three geographically-diverse laboratories. The analytical performance section also mentions bacterial strains obtained from the Network on Antimicrobial Resistance in Staphylococcus aureus (NARSA), American Type Culture Collection (ATCC), and a collection from the Department of Infectious Disease Epidemiology of the Imperial College in London, England. This indicates a mix of strains from reference collections and clinical isolates, and at least some data provenance from England in addition to the diverse US laboratories. The study appears to be retrospective in the sense that existing S. aureus samples were evaluated by the new device.
3. Number of Experts and Qualifications for Ground Truth
The document does not mention the use of experts to establish ground truth for the test set.
4. Adjudication Method for the Test Set
The document does not mention an adjudication method for the test set.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. The study compares the device's performance to a standard method (cefoxitin disk diffusion), not to human readers' performance with and without AI assistance.
6. Standalone Performance Study
Yes, a standalone study was done. The clinical performance study directly evaluated the performance of the Clearview® Exact PBP2a Test against the reference method without human intervention in the interpretation of the device's results, as it is a visual read test that relies on the device's output. The reproducibility study also tested the device in a standalone manner.
7. Type of Ground Truth Used
The ground truth used for the clinical performance study was cefoxitin (30 ug) disk diffusion, interpreted according to CLSI (Clinical and Laboratory Standards Institute) standards. This is a recognized phenotypic method for determining methicillin resistance in S. aureus.
8. Sample Size for the Training Set
The document does not explicitly mention a dedicated "training set" or its size for the development of the Clearview® Exact PBP2a Test. The analytical performance section mentions that 162 MRSA strains and 112 MSSA strains were tested for analytical reactivity and specificity, which might represent samples used during later stages of development or validation, but it's not explicitly labeled as a training set.
9. How Ground Truth for the Training Set Was Established
Since a distinct training set is not explicitly defined, the method for establishing its ground truth is not detailed. However, for the strains used in analytical performance (162 MRSA and 112 MSSA), it is implied that their methicillin-resistant/sensitive status was known, likely established through standard microbiological identification and susceptibility testing methods (e.g., CLSI guidelines, reference lab testing) given their origin from reputable collections (NARSA, ATCC, Imperial College).
§ 866.1640 Antimicrobial susceptibility test powder.
(a)
Identification. An antimicrobial susceptibility test powder is a device that consists of an antimicrobial drug powder packaged in vials in specified amounts and intended for use in clinical laboratories for determining in vitro susceptibility of bacterial pathogens to these therapeutic agents. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.(b)
Classification. Class II (performance standards).