(152 days)
The MicroScan® Dried Gram-Positive MIC/Combo Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-positive cocci. After inoculation, panels are incubated for 16 - 24 hours at 35℃ +/- 1℃ in a non-CO2 incubator, and read either visually or with MicroScan instrumentation, according to the Package Insert.
The MicroScan Cefoxitin Screen is intended to determine the susceptibility of staphylococci to the penicillinase stable beta-lactams.
This particular submission is for the addition of the antimicrobial test the Cefoxitin Screen, at a concentration of 4 mcg/ml, to the test panel.
The gram-positive organisms which may be used for Cefoxitin Screen susceptibility testing in this panel are:
Staphylococcus aureus Staphylococcus lugdunensis
MicroScan Dried Gram-Positive MIC/Combo Panels are designed for use in determining quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-positive cocci.
The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in broth and dehydrated. Various antimicrobial agents are diluted in broth to concentrations bridging the range of clinical interest. Panels are rehydrated with water after inoculation with a standardized suspension of the organism. After incubation in a non-CO2 incubator for 16-20 hours, the minimum inhibitory concentration (MIC) for the test organism is read by determining the lowest antimicrobial concentration showing inhibition of growth.
Here's a breakdown of the acceptance criteria and study information based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Categorical Agreement vs. CLSI Cefoxitin Disk Diffusion | High (e.g., >90%) | 97.8% |
| Categorical Agreement vs. mecA PCR | High (e.g., >90%) | 98.7% |
| Sensitivity vs. CLSI Cefoxitin Disk Diffusion | High (e.g., >90%) | 98.6% |
| Specificity vs. CLSI Cefoxitin Disk Diffusion | High (e.g., >90%) | 96.9% |
| Sensitivity vs. mecA PCR | High (e.g., >90%) | 99.7% |
| Specificity vs. mecA PCR | High (e.g., >90%) | 97.7% |
| Reproducibility (Inoculum and Instrument) | Acceptable reproducibility and precision | Demonstrated acceptable reproducibility and precision |
| Quality Control | Acceptable results for Cefoxitin Screen Well | Demonstrated acceptable results |
Note: The document explicitly states the device's performance metrics but implies the acceptance criteria by stating that the "Cefoxitin Screen demonstrated acceptable performance" when compared to the reference methods and that its performance was "substantially equivalent" as defined by FDA guidance documents. Exact numerical acceptance thresholds are not provided in this summary.
2. Sample Size Used for the Test Set and Data Provenance
The document refers to "external design validation (Clinical Trial) was conducted with fresh and stock Efficacy isolates and stock Challenge strains." However, the specific sample size for the test set is not provided.
Regarding data provenance:
- Country of Origin: Not specified.
- Retrospective or Prospective: The use of "fresh and stock Efficacy isolates and stock Challenge strains" suggests a combination. "Fresh" isolates could imply prospective collection, while "stock" isolates typically refer to retrospective or archived samples.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
This information is not provided in the summary. The ground truth was established by comparing the device's performance against two reference methods (CLSI cefoxitin disk diffusion and mecA PCR) and to "Expected Results" for challenge strains, but it doesn't mention expert review of the test set itself.
4. Adjudication Method for the Test Set
This information is not provided in the summary. The ground truth was established by reference methods and expected results, not through an explicit adjudication process described in the text.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
A MRMC comparative effectiveness study was not performed according to this summary. The study is evaluating the performance of an automated susceptibility test system against reference methods, not human readers.
6. Standalone (i.e. algorithm only without human-in-the loop performance) Study
Yes, a standalone study was performed. The "MicroScan® Dried Gram-Positive MIC/Combo Panels" is an automated system designed for determining antimicrobial susceptibility. Its performance was evaluated directly against reference standards (CLSI cefoxitin disk diffusion and mecA PCR) and against "Expected Results" for challenge strains, indicating an algorithm-only evaluation without human-in-the-loop performance being part of this PAI.
7. Type of Ground Truth Used
The ground truth was established primarily using:
- Reference Methods: CLSI cefoxitin disk diffusion test.
- Molecular Test: mecA PCR.
- Expected Results: For stock Challenge strains, determined prior to evaluation.
8. Sample Size for the Training Set
The sample size for the training set is not explicitly provided in the summary. The summary describes the test set and evaluation but does not detail the training process or dataset.
9. How the Ground Truth for the Training Set Was Established
This information is not provided in the summary. As the training set size isn't mentioned, the method for establishing its ground truth is also absent.
§ 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).