(64 days)
To determine bacterial antimicrobial agent susceptibility. The MicroScan® MICroSTREP plus™ Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of aerobic streptococci, including Streptococcus pneumoniae. After inoculation, panels are incubated for 20 - 24 hours at 35°C +/- 1°C in a non-CO2 incubator, and read visually according to the Package Insert. This particular submission is for the addition of the antimicrobial Erythromycin at concentrations of 0.015 to 2 mcg/ml to the test panel. The organisms which may be used for Erythromycin susceptibility testing in this panel are: Streptococcus pneumoniae, Streptococcus pyogenes, viridans group streptococci.
The MicroScan® MICroSTREP plus™ Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of aerobic streptococci, including Streptococcus pneumoniae. After inoculation, panels are incubated for 20 - 24 hours at 35°C +/- 1°C in a non-CO2 incubator, and read visually according to the Package Insert. The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test. Various antimicrobial agents are diluted in water. buffer or minute concentrations of broth to concentrations bridging the range of clinical interest. Panels are rehydrated with 115 ul Mueller-Hinton broth supplemented with 2-5% brsed horse blood (LHB) and buffered with 50 mM HEPES, after inoculation of the broth with a standardized suspension of the organism in saline. After incubation in a non-COincubator for 20-24 hours, the minimum inhibitory concentration (MIC) for the test organism is manually read by observing the lowest antimicrobial concentration showing inhibition of growth.
Here's a summary of the acceptance criteria and the study that proves the device meets them, based on the provided text:
Device: MicroScan® MICroSTREP plus™ Panel with Erythromycin
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Overall Essential Agreement with NCCLS frozen Reference panel for Erythromycin | 94.5% Essential Agreement |
| Acceptable Reproducibility and Precision with Erythromycin | Demonstrated acceptable reproducibility and precision |
| Acceptable Quality Control results for Erythromycin | Demonstrated acceptable results |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: The text states "Efficacy isolates" and "Challenge strains" were used, but does not provide specific numbers for the test set.
- Data Provenance: The external evaluation was conducted using "fresh and stock Efficacy isolates and stock Challenge strains." The country of origin is not specified, but the evaluation was external. The study was conducted on already isolated and characterized strains, indicating a retrospective nature for the "stock" strains, and potentially prospective collection for "fresh" isolates.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The document does not specify the number of experts or their qualifications for establishing the ground truth. It refers to an "NCCLS frozen Reference Panel" as the comparator, implying that the reference method itself serves as the ground truth, rather than expert consensus on individual test cases.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method involving multiple readers. The comparison was made against an "NCCLS frozen Reference Panel," which implies a direct comparison of results from the device to the reference standard, not a human reader adjudication process.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not explicitly mentioned or described. The study focuses on the standalone performance of the device against a reference method, not on the improvement of human readers with AI assistance.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, a standalone study was performed. The device, the MicroScan® MICroSTREP plus™ Panel, is intended to be read visually by a human, but the performance comparison outlined (Essential Agreement against an NCCLS frozen Reference panel) is evaluating the inherent accuracy of the device's determination of MIC, not the human interpretation of the device's output or any AI assistance for visual reading. The context refers to the device and its output, which is then read by a person according to a package insert. The "algorithm" in this case is the chemical and biological reaction within the panel that produces the visible growth inhibition, and its performance is evaluated in a standalone manner against the reference.
7. Type of Ground Truth Used
The ground truth used was the results obtained from an NCCLS frozen Reference Panel. This is a recognized standard method for antimicrobial susceptibility testing.
8. Sample Size for the Training Set
The document does not explicitly mention a separate "training set" or its sample size. The description focuses on an "external evaluation" against a reference panel. Given that this is a chemical/biological test panel rather than an AI/machine learning algorithm that requires explicit training, the concept of a "training set" in the common sense (e.g., for model development) is not applicable here. The assay development itself would have involved extensive optimization, but this wouldn't be referred to as a "training set" in this context.
9. How the Ground Truth for the Training Set Was Established
As noted in point 8, a "training set" in the conventional sense is not applicable. The device's performance is inherently tied to its design and manufacturing. The "ground truth" for the performance evaluation was established by a recognized standard: the NCCLS frozen Reference Panel.
§ 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).