(102 days)
The MicroScan® Synergies plus™ 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 enterococci and staphylococci. After inoculation, panels are incubated for 4.5 - 18 hours at 35℃ +/- 1℃, in a WalkAway® SI, or equivalent, and read by the MicroScan® Instrumentation. Additionally, the panels may be incubated in a non-CO2 incubator and the Antimicrobial Susceptibility Testing (AST) portions can be read visually, according to the Package Insert.
This particular submission is for the addition of the antimicrobial Streptomycin Synergy Screen, at a concentration of 1000 ug/ml, for enterococci, to the test panel.
The gram-positive organisms which may be used for Streptomycin Synergy Screen susceptibility testing in this panel are:
Enterococcus species
MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels, utilizing both the MicroScan® Rapid Fluorogenic Identification and Dried Overnight Antimicrobial Susceptibility Testing (AST) technologies, 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 enterococci and staphylococci.
The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in water and dehydrated. 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 Synergies plus"" Pos Broth, after inoculation with a standardized suspension of the organism. After incubation in the WalkAway® SI, or equivalent, System, for 4.5 -18 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 for the MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels with Streptomycin Synergy Screen, based on the provided text:
Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Substantially equivalent performance compared to a frozen Reference Panel, as defined in the FDA document "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA', dated February 5, 2003. | Overall Categorical Agreement of 98.4% for Streptomycin Synergy Screen when compared with the frozen Reference panel. |
| Acceptable reproducibility and precision for Streptomycin Synergy Screen. | Demonstrated acceptable reproducibility and precision with Turbidity inoculum preparation method and the WalkAway® SI System or equivalent. |
| Acceptable Quality Control testing results for Streptomycin Synergy Screen. | Demonstrated acceptable results for Streptomycin Synergy Screen. |
Study Information
2. Sample size used for the test set and the data provenance:
- Test Set Description: The external validation was conducted with "fresh and stock Efficacy isolates and stock Challenge strains."
- Sample Size: The exact numerical sample size for the test set is not specified in the provided text.
- Data Provenance: The text does not explicitly state the country of origin. It indicates "external validation," which could imply data collected from various geographical locations or a specific external site. The study seems to be prospective in nature for the "fresh" isolates, and potentially retrospective for the "stock" isolates and challenge strains.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The text does not specify the number of experts or their qualifications used to establish the ground truth for the test set.
4. Adjudication method for the test set:
- The text does not describe any specific adjudication method used for the test set. It mentions "Challenge strains were compared to Expected Results determined prior to the evaluation," implying a pre-defined ground truth for these strains, but not an adjudication process for discrepancies.
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 was not done. This device (antimicrobial susceptibility test panel) is a diagnostic assay, not an AI-assisted reading tool for human interpretation of images or other complex data.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, it was a standalone performance study. The device is designed to provide quantitative and/or qualitative antimicrobial agent susceptibility directly by determining the lowest antimicrobial concentration showing inhibition of growth after incubation. While human intervention is involved in preparing the inoculum and reading (or setting up an instrument to read), the core performance measurement (Categorical Agreement) is against a reference method. The text mentions "the minimum inhibitory concentration (MIC) for the test organism is read by determining the lowest antimicrobial concentration showing inhibition of growth," and this reading can be done by the WalkAway® SI system or equivalent, indicating an automated or semi-automated standalone nature for the reading part.
7. The type of ground truth used:
- The ground truth was established by a frozen Reference Panel. For the challenge strains, "Expected Results" were determined prior to the evaluation, which would likely be derived from a validated reference method.
8. The sample size for the training set:
- The text does not mention a training set sample size. This type of device (a diagnostic panel) typically undergoes R&D and validation but not in the same "training set" manner as machine learning algorithms.
9. How the ground truth for the training set was established:
- As a training set is not explicitly mentioned or applicable in the traditional sense for this type of device, the method for establishing its ground truth is not described. The "frozen Reference Panel" is used for validation/testing, not for training.
§ 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).