(51 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. Additionally, the panels may be incubated in and read by a MicroScan ® WalkAway instrument.
This particular submission is for the addition of instrument read capability of the antimicrobial Trimethoprim/Sulfamethoxazole, at concentrations of 0.06/1.15 to 8/152 mcg/ml on the MicroScan MICroSTREP plus® Panel.
The organisms which may be used for Trimethoprim/Sulfamethoxazole susceptibility testing on this panel are:
Streptococcus pneumoniae
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 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 µl Mueller-Hinton broth supplemented with 2-5% lysed 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-CO2 incubator 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. Additionally, the panels may be incubated in and read by a MicroScan® WalkAway instrument.
Here's an analysis of the provided text, outlining the acceptance criteria and study details for the MicroScan MICroSTREP plus® Panel with Trimethoprim/Sulfamethoxazole instrument read capability:
1. Table of Acceptance Criteria and Reported Device Performance:
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Overall Essential Agreement with Expected Result | 100% for Trimethoprim/Sulfamethoxazole instrument read results |
| Instrument reproducibility | Demonstrated acceptable reproducibility and precision |
| Quality Control testing | Demonstrated acceptable results |
2. Sample size used for the test set and the data provenance:
- Sample size: Not explicitly stated. The document mentions "stock and CDC Challenge strains" were used for external evaluation.
- Data Provenance: The strains were "stock and CDC Challenge strains," suggesting they are well-characterized, potentially from reference collections. The country of origin is not specified, but CDC generally refers to the U.S. Centers for Disease Control and Prevention. The study appears to be a prospective evaluation based on its design to "confirm the acceptability of the proposed instrument read method" by comparing its performance with "Expected Results determined before the evaluation."
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- Number of experts: Not explicitly stated.
- Qualifications of experts: Not explicitly stated. The ground truth ("Expected Results") was based on a "CLSI frozen Reference Panel," implying that the standard for establishing these results would follow CLSI (Clinical and Laboratory Standards Institute) guidelines, which are established by expert consensus in microbiology.
4. Adjudication method for the test set:
- The document implies a direct comparison of the instrument read results to the "Expected Results" from the CLSI frozen Reference Panel. There is no mention of a traditional expert adjudication process (e.g., 2+1, 3+1) as one might find in image-based diagnostic studies. The "Expected Results" themselves serve as the adjudicated ground truth.
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 explicitly done. This study focuses on validating the performance of an instrument read method compared to a reference standard, not on comparing human readers with and without AI assistance. The previous method was a "manual read" by observing the lowest antimicrobial concentration showing inhibition of growth. The new method is an "instrument read." The study aims to show the instrument read method is substantially equivalent to the expected results, not necessarily that it improves human reader performance or replaces human readers directly.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, a standalone study was done. The "instrument read method" assesses the performance of the MicroScan WalkAway instrument in interpreting the susceptibility panels. This is an algorithm-only evaluation where the instrument provides the result without direct human intervention in the interpretation phase for the test strains. The output is directly compared to the "Expected Result."
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The ground truth used was based on expert consensus embodied in a standardized reference method. Specifically, the "Expected Results" were generated on a CLSI frozen Reference Panel, which represents the gold standard for antimicrobial susceptibility testing, established and validated through extensive expert consensus within the CLSI framework.
8. The sample size for the training set:
- Not explicitly stated in the provided text. The document describes the external evaluation with "stock and CDC Challenge strains," which corresponds to the test set. Information on a separate training set for algorithm development is not included.
9. How the ground truth for the training set was established:
- Not applicable, as a separate training set and its ground truth establishment are not discussed in the provided text. The document focuses on the external validation of the instrument read method using a test set with pre-established "Expected Results" from a CLSI 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).