(17 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 Chloramphenicol, at concentrations of 1 to 32 mcg/ml on the MicroScan MICroSTREP plus ® Panel.
The organisms which may be used for Chloramphenicol susceptibility testing on this panel are: Susceptible streptococci, including 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 ul 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.
The provided text describes the 510(k) summary for the MicroScan MICroSTREP plus® Panel for determining bacterial susceptibility to Chloramphenicol using the MicroScan® WalkAway instrument.
Here's an analysis of the acceptance criteria and study information:
1. Table of Acceptance Criteria and Reported Device Performance:
| Acceptance Criteria (Set by FDA Guidance) | Reported Device Performance (Chloramphenicol) | Metric |
|---|---|---|
| "acceptable performance" (as defined in FDA guidance "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA", dated February 5, 2003) | 100% | Overall Essential Agreement |
| Acceptable reproducibility and precision | Acceptable | Instrument reproducibility |
| Acceptable results for Quality Control | Acceptable | Quality Control testing |
2. Sample Size Used for the Test Set and Data Provenance:
- Sample Size: Not explicitly stated as a single number. The study used "stock and CDC Challenge strains." The FDA guidance cited for AST systems would typically define the minimum number of isolates required for evaluation, but this specific number is not provided in the summary.
- Data Provenance: The study was an "external evaluation" conducted with "stock and CDC Challenge strains." This suggests a combination of curated and potentially geographically diverse strains, but specific countries of origin are not mentioned. The study appears to be prospective in the sense that the device was evaluated on these strains to confirm its performance against pre-established expected results.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications:
- Number of Experts: Not explicitly stated.
- Qualifications of Experts: Not explicitly stated. However, the ground truth was established by a "CLSI frozen Reference Panel," which implies that the "Expected Results" were determined by established, standardized methods and likely confirmed by expert microbiologists or reference laboratories adhering to Clinical and Laboratory Standards Institute (CLSI) guidelines.
4. Adjudication Method for the Test Set:
- The text describes comparing the instrument-read results "with an expected result generated on a CLSI frozen Reference Panel." This indicates a direct comparison to a pre-defined reference standard rather than an adjudication process between multiple human readers for the specific device test itself.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- No, a multi-reader multi-case (MRMC) comparative effectiveness study was not performed. The study focuses on evaluating the instrument's performance against a reference standard, not on comparing human reader performance with and without AI assistance.
6. Standalone (Algorithm Only) Performance:
- Yes, a standalone performance study was done. The entire premise of the submission is to demonstrate the performance of the MicroScan® WalkAway instrument (which automates the reading process) when determining susceptibility to Chloramphenicol on the MICroSTREP plus® Panel. The "Essential Agreement of 100% for Chloramphenicol instrument read results compared with the Expected Result" directly reflects the standalone performance of the instrument/algorithm.
7. Type of Ground Truth Used:
- Expert Consensus / Reference Standard: The ground truth was established as "Expected Results determined before the evaluation" using a "CLSI frozen Reference Panel." This implies that the expected MIC values were determined through recognized, standardized laboratory methods, likely involving expert consensus on the interpretation of those reference methods (e.g., broth microdilution or agar dilution as per CLSI guidelines).
8. Sample Size for the Training Set:
- The document does not specify a separate training set. This is a 510(k) submission for a device that uses an instrument to read pre-determined assays. The "instrument read method" performance is being evaluated, implying the instrument's reading capabilities were developed and validated prior to this submission. The text focuses on the test set performance to show equivalence. In older submissions for IVD devices, explicit training/validation splits with detailed sample sizes were not always outlined as they might be for modern AI/ML systems.
9. How the Ground Truth for the Training Set Was Established:
- As no separate training set is explicitly mentioned, the method for establishing ground truth for a training set is not provided. The development of the WalkAway instrument's reading algorithm would have involved its own internal validation and calibration processes, but these details are not part of this 510(k) summary. The "Expected Results" for the test set were based on the CLSI 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).