(22 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 Cefuroxime, at concentrations of 0.12 to 8 mcg/ml on the MicroScan MICroSTREP plus® Panel. The organisms which may be used for Cefuroxime susceptibility testing in 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℃ +/-1ºC 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.
Here's an analysis of the provided information regarding the MicroScan MICroSTREP plus® Panel's acceptance criteria and the study proving its performance:
Acceptance Criteria and Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Overall Essential Agreement for Cefuroxime instrument read results compared with Expected Result | 98.1% |
| Reproducibility and Precision for Vancomycin and WalkAway instrument | Demonstrated acceptable reproducibility and precision |
| Quality Control Testing for Cefuroxime | Demonstrated acceptable results |
Study Details
-
Sample Size used for the test set and data provenance:
- The document mentions "external evaluations" conducted with "stock and CDC Challenge strains." However, the exact sample size for the test set (number of unique isolates) is not explicitly stated.
- The data provenance is from in vitro testing using laboratory strains ("stock and CDC Challenge strains"), implying a controlled, laboratory-based study. The country of origin is not specified but given the FDA submission, it's likely primarily US-based or compliant with US standards. The study appears to be prospective for the device's performance evaluation against the established "Expected Result."
-
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The document implies that the ground truth, referred to as the "Expected Result," was generated on a CLSI frozen Reference Panel. This suggests the ground truth was established by a standardized, validated method (CLSI reference method), rather than by individual human experts per se. It doesn't specify the number or qualifications of experts involved in the initial CLSI reference panel validation or the generation of the "Expected Result" for this specific study.
-
Adjudication method for the test set:
- The document states that the "external evaluations were designed to confirm the acceptability of the proposed instrument read method... by comparing its performance with Expected Results determined before the evaluation." This indicates a direct comparison to a pre-defined reference standard. There is no mention of an adjudication method as typically understood for human reader discrepancies (e.g., 2+1 or 3+1). The "Expected Result" serves as the single, authoritative ground truth.
-
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 study focuses on the standalone performance of an instrument-read method for antimicrobial susceptibility testing, comparing it to a reference method. It does not involve human readers or AI assistance in the context of an MRMC study.
-
If a standalone (i.e. algorithm only without human-in-the loop performance) was done:
- Yes, a standalone study was done. The study evaluates the "proposed instrument read method" (MicroScan® WalkAway instrument) for the MICroSTREP plus® Panel. This is a standalone evaluation of the device without human intervention in the reading process, comparing it to an "expected result."
-
The type of ground truth used:
- The ground truth used was based on an "expected result generated on a CLSI frozen Reference Panel." This is a highly standardized, reference method ground truth (broth dilution method as miniaturized for the panels) which is widely accepted in microbiology for antimicrobial susceptibility testing.
-
The sample size for the training set:
- The document pertains to the evaluation of an instrument-read method for an existing panel. There is no mention of a separate "training set" for an algorithm in the traditional machine learning sense. The "MicroScan MICroSTREP plus® Panel" itself is a product; the evaluation is about adding "instrument read capability" for a specific antimicrobial (Cefuroxime). If the WalkAway instrument's reading mechanism involved an algorithm that required training, those details are not provided in this 510(k) summary. The study is an evaluation of the instrument's performance, not the development of a new algorithm.
-
How the ground truth for the training set was established:
- Since there's no explicit training set mentioned in the context of algorithm development, the method for establishing its ground truth is not applicable or detailed here. The "Expected Results" for the test set were established using 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).