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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 Meropenem, at concentrations of 0.03 to 4 mcg/ml on the MicroScan MICroSTREP plus® Panel.

The organisms which may be used for Meropenem susceptibility testing in this panel are:

Streptoccus pneumoniae (excluding penicillin-resistant strains) 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℃ +/-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.

Acceptance Criteria and Device Performance Study for MicroScan MICroSTREP plus® Panel (Meropenem)

This document describes the acceptance criteria and the study conducted to demonstrate the substantial equivalence of the MicroScan MICroSTREP plus® Panel with Meropenem, specifically for instrument-read results using the MicroScan® WalkAway instrument.

1. Table of Acceptance Criteria and Reported Device Performance

Note: The acceptance criteria for Essential Agreement (≥ 90%) is derived from the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (February 5, 2003), which is referenced in the 510(k) summary.

2. Sample Size and Data Provenance for the Test Set

• Sample Size: The document does not explicitly state the exact number of isolates or tests performed in the evaluation for Essential Agreement. However, it mentions the evaluation was conducted with "stock and CDC Challenge strains."
• Data Provenance: The data provenance is not explicitly stated in terms of country of origin but is implied to be from Dade Behring Inc. (USA) as the manufacturer. The study is prospective as it involves evaluations designed to confirm acceptability against pre-determined Expected Results.

3. Number and Qualifications of Experts for Ground Truth

The document does not mention the use of human experts to establish ground truth for the test set.

4. Adjudication Method for the Test Set

No adjudication method is described, as the ground truth was established by a reference method rather than expert consensus.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No MRMC comparative effectiveness study was conducted. This study focused on the performance of the instrument-read method compared to a reference standard, not on human reader performance with or without AI assistance.

6. Standalone Performance Study

Yes, a standalone performance study was done. The study evaluated the performance of the algorithm only (MicroScan® WalkAway instrument read method) without human intervention or human-in-the-loop performance, by comparing its results to an established reference method.

7. Type of Ground Truth Used for the Test Set

The ground truth used was an expected result generated on a CLSI frozen Reference Panel. This represents a recognized standard for determining antimicrobial susceptibility, aligning with established laboratory methods.

8. Sample Size for the Training Set

The document does not explicitly mention a separate "training set" or its sample size. The evaluation was framed as a comparison against an "Expected Result" from a reference panel, which suggests a validation study rather than a machine learning training process with a distinct training set. If the MicroScan WalkAway instrument uses an algorithm that was previously developed and trained, the details of that training are not provided in this submission.

9. How Ground Truth for the Training Set Was Established

As noted in section 8, a separate training set is not explicitly discussed. For the purpose of the evaluation, the "Expected Results" for comparison were determined before the evaluation, using a CLSI frozen Reference Panel. This implies that the reference panel served as the gold standard for defining correct susceptibility results against which the instrument's performance was measured.

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