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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 Ampicillin, at concentrations of 0.03– 16 mcg/ml on the MicroScan MICroSTREP plus® Panel.

The organisms which may be used for Ampicillin susceptibility testing on this panel are:

Streptococcus spp. other than 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.

Here's an analysis of the provided text, focusing on the acceptance criteria and study information for the MicroScan MICroSTREP plus® Panel with Ampicillin:

Acceptance Criteria and Device Performance

The study presented in the 510(k) summary demonstrates that the MicroScan MICroSTREP plus® Panel for Ampicillin, when read by the MicroScan® WalkAway instrument, meets the acceptance criterion of 94.3% overall Essential Agreement. Reproducibility and Quality Control also met acceptable standards.

Study Details

2. Sample size used for the test set and the data provenance:

• Test Set Sample Size: Not explicitly stated in terms of an exact number of isolates. However, the external evaluation was conducted with "stock and CDC Challenge strains."
• Data Provenance: Not explicitly stated, but the mention of "CDC Challenge strains" suggests a U.S. context. The study appears to be prospective in nature, as it was designed 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 specified.
• Qualifications of Experts: Not specified.

4. Adjudication method for the test set:

• The ground truth (referred to as "Expected Result") was established based on a "CLSI frozen Reference Panel." This suggests a standardized, consensus-driven process based on clinical and laboratory standards, rather than individual expert adjudication.

5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done:

• No, an MRMC comparative effectiveness study was not explicitly mentioned. The study compares instrument readings to a predetermined "Expected Result" from a reference panel, not to human readers' performance.

6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:

• Yes, this was a standalone study. The performance of the MicroScan® WalkAway instrument (algorithm only) was evaluated in reading the MICroSTREP plus® Panel for Ampicillin. No human-in-the-loop performance was evaluated as part of this submission.

7. The type of ground truth used:

• Ground Truth Type: "Expected Result generated on a CLSI frozen Reference Panel." This represents a standardized, expert-derived, and validated reference standard, likely based on established microbiological methods.

8. The sample size for the training set:

• Not applicable/Not explicitly mentioned. This document describes an evaluation study for a device reading, not the development or training of an AI algorithm in the contemporary sense. The "training" of the instrument reader would have been part of its initial design and validation, prior to this specific submission.

9. How the ground truth for the training set was established:

• Not applicable/Not explicitly mentioned in this document. The focus of this 510(k) submission is on the performance of the instrument for reading Ampicillin on an existing panel, using a specific reference method as the ground truth for evaluation.

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