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VITEK 2 Streptococcus Meropenem is designed for antimicrobial susceptibility testing of Streptococcus species and is intended for use with the VITEK® 2 and VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK® 2 Streptococcus Meropenem is a quantitative test. Meropenem has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active in vitro and in clinical infections Streptococcus pneumoniae (penicillin-susceptible strains) Streptococcus agalactiae Streptococcus pyogenes

The VITEK® 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK® 2 Systems for the automated quantitative or qualitative susceptibility testing of isolated colonies for the most clinically significant aerobic gram-negative bacilli, Staphylococcus spp., Enterococcus spp. Streptococcus spp. and clinically significant yeast.

The VITEK® 2 AST Cards are essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) microdilution methodology.

The isolate to be tested is diluted to a standardized concentration in 0.45 - 0.50% saline before being used to rehydrate the antimicrobial medium within the card. The VITEK® 2 automatically fills, seals and places the card into the incubator/reader. The VITEK® 2 Compact has a manual filling and sealing operation. The VITEK® 2 monitors the growth of each well in the card over a defined period of time (up to 18 hours). At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result for each antimicrobial contained on the card.

Here's a breakdown of the acceptance criteria and study information for the VITEK® 2 AST-ST Meropenem device, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

Note: The specific numerical acceptance criteria (e.g., minimum percentage for essential and category agreement) are not explicitly stated in the provided text. However, "substantially equivalent performance" is mentioned, and the reported results are described as demonstrating "acceptable performance" compared to the CLSI broth microdilution reference method, which serves as the benchmark.

2. Sample Size and Data Provenance for the Test Set

• Sample Size: Not explicitly stated as a numerical value for the entire test set. The text mentions "fresh and stock clinical isolates, as well as a set of challenge strains." This suggests a varied and potentially large sample, but a concrete number is not provided.
• Data Provenance: Not explicitly stated (e.g., country of origin). The isolates are described as "fresh and stock clinical isolates," implying they were derived from actual patient samples, and "challenge strains." The study was an "external evaluation," which typically means it was conducted independently or at multiple sites. It does not specify if the data was retrospective or prospective, but given the nature of AST, it's likely a mix, with clinical isolates being pre-existing (retrospective) and challenge strains potentially being specifically prepared for the study.

3. Number of Experts and Qualifications for Establishing Ground Truth (Test Set)

This information is not provided in the text. Antimicrobial Susceptibility Testing (AST) systems typically establish ground truth by comparing to a gold standard method (like CLSI broth microdilution), not usually through expert consensus on individual interpretative calls.

4. Adjudication Method (Test Set)

This information is not provided and is generally not applicable to AST systems where the ground truth is established by a reference laboratory method rather than human interpretation requiring adjudication.

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

This was not done. MRMC studies are relevant for medical imaging devices where human readers interpret images and their performance is compared with and without AI assistance. This device is an automated antimicrobial susceptibility testing system, not an imaging device.

6. Standalone Performance Study

Yes, a standalone study was done. The VITEK® 2 AST-ST Meropenem device's performance was compared directly to the CLSI broth microdilution reference method. The reported Essential Agreement (98.6%) and Category Agreement (96.6%) reflect the algorithm's (device's) performance without human-in-the-loop modifications to its results. The device "automatically fills, seals and places the card into the incubator/reader" and "monitors the growth of each well... At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result." This describes an automated, standalone process.

7. Type of Ground Truth Used

The ground truth used was the CLSI broth microdilution reference method. This is considered the gold standard for antimicrobial susceptibility testing.

8. Sample Size for the Training Set

The document does not provide specific details about a 'training set' sample size. While the initial development of such a system would involve extensive data for model building, the K132507 submission focuses on the validation study comparing the finalized device to the reference method.

9. How Ground Truth for the Training Set Was Established

The document does not provide this information. Similar to point 8, the focus is on the validation study. However, for AST systems, ground truth for training data would also typically be established using a recognized reference method like CLSI broth microdilution.

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