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The VITEK® 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK® 2 and VITEK® 2 Compact Systems for the automated quantitative or qualitative determination of the susceptibility of most clinically significant aerobic gram-positive cocci including Staphylococcus spp., Enterococcus spp., Streptococcus agalactiae, and S. pneumoniae.

VITEK 2 Gram Positive Ertapenem for Streptococcus pneumoniae is designed for antimicrobial susceptibility testing of Streptococcus pneumoniae. It 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.

The VITEK 2 AST Cards are essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) microdilution methodology. The bacterial isolate to be tested is diluted to a standardized concentration in 0.45% saline before being used to rehydrate the antimicrobial medium within the card. The VITEK 2 System 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 antibiotic contained on the card.

VITEK® 2 Gram Positive Ertapenem for Streptococcus pneumoniae Acceptance Criteria Study Summary

This document summarizes the acceptance criteria and the study proving the device meets these criteria for the VITEK® 2 Gram Positive Ertapenem for Streptococcus pneumoniae.

1. Table of Acceptance Criteria and Reported Device Performance

Note: The FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA, Issued Feb. 5, 2003, typically sets benchmarks for category agreement in AST devices for substantial equivalence.

2. Sample Size Used for the Test Set and Data Provenance

• Test Set Sample Size: Not explicitly stated as a single number. The study utilized "fresh and stock clinical isolates and stock challenge strains."
• Data Provenance: The external evaluation was designed to confirm acceptability, suggesting data was collected specifically for this submission. The origin of the clinical isolates (e.g., country) is not specified. The study is prospective in the sense that it was conducted to compare the VITEK 2 device against a reference method.

3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications

• Number of Experts: Not applicable. The ground truth was established by a reference laboratory method, not by expert interpretation.
• Qualifications of Experts: Not applicable.

4. Adjudication Method for the Test Set

• Adjudication Method: Not applicable. The "CLSI (NCCLS) microbroth dilution reference method" was used as the gold standard for ground truth. This method itself establishes results, rather than requiring expert adjudication of interpretations.

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

• MRMC Study Done? No. This device is an automated antimicrobial susceptibility test system. Its performance is compared against a reference laboratory method, not against human readers. Therefore, an MRMC study and analysis of human reader improvement with AI assistance is not relevant or presented.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

• Standalone Study Done? Yes. The study evaluated the VITEK® 2 system's performance (which is an automated algorithm) directly against the CLSI (NCCLS) reference method. This is effectively a standalone performance evaluation of the device.

7. Type of Ground Truth Used

• Type of Ground Truth: The ground truth was established by the CLSI (NCCLS) microbroth dilution reference method. This is a recognized laboratory standard for determining minimum inhibitory concentrations (MICs) of antimicrobials.

8. Sample Size for the Training Set

• Training Set Sample Size: Not explicitly mentioned. For AST devices, the "training" (or development) process involves establishing the algorithms and interpretive criteria for the VITEK 2 system based on extensive historical data and correlation studies between growth patterns and known MICs. The specific dataset used for this initial development is not detailed in this submission. The external evaluation uses "fresh and stock clinical isolates and stock challenge strains" which serve as a validation set.

9. How the Ground Truth for the Training Set Was Established

• Ground Truth for Training Set: The submission does not detail the specific ground truth establishment for a "training set." However, it can be inferred that the VITEK 2 system's underlying algorithms and interpretive rules would have been developed and validated against a large body of data where MICs were determined by established reference methods (like CLSI microbroth dilution) for various microorganisms and antimicrobials. This iterative process allows the system to learn and correlate growth patterns detected by the VITEK 2 with known antimicrobial susceptibility results from reference methods.

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