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VITEK® 2 Gram Negative Ertapenem is designed for antimicrobial susceptbility testing of Gram negative bacilli and is intended for use with the VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK® 2 Gram Negative Ertapenem is a quantitative test. Ertapenem 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: Escherichia coli Klebsiella pneumoniae Proteus mirabilis

In vitro data available but clinical significance is unknown: Citrobacter freundii Citrobacter koseri Enterobacter aerogenes Enterobacter cloacae Klebsiella oxytoca (excluding ESBL producing isolates) Morganella morganii Proteus vulgaris Providencia rettgeri Providencia stuartii Serratia marcescens

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, Staphylococus 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.

The VITEK® 2 AST-Gram Negative Ertapenem device is designed for antimicrobial susceptibility testing of Gram-negative bacilli. The study assessed the device's performance against the CLSI broth microdilution reference method.

1. Table of Acceptance Criteria and Reported Device Performance:

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

The document states that an "external evaluation was conducted with fresh and stock clinical isolates, as well as a set of challenge strains." However, the exact sample size for the test set is not explicitly provided in the available text.

The data provenance is not specified regarding the country of origin. The test set included both "fresh and stock clinical isolates" and "challenge strains," indicating a mix of real-world isolates and potentially laboratory-prepared strains. The retrospective or prospective nature of the clinical isolate collection is not detailed.

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

This information is not provided in the document. The ground truth was established by the CLSI broth microdilution reference method, which is a standardized laboratory procedure, not typically an expert consensus process in the same way as, for example, image interpretation.

4. Adjudication Method for the Test Set:

Not applicable. The ground truth was established by the CLSI broth microdilution reference method, which is a direct comparative measurement against a standardized method, not a subjective interpretation requiring adjudication.

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

No. This type of study (MRMC) is typically relevant for interpretative devices where human readers are involved in the diagnostic process. The VITEK® 2 AST system is an automated quantitative testing device, and its performance is compared to a reference laboratory method rather than human interpretation.

6. Standalone Performance (Algorithm Only without Human-in-the-Loop Performance):

Yes, the study describes the standalone performance of the VITEK® 2 AST-GN Ertapenem device. The device's output (MIC value and interpretive category) was directly compared against the CLSI broth microdilution reference method. The VITEK® 2 systems "automatically fills, seals and places the card into the incubator/reader" and "monitors the growth of each well in the card over a defined period of time (up to 18 hours)," after which "a report is generated." This indicates an automated, standalone performance evaluation.

7. Type of Ground Truth Used:

The ground truth used was the CLSI broth microdilution reference method, incubated at 16-20 hours. This is a standardized laboratory method for determining minimum inhibitory concentrations (MICs) of antimicrobial agents.

8. Sample Size for the Training Set:

The sample size for the training set is not explicitly provided in the available text. The document focuses on the external evaluation data as the basis for performance claims.

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

This information is not provided in the document. Given that the VITEK® 2 systems use a predefined methodology for determining MICs, training likely involves developing algorithms based on correlations with reference methods, but the specifics of how ground truth was established for a training set (if a distinct training set exists in the traditional machine learning sense) are not described. The document highlights the comparison to the CLSI broth microdilution reference method for the external evaluation, which serves as the validation of performance.

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