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VITEK 2 Streptococcus Tigecycline 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 Tigecycline is a qualitative test. Tigecycline 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 isolates) Streptococcus anginosus grp. (includes S. anginosus, S. intermedius, and S. constellatus) Streptococcus agalactiae Streptococcus pyogenes

The VITER 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.

The medical device, VITEK® 2 AST-ST Tigecycline, a fully automated short-term incubation cycle antimicrobial susceptibility system, was evaluated for its performance.

1. Acceptance Criteria and Reported Device Performance:

2. Sample Size and Data Provenance:

The study encompassed fresh and stock clinical isolates, as well as a set of challenge strains. The specific sample size for fresh, stock, and challenge isolates is not explicitly detailed beyond "an external evaluation was conducted with fresh and stock clinical isolates, as well as a set of challenge strains." The data provenance (country of origin) is not provided, and the study was retrospective as it compared the device performance to an established reference method.

3. Number and Qualifications of Experts:

This information is not provided in the document. The study evaluates the performance of an automated susceptibility testing system against a reference method, not against human expert interpretation requiring a ground truth established by experts.

4. Adjudication Method:

Adjudication methods like 2+1 or 3+1 are not applicable here. The study compares the results of the VITEK® 2 AST-ST Tigecycline directly with the CLSI broth microdilution reference method.

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

A MRMC comparative effectiveness study was not conducted. This device is an automated system for antimicrobial susceptibility testing, not an imaging diagnostic tool that typically involves human readers.

6. Standalone Performance:

Yes, a standalone performance study was conducted. The VITEK® 2 AST-ST Tigecycline's performance was compared directly to the CLSI broth microdilution reference method without human-in-the-loop intervention.

7. Type of Ground Truth Used:

The ground truth was established using the CLSI broth microdilution reference method, which is a widely accepted laboratory standard for determining minimum inhibitory concentrations (MICs) of antimicrobials.

8. Sample Size for the Training Set:

The document does not explicitly state the sample size used for the training set. It mentions "an external evaluation was conducted," implying a test set, but no separation of a training set is detailed.

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

As the document does not explicitly detail a separate training set, the method for establishing ground truth for a training set is not provided. It is assumed that the development of the VITEK® 2 system itself would have involved extensive calibration and validation against reference methods during its initial design, but specifics for this particular submission are focused on the external evaluation/test set.

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