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VITEK® 2 Streptococcus Trimethoprim / Sulfamethoxazole is designed for antimicrobial susceptibility testing of Streptococcus species. VITEK® 2 Streptococcus Trimethoprim / Sulfamethoxazole is a qualitative test 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.

Trimethoprim and Sulfamethoxazole have been shown to be active against most strains of the following microorganism, according to the FDA label for this antimicrobial.

Active In Vitro and in Clinical Infections against:

Streptococcus pneumoniae

The VITEK® 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK® 2 System 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 with 0,45% to 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, sealing and loading operation. The VITEK® 2 Systems monitor the growth of each well in the card over a defined period of time (up to 36 hours for yeast). At the completion cycle, a report is generated that contains the MIC value along with the interpretive category result for each antimicrobial contained on the card.

Acceptance Criteria and Study for VITEK® 2 AST-ST Trimethoprim / Sulfamethoxazole

This report summarizes the acceptance criteria and the study conducted to prove the VITEK® 2 AST-ST Trimethoprim / Sulfamethoxazole device meets these criteria, based on the provided text.

1. Table of Acceptance Criteria and Reported Device Performance

Note: The specific numerical acceptance criteria for "Reproducibility" and "Quality Control" are not explicitly stated in the provided text, only that the results were "acceptable."

2. Sample Size and Data Provenance

• Test Set Sample Size: Not explicitly stated as a single number. The study used "fresh and stock clinical isolates, as well as a set of challenge strains." The exact number of each type of isolate is not provided.
• Data Provenance: The text does not specify the country of origin for the clinical isolates. It refers to "external evaluation," suggesting data collected from external sites. The study was retrospective, using "fresh and stock clinical isolates" that were pre-existing.

3. Number of Experts and Qualifications for Ground Truth

The provided text does not mention the use of human experts to establish ground truth for the test set. The ground truth was established by a reference method.

4. Adjudication Method for the Test Set

The provided text does not mention an adjudication method involving experts. The comparison was directly to a reference method.

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

An MRMC comparative effectiveness study was not performed. This device is an automated, standalone diagnostic system for antimicrobial susceptibility testing, not designed to assist human readers in interpretation.

6. Standalone Performance

Yes, a standalone performance study was done. The VITEK® 2 AST-ST Trimethoprim / Sulfamethoxazole device's performance was compared directly against the CLSI broth microdilution reference method, which represents the algorithm's performance without human intervention in the interpretation phase beyond loading and starting the system.

7. Type of Ground Truth Used

The ground truth used was the CLSI broth microdilution reference method. This is a laboratory-based, internationally recognized standard method for determining minimum inhibitory concentrations (MICs) of antimicrobials.

8. Sample Size for the Training Set

The provided text does not specify a separate training set sample size. The study describes an "external evaluation" where performance was compared to a reference method. For a device like VITEK® 2, the development and internal validation (which might involve data analogous to a training set) would likely occur prior to the external evaluation described for regulatory submission. However, details of any specific training set are not provided in this summary.

9. How Ground Truth for the Training Set Was Established

As no specific training set is mentioned, the method for establishing its ground truth is also not provided. It is assumed that any internal development or training would also rely on established reference methods like CLSI broth microdilution.

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