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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 susceptibility testing of isolated colonies of clinically significant aerobic gram positive bacteria. VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole is designed for Trimethoprim/sulfamethoxazole susceptibility testing of Staphylococcus aureus, Enterococcus species, and Streptococcus species including Streptococcus agalactiae, and S. pneumoniae. VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole is a qualitative test. 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.

VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole is designed for antimicrobial susceptbility since with the VITEK® 2 and VITEK® 2 and VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. The antimicrobial presented in VITEK 2 AST Cards is in concentrations equivalent by efficacy to r he unlinerebial procentrations in mcg/mi. 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 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.

Here's an analysis of the provided text, focusing on the acceptance criteria and the study details for the VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole device:

Acceptance Criteria and Device Performance for VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document implicitly defines acceptable results for reproducibility and quality control by stating they were "acceptable." Specific quantitative thresholds for these metrics are not provided in the excerpt.

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

The document states that the evaluation was conducted with fresh and stock clinical isolates and stock challenge strains. However, it does not provide a specific sample size (number of isolates/strains) used for the external evaluations (test set).

The data provenance is retrospective and prospective, as it includes both clinical isolates (which can be retrospective or freshly collected) and stock challenge strains. The country of origin of the data is not explicitly stated, but the submitter (bioMérieux, Inc.) is based in the USA, and the FDA is the regulatory body, suggesting the data is likely from the USA or was submitted for approval in the USA.

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

The document does not explicitly state the number of experts used or their qualifications. The "NCCLS reference macrobroth dilution method" is the ground truth, which is a standardized laboratory procedure, not typically established by individual experts but rather by a consensus of scientific bodies (e.g., Clinical and Laboratory Standards Institute, formerly NCCLS). The performance of this reference method would be carried out by trained laboratory personnel, but they are not categorized as "experts" in the context of establishing ground truth in the same way, for example, a radiologist interprets an image.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method for the test set. The ground truth is established by the "NCCLS reference macrobroth dilution method," which is a direct comparative method rather than an interpretive classification requiring adjudication of multiple readings.

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

No MRMC comparative effectiveness study was done as described in the provided text. This study is focused on the device's performance against a reference method, not on how human readers improve with or without AI assistance.

6. Standalone (Algorithm Only) Performance Study

Yes, a standalone performance study was done. The entire evaluation described is a standalone study, comparing the device (VITEK® 2 system) directly to the NCCLS reference macrobroth dilution method. The VITEK® 2 system's performance is reported (99.6% overall Category Agreement) without human interpretation in the results. The system automatically processes the cards and generates a report.

7. Type of Ground Truth Used

The type of ground truth used is the NCCLS reference macrobroth dilution method. This is a laboratory-based, gold-standard method for determining antimicrobial susceptibility, providing quantitative Minimum Inhibitory Concentration (MIC) values and interpretive categories.

8. Sample Size for the Training Set

The document does not specify a sample size for the training set. The provided text focuses on the performance evaluation (validation) of the device against a reference method. It's common for such submissions to describe the validation data rather than the internal development/training data, especially for hardware-based systems like the VITEK 2.

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

The document does not provide information on how the ground truth for the training set was established. This detail would typically be part of the device's internal development process and is not included in this 510(k) summary, which focuses on the validation of the final product. Assuming a similar development process, it is likely that reference methods similar to the NCCLS macrobroth dilution method were used during training and development phases.

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