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VITEK® 2 Gram Negative Piperacillin is designed for antimicrobial susceptibility testing of gramnegative organisms 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 Gram Negative Piperacillin is a quantitative test. Piperacillin has been shown to be active against most strains of the organisms listed below according to the FDA label for the antirocrobial.

Active in vitro and in clinical infections

Acinetobacter species Enterobacter species Escherichia coli Klebsiella species

Morganella morganii Providencia rettgeri Proteus mirabilis Proteus vulgaris

Pseudomonas aeruginosa Serratia species

Active in vitro but their clinical significance is uknown: Burkholderia cepacia Citrobacter koseri (formerly C. diversus)

Citrobacter freundii Pseudomonas fluorescens

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 for the most clinically significant aerobic gram-negative bacilii, Staphylococcus spp., Enterococcus spp., Streptococcus agalactiae, and S. pneumoniae.

The VITEK 2 AST Cards are essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MC) 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.

Here's a breakdown of the acceptance criteria and study details for the VITEK® 2 Gram Negative Piperacillin device, based on the provided text:

Acceptance Criteria and Reported Device Performance

Study Details

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

   • Sample Size: Not explicitly stated as a number of isolates. The document mentions "fresh and stock clinical isolates and stock challenge strains."
   • Data Provenance: Not explicitly stated, but it was an "external evaluation," implying data was collected outside of bioMérieux's internal development environment. The country of origin is not specified. It included both "fresh and stock clinical isolates," indicating a mix of prospective and retrospective (archived) clinical data.

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

   • Not specified. The ground truth method (CLSI broth microdilution) is a standardized laboratory method rather than expert consensus on individual cases.

3. Adjudication Method for the Test Set:

   • Not applicable. The ground truth was established by the CLSI broth microdilution reference method, which is an objective measurement, not requiring human adjudication of differing interpretations.

4. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done:

   • No, an MRMC study was not done. This device is an automated in vitro diagnostic (IVD) system for antimicrobial susceptibility testing, not a device intended for direct human interpretation or improvement of human reader performance. The study compared the device's performance to a reference laboratory method.

5. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done:

   • Yes, this was a standalone performance study. The VITEK® 2 system is an automated device, and its performance was evaluated against the CLSI reference method to determine its accuracy without human intervention other than sample preparation and loading.

6. The Type of Ground Truth Used:

   • Expert Consensus: No
   • Pathology: No
   • Outcomes Data: No
   • Other: CLSI broth microdilution reference method. This is a universally accepted standardized laboratory procedure for determining minimum inhibitory concentrations (MICs) of antimicrobial agents.

7. The Sample Size for the Training Set:

   • Not applicable/Not mentioned. The document describes a validation study for a device. For a traditional in vitro diagnostic, the "training set" concept (as in machine learning) is generally not applied in the same way. The device's underlying methodology is based on established microbiological principles, and its performance is validated using a test set against a gold standard.

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

   • Not applicable/Not mentioned (see point 7).

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