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VITEK® 2 Gram Positive Daptomycin is designed for antimicrobial susceptibility testing of Gram positive microorganisms 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 Positive Daptomycin is a quantitative test. Daptomycin has been shown to be active against the microorganisms listed below according to the FDA label for the antimicrobial.

Active in vitro and in clinical infections:

Enterococcus faecalis (vancomycin-susceptible strains only) Staphylococcus aureus (including methicillin-resistant strains)

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 gramneqative bacilli, 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 (MIC) microdilution methodology.

The bacterial 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 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 Positive Daptomycin device, based on the provided 510(k) summary:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in the provided text. However, the study aims to demonstrate "substantially equivalent performance" to the CLSI broth microdilution reference method, as defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA, Issued March 5, 2007.

The reported performance directly addresses the "Category Agreement" as a key metric for demonstrating substantial equivalence.

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

• Sample Size for Test Set: The exact numerical sample size for "fresh clinical isolates" and "stock challenge strains" is not provided. It is stated as "an external evaluation was conducted with fresh clinical isolates and stock challenge strains."
• Data Provenance: The data is described as an "external evaluation" using "fresh clinical isolates and stock challenge strains." This suggests a prospective collection of isolates, though the specific country of origin is not mentioned. Given bioMérieux's location in Missouri, USA, it's highly probable the isolates were collected in the United States.

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

This information is not provided in the summary. For Antimicrobial Susceptibility Test (AST) systems, the "ground truth" is typically established by a recognized reference method (like CLSI broth microdilution), rather than human experts adjudicating results. The CLSI method itself has established protocols for accuracy and reliability.

4. Adjudication Method for the Test Set

This information is not applicable/provided in the context of an AST device where the ground truth is established by a reference method (CLSI broth microdilution), rather than human consensus.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance

This is not applicable to this device. The VITEK® 2 system is an automated AST system that provides quantitative and interpretive results. It is not an AI-assisted diagnostic tool that human readers would interpret. Therefore, an MRMC study assessing human reader improvement with AI assistance is not relevant.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, this was a standalone performance study. The VITEK® 2 system is automated and its performance was directly compared to the CLSI broth microdilution reference method without human intervention during the test result generation by the VITEK® 2 system. The reported "98.4% overall Category Agreement" reflects the standalone performance of the device.

7. The Type of Ground Truth Used

The ground truth used was the CLSI broth microdilution reference method. This is the gold standard for antimicrobial susceptibility testing.

8. The Sample Size for the Training Set

This information is not provided in the summary. The VITEK® 2 system is a well-established automated diagnostic platform, and its underlying methodology for determining MICs is based on miniaturized doubling dilution techniques rather than machine learning models that require explicit "training sets" in the conventional sense. The "training" for such systems involves extensive development and validation against reference methods to ensure accuracy across a wide range of microorganisms and antimicrobial concentrations.

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

This information is not provided and is likely not applicable in the typical sense of machine learning training. The VITEK 2 system's operational principles are based on established microbiological methods (doubling dilution technique), not on a "training set" that requires external ground truth establishment. The development process for such a system would involve rigorous optimization and internal validation against the CLSI reference method to ensure its algorithms accurately determine MICs.

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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 agalactiae, and S. pneumoniae. VITEK 2 Gram Positive Daptomycin is designed for antimicrobial susceptibility testing of Enterococcus faecalis, Staphylococcus aureus, Streptococcus agalactiae, Enterococcus faecium, Staphylococcus epidermidis and Staphylococcus haemolyticus. VITEK 2 Gram Positive Daptomycin is a quantitative test. It is intended for use with the VITEK 2 System as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents.

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 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 based on the provided text for the VITEK® 2 Gram Positive Daptomycin device:

Acceptance Criteria and Device Performance

Note: The specific numerical acceptance thresholds are not explicitly stated in the provided text, but the reported performance values are presented as demonstrating "acceptable performance" and "substantially equivalent performance" when compared to the reference method, as defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA, Issued Feb. 5, 2003.

Study Details:

1. Sample size used for the test set and the data provenance:

   • Test Set Sample Size: Not explicitly stated as a numerical value. The study mentions "fresh and stock clinical isolates and stock challenge strains."
   • Data Provenance: Not explicitly stated (e.g., country of origin). The nature ("fresh and stock clinical isolates") suggests real-world patient samples, but the geographic origin is not specified. It was a prospective evaluation in the sense that the VITEK 2 was compared against a reference method in a controlled study design.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • Not applicable/Not mentioned. The ground truth was established by a recognized reference method, not by expert consensus.

3. Adjudication method for the test set:

   • Not applicable/Not mentioned. Adjudication by experts is not relevant when comparing a device to a defined reference standard method.

4. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

   • Not applicable. This device is an automated antimicrobial susceptibility testing system, not an AI-assisted diagnostic intended for human reader interpretation improvement. The comparison is between the automated system and a laboratory reference method.

5. If a standalone (i.e. 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 designed to "automatically fills, seals and places the card into the incubator/reader" and "monitors the growth of each well... At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result." The study confirms its performance against a reference method without human intervention in the interpretation process of the device results.

6. The type of ground truth used:

   • Expert Consensus/Pathology/Outcomes Data, etc.: The ground truth was established by the NCCLS reference broth microdilution method. This is a laboratory-based, standardized reference method for determining antimicrobial susceptibility.

7. The sample size for the training set:

   • Not applicable/Not mentioned. This device is described as an "essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) microdilution methodology." It is a hardware/chemistry-based system with an automated readout, not a machine learning or AI algorithm that requires a separate training set in the conventional sense. Its "training" or calibration would likely involve precise manufacturing and chemical formulation, not a data-driven training set.

8. How the ground truth for the training set was established:

   • Not applicable. As noted above, this device does not appear to rely on a data-driven training set with an established ground truth in the way AI algorithms do.

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