(84 days)
VITEK® 2 Gram Negative Gentamicin is designed for antimicrobial susceptibility testing of Gram negative bacilli and is intended for use with the VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK® 2 Gram Negative Gentamicin is a quantitative test. Gentamicin 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 Citrobacter species Enterobacter species Escherichia coli Klebsiella species Proteus species Serratia species Pseudomonas aeruginosa
The VITEK® 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, Staphylococus 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 provided text describes the performance of the VITEK® 2 AST-GN Gentamicin device for antimicrobial susceptibility testing. Here's a breakdown of the acceptance criteria and the study that proves the device meets them:
Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Metric) | Reported Device Performance (%) |
|---|---|
| Overall Essential Agreement (EA) | 99.4% |
| Overall Category Agreement (CA) | 98.6% |
Study Details
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Sample Size Used for the Test Set and Data Provenance:
- The document states that an "external evaluation was conducted with fresh and stock clinical isolates, as well as a set of challenge strains." However, specific sample sizes for these test sets are not provided in the document.
- The data provenance regarding the country of origin or whether it was retrospective or prospective is not explicitly stated. It can be inferred that it involved clinical isolates, suggesting real-world samples, but the collection method (retrospective/prospective) is not detailed.
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Number of Experts Used to Establish Ground Truth and Qualifications:
- This information is not provided in the document, as the ground truth was established by a reference method rather than human experts interpreting results.
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Adjudication Method for the Test Set:
- Adjudication methods (e.g., 2+1, 3+1) are not applicable here because the ground truth was established by a quantitative reference method (CLSI broth microdilution) rather than expert consensus requiring reconciliation.
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Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- No, an MRMC study was not done. This type of study is typically performed for imaging devices where human readers interpret medical images. The VITEK® 2 is an automated antimicrobial susceptibility testing system, so its performance is compared directly to a reference laboratory method, not to human interpretation of images. Therefore, improvement of human readers with AI assistance is not applicable.
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Standalone Performance:
- Yes, a standalone performance evaluation was done. The described study focuses on the device's performance (VITEK® 2 AST-GN Gentamicin) compared to the CLSI broth microdilution reference method, which represents the algorithm's performance without specific human-in-the-loop assistance in the interpretation of the susceptibility results, beyond standard laboratory handling. The VITEK® 2 is an automated system that generates a report with MIC values and interpretive categories.
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Type of Ground Truth Used:
- The ground truth used was the CLSI broth microdilution reference method, specifically incubated at 16-20 hours. This is a laboratory standard for determining minimum inhibitory concentrations (MICs) of antimicrobials.
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Sample Size for the Training Set:
- The document does not provide the sample size for any training set. This is because the VITEK® 2 system, as described, is likely based on established microbiological principles and a defined algorithm for growth detection and MIC calculation, rather than a machine learning model that requires explicit training data in the context of typical AI/ML studies. The evaluation described is for validation of the device's performance against a reference method.
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How the Ground Truth for the Training Set Was Established:
- As there's no mention of a traditional "training set" in the context of a machine learning model, this question is not fully applicable. The core methodology of the VITEK® 2 system (miniaturized versions of the doubling dilution technique) is based on the established science of antimicrobial susceptibility testing, with the CLSI broth microdilution method serving as the gold standard for validating its output.
§ 866.1645 Fully automated short-term incubation cycle antimicrobial susceptibility system.
(a)
Identification. A fully automated short-term incubation cycle antimicrobial susceptibility system is a device that incorporates concentrations of antimicrobial agents into a system for the purpose of determining in vitro susceptibility of bacterial pathogens isolated from clinical specimens. Test results obtained from short-term (less than 16 hours) incubation are used to determine the antimicrobial agent of choice to treat bacterial diseases.(b)
Classification. Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA.”