(84 days)
VITEK® 2 AST-Gram Negative Meropenem/Vaborbactam is designed for antimicrobial susceptibility testing of Gram Negative bacilli 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 AST-Gram Negative Meropenem/Vaborbactam is a quantitative test. Meropenem/Vaborbactam 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:
Enterobacter cloacae complex
Escherichia coli
Klebsiella pneumoniae
In vitro data available but clinical significance unknown:
Citrobacter freundii
Citrobacter koseri
Klebsiella (Enterobacter) aerogenes
Klebsiella oxytoca
Morganella morganii
Proteus mirabilis
Providencia spp.
Serratia marcescens
The VITEK® 2 Gram-negative Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinically significant aerobic Gram-negative bacilli to antimicrobial agents when used as instructed.
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.
Here's an analysis of the acceptance criteria and study data provided for the VITEK® 2 AST-GN Meropenem/Vaborbactam device:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Guidance Document) | Reported Device Performance |
|---|---|---|
| Essential Agreement (EA) | (Implicitly understood to be high, generally >90% for AST systems) | 98.2% overall |
| Category Agreement (CA) | (Implicitly understood to be high, generally >90% for AST systems) | 98.7% overall |
| Reproducibility | Acceptable results (specific threshold not provided, but implying meeting standards) | Demonstrated acceptable results |
| Quality Control | Acceptable results (specific threshold not provided, but implying meeting standards) | Demonstrated acceptable results |
Note: The document references the "FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (Issued August 28, 2009)" for defining comparable performance. While specific numeric acceptance criteria for EA and CA aren't explicitly stated within this document, regulatory expectations for AST systems generally require high agreement percentages (often >90%) for both metrics. The reported performance clearly exceeds these implicit expectations.
2. Sample Size Used for the Test Set and Data Provenance
- 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." This suggests a diverse test set, but the total count of isolates is not provided.
- Data Provenance: The document does not specify the country of origin. The data is described as from "clinical isolates" (which implies prospective, real-world samples) and "stock clinical isolates" (which could be retrospective or stored prospective samples) and "challenge strains" (which are typically lab-generated or curated for specific resistance patterns).
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 document. For antimicrobial susceptibility testing, the "ground truth" is typically established by a reference method (broth microdilution in this case), not via human experts in the traditional sense of image interpretation or clinical diagnosis.
4. Adjudication Method for the Test Set
- This information is not applicable in the context of AST system validation as described. Ground truth is established by a reference laboratory method (CLSI broth microdilution), not through expert adjudication.
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
- No, an MRMC comparative effectiveness study was not done. This device is a fully automated antimicrobial susceptibility testing system, an "algorithm only" device. There is no human "reader" in the loop for interpreting the results, as the system provides an MIC value and interpretive category.
6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done
- Yes, a standalone performance study was done. The VITEK® 2 AST-GN Meropenem/Vaborbactam is described as a "fully automated short-term incubation cycle antimicrobial susceptibility system." Its performance was compared against the CLSI broth microdilution reference method, indicating an evaluation of the device's inherent capability to determine susceptibility.
7. The Type of Ground Truth Used
- The ground truth used was the CLSI broth microdilution reference method, incubated at 16-20 hours, as defined in the FDA Class II Special Controls Guidance Document for AST Systems. This is considered the gold standard for determining MIC values.
8. The Sample Size for the Training Set
- Not provided. The document details an "external evaluation" which serves as the validation or test set. Information regarding a separate training set (if applicable to the development of the VITEK 2 system's algorithms for this specific AST card) is not included in this 510(k) summary.
9. How the Ground Truth for the Training Set was Established
- Not provided, as the details of a training set are not present in this document. If a training set was used (e.g., for initial algorithm development), it would presumably also rely on a reference method like broth microdilution for ground truth, similar to the test set.
§ 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.”