(79 days)
VITEK® 2 AST-Gram Negative Cefepime 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 AST-Gram Negative Cefepime is a quantitative test. Cefepime 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 spp. Escherichia coli Klebsiella pneumoniae Proteus mirabilis Pseudomonas aeruginosa
In vitro data available but clinical significance is unknown: Citrobacter koseri (formerly Citrobacter diversus) Citrobacter freundii Pantoea agglomerans (formerly Enterobacter agglomerans) Klebsiella oxytoca Proteus vulgaris Providencia rettgeri Providencia stuartii Serratia marcescens
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 antimicrobial presented in VITEK® 2 AST-GN Cards is in concentrations equivalent by efficacy to standard method concentrations in mcg/ml. 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 a breakdown of the acceptance criteria and study details for the VITEK® 2 AST-GN Cefepime device, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Metric | Acceptance Criteria (Not Explicitly Stated, but Implied by "Acceptable Performance") | Reported Device Performance |
|---|---|---|
| Overall Essential Agreement (EA) | Not explicitly stated (implied to be high) | 93.8% |
| Overall Category Agreement (CA) | Not explicitly stated (implied to be high) | 96.1% |
| Reproducibility | Acceptable results | Acceptable results |
| Quality Control | Acceptable results | Acceptable results |
Note: The document states that the device "demonstrated substantially equivalent performance when compared with 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 August 28, 2009)." While specific numerical acceptance criteria are not provided in the snippet, the reported percentages (93.8% EA and 96.1% CA) are considered acceptable by the FDA based on the comparison to the CLSI reference method.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set: Not explicitly stated as a numerical value. However, the study involved "fresh and stock clinical isolates, as well as a set of challenge strains." This suggests a diverse collection of bacterial samples.
- Data Provenance: The document does not specify the country of origin. It indicates the use of "fresh and stock clinical isolates" which implies retrospective data collection from a clinical setting, complemented by "challenge strains," which are likely laboratory-derived. It's a combination of clinical (retrospective) and contrived (challenge strains) data.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number of experts or their qualifications for establishing the ground truth.
4. Adjudication Method for the Test Set
The document does not explicitly state an adjudication method. The comparison relies on the "CLSI broth microdilution reference method," which is a standardized laboratory procedure, not typically subject to expert adjudication in the same way an imaging study would be.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study was not done. This type of study is relevant for devices that assist human readers in interpretation (e.g., AI for radiology). The VITEK® 2 AST-GN Cefepime is an automated system for determining antimicrobial susceptibility, comparing its results to a standardized reference method, not to human readers.
6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done
Yes, a standalone study was done. The entire study described is a standalone performance evaluation of the VITEK® 2 AST-GN Cefepime system (algorithm only) against the CLSI broth microdilution reference method. There is no mention of a human-in-the-loop component.
7. The Type of Ground Truth Used
The ground truth used was the CLSI broth microdilution reference method incubated at 16-20 hours. This is a highly standardized and accepted laboratory method for determining minimum inhibitory concentrations (MICs) of antimicrobial agents, serving as the gold standard for AST.
8. The Sample Size for the Training Set
The document does not provide information regarding a separate training set size. The study described focuses on the performance evaluation of the device. Given the nature of a laboratory testing system, it's possible the "training" (development and calibration) was an internal process, distinct from the external validation study reported.
9. How the Ground Truth for the Training Set Was Established
As no specific training set is detailed, the method for establishing its ground truth is also not described. It is implicitly understood that the principles of antimicrobial susceptibility testing, particularly methods like broth microdilution, would have been used during the device's internal development and calibration.
§ 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.”