(50 days)
VITEK® 2 Gram Negative Meropenem is designed for antimicrobial susceptibility testing of gramnegative 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 Negative Meropenem is a quantitative test. Meropenem has been shown to be active against most isolates of the following microorganisms listed below according to the FDA label for the antimicrobial.
Active in vitro and in clinical infections:
Escherichia coli Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Acinetobacter species Aeromonas hydrophila
Citrobacter diversus Citrobacter freundii Enterobacter cloacae Hafnia alvei Klebsiella oxytoca Morganella morganii
Pasteurella multocida Proteus vulgaris Salmonella species Serratia marcescens Shigella species
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 bacilli, Staphylococcus spp., Enterococcus spp., Streptococcus agalactiae, and S. pneumoniae.
The principle of the VITEK 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh " and Gerlach (2). The VITEK 2 AST card is essentially a miniaturized, abbreviated and automated version of the doubling dilution technique (3)
Each VITEK 2 AST card contains 64 wells. A control well which contains only microbiological culture media is resident on all cards. The remaining wells contain premeasured portions of a specific antibiotic combined with culture media. The bacterial isolate to be tested is diluted to a standardized concentration with 0.45 -0.5% 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, sealing and loading operation. The VITEK 2 Systems monitor 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 an analysis of the acceptance criteria and study details for the VITEK® 2 Gram Negative Meropenem device, based on the provided text:
Acceptance Criteria and Device Performance
1. Table of Acceptance Criteria and Reported Device Performance:
The document implicitly refers to performance requirements established by a Guidance Document, which the device is stated to meet. The specific quantitative acceptance criteria are not explicitly detailed in the provided text as ranges or thresholds, but rather the performance metrics achieved by the device are presented. The predicate device's performance is also included for comparative purposes, indicating what would be considered acceptable.
| Metric | Acceptance Criteria (Implicit from Guidance/Predicate) | Reported Device Performance (VITEK 2 GN Meropenem) | Predicate Device Performance (VITEK 2 GN Doripenem) |
|---|---|---|---|
| Essential Agreement (EA) | Expected to be high (e.g., in the range of the predicate) | 97.6% | 97.4% |
| Category Agreement (CA) | Expected to be high (e.g., in the range of the predicate) | 96.8% | 97.9% |
| Reproducibility (Best-case) | Expected to be high | 99.6% | 99.2% |
| Reproducibility (Worst-case) | Expected to be high | 99.6% | 90.6% |
| Quality Control | > 20 tests in range | > 20 tests in range | > 20 tests in range |
| Meets Guidance Document Performance Requirements | Yes | Yes | Yes |
2. Sample Size Used for the Test Set and Data Provenance:
The document states "Clinical studies were performed and demonstrate acceptable performance," but it does not provide the specific sample size for the test set used in the "Clinical & Challenge Performance Data."
The data provenance (e.g., country of origin of the data, retrospective or prospective) is not explicitly stated in the provided text. It can be inferred that these were controlled laboratory studies (clinical and challenge) rather than broad population studies.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:
The document does not provide information on the number of experts used or their qualifications to establish the ground truth for the test set.
4. Adjudication Method for the Test Set:
The document does not specify any adjudication method (e.g., 2+1, 3+1, none) used for the test set.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
A Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed as this device is an automated antimicrobial susceptibility test (AST) system. It determines in vitro susceptibility directly and does not involve human readers interpreting results for a "case" in the traditional sense. The "comparison" is against a standard reference method rather than human interpretation.
6. Standalone Performance (Algorithm Only Without Human-in-the-Loop Performance):
Yes, a standalone performance study was done. The VITEK® 2 system is an automated device designed to determine antimicrobial susceptibility directly from bacterial isolates. The reported performance metrics (EA, CA, Reproducibility) are for the device (algorithm) itself against a reference method, without human intervention as part of the primary diagnostic output. The VITEK 2 Compact has a manual filling, sealing, and loading operation, but the monitoring and result generation are automated.
7. Type of Ground Truth Used:
The ground truth for antimicrobial susceptibility testing is typically established using a standard reference method, such as broth microdilution or agar dilution as defined by CLSI (Clinical and Laboratory Standards Institute) guidelines. The document mentions that "The principle of the VITEK 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh ' and Gerlach (2)." It also refers to "Equivalent Standard Method Concentration." This strongly indicates that a standard microbiological reference method was used to establish the ground truth.
8. Sample Size for the Training Set:
The sample size for the training set is not explicitly stated in the provided text.
9. How the Ground Truth for the Training Set Was Established:
The document does not explicitly describe how the ground truth for the training set was established. However, given the nature of AST devices, it would invariably involve testing bacterial isolates against a standard reference method (as described in point 7) to generate the MIC values and interpretive categories, which would then be used to train and validate the device's algorithms.
§ 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.”