(315 days)
VITEK® 2 AST-Gram Positive Moxifloxacin 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 AST-Gram Positive Moxifloxacin is a quantitative test. Moxifloxacin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.
Active both in vitro and in clinical infections: Enterococcus faecalis Staphylococcus aureus
In vitro data are available, but their clinical significance is unknown: Staphylococcus epidermidis
The VITEK® 2 Gram-positive Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of Staphylococcus spp., Enterococcus spp., and S. agalactiae to antimicrobial agents when used as instructed.
The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh(1) and Gerlach(0). 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 only contains microbiological culture media is resident on all cards. The remaining wells contain premeasured portions of a specific antibiotic combined with culture media. The 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. 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 AST-Gram Positive Moxifloxacin, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implied by the "acceptable performance" statement and the presented data tables. The device's performance is compared against the CLSI (Clinical and Laboratory Standards Institute) agar dilution reference method.
| Metric (Agreement Type) | Acceptance Criteria (Implied) | Reported Device Performance | Microorganism | Notes |
|---|---|---|---|---|
| Essential Agreement (EA) | Not explicitly stated, but high EA is expected for "acceptable performance." | 98.7% | Enterococcus faecalis | Refers to agreement between the VITEK® 2 MIC value and the CLSI reference MIC. |
| Category Agreement (CA) | Not explicitly stated, but high CA is expected for "acceptable performance." | 99.4% | Enterococcus faecalis | Refers to agreement in interpretive categories (Susceptible, Intermediate, Resistant). |
| Very Major Errors (VME) | Low percentage desired. | 0.0% (0/43) | Enterococcus faecalis | Occurs when the VITEK® 2 calls an isolate susceptible but the reference method calls it resistant. |
| Major Errors (ME) | Low percentage desired. | 0.0% (0/110) | Enterococcus faecalis | Occurs when the VITEK® 2 calls an isolate resistant but the reference method calls it susceptible. |
| Minor Errors (mE) | Low percentage desired. | 0.6% (1/154) | Enterococcus faecalis | Occurs when the VITEK® 2 calls an isolate susceptible/resistant and the reference method calls it intermediate, or vice versa, or when both call it intermediate but with different MICs. |
| Essential Agreement (EA) | Not explicitly stated, but high EA is expected for "acceptable performance." | 94.9% | Staphylococcus spp. | Refers to agreement between the VITEK® 2 MIC value and the CLSI reference MIC. |
| Category Agreement (CA) | Not explicitly stated, but high CA is expected for "acceptable performance." | 99.4% | Staphylococcus spp. | Refers to agreement in interpretive categories (Susceptible, Intermediate, Resistant). |
| Very Major Errors (VME) | Low percentage desired. | 4.8% (16/331) | Staphylococcus spp. | Occurs when the VITEK® 2 calls an isolate susceptible but the reference method calls it resistant. |
| Major Errors (ME) | Low percentage desired. | 0.7% (1/152) | Staphylococcus spp. | Occurs when the VITEK® 2 calls an isolate resistant but the reference method calls it susceptible. |
| Minor Errors (mE) | Low percentage desired. | 0.0% (0/163) | Staphylococcus spp. | Occurs when the VITEK® 2 calls an isolate susceptible/resistant and the reference method calls it intermediate, or vice versa, or when both call it intermediate but with different MICs. |
| Reproducibility | Not explicitly stated, but 100% is shown for Quality Control. | 100.0% | Enterococcus faecalis Quality Control | Demonstrated acceptable results. |
| Reproducibility | Not explicitly stated, but 100% is shown for Quality Control. | N/A (Not specified for Staphylococcus spp. Quality Control) | Staphylococcus spp. Quality Control | Demonstrated acceptable results. |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size:
- Enterococcus faecalis: 154 isolates for overall agreement metrics. (Breakdown for VME/ME shows 43 for VME calculation, 110 for ME calculation, so the total number of isolates tested could be higher than 154 if not all isolates were discrepant in a way that led to VME or ME.)
- Staphylococcus spp.: 331 isolates for overall agreement metrics. (Breakdown for VME/ME shows 331 for VME calculation, 152 for ME calculation, 163 for mE calculation, similar note applies as above).
- Data Provenance: "External evaluation was conducted with fresh and stock clinical isolates, as well as a set of challenge strains." This indicates a mix of retrospective (stock/challenge strains) and prospective (fresh clinical isolates) data. The document does not specify the country of origin.
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. The ground truth is established by the CLSI agar dilution reference method, which is a standardized laboratory procedure, not typically by individual human experts evaluating images or making subjective interpretations.
4. Adjudication Method for the Test Set
This information is not applicable in the context of an antimicrobial susceptibility test where the ground truth is established by a reference laboratory method (CLSI agar dilution). There is no "adjudication" in the sense of multiple human readers resolving discrepancies.
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 information is not applicable as the device is an automated antimicrobial susceptibility system, not an AI-assisted diagnostic imaging tool for human readers. There is no human-in-the-loop component for interpretive decisions that would necessitate an MRMC study.
6. If a Standalone (i.e., Algorithm Only Without Human-in-the-Loop Performance) Was Done
Yes, this was a standalone performance evaluation. The VITEK® 2 system, which incorporates "Analysis Algorithms" (Discriminant Analysis), determines the MIC and interpretive category without human interpretive input. The study compared the device's automated results directly against the CLSI reference method.
7. The Type of Ground Truth Used
The ground truth used was the CLSI agar dilution reference method. This is a well-established, standardized laboratory method for determining the minimum inhibitory concentration (MIC) of an antimicrobial agent against a microorganism. It's a gold standard for antimicrobial susceptibility testing.
8. The Sample Size for the Training Set
This information is not provided in the document. The document describes the performance evaluation of the VITEK® 2 AST-GP Moxifloxacin system, which uses "Discriminant Analysis" algorithms. While algorithms often require training data, the specific training set size is not detailed in this 510(k) summary.
9. How the Ground Truth for the Training Set Was Established
This information is not provided in the document. Given that the device uses "Discriminant Analysis" and is based on microdilution techniques, it's highly likely that the training process involved internal laboratory data where a similar reference method (like CLSI agar dilution) was used to establish the ground truth for calibrating and optimizing the system's interpretive algorithms. However, the document does not specify this.
§ 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.”