(239 days)
VITEK® 2 Yeast Flucytosine is designed for antimicrobial susceptibility testing of clinically significant yeast species 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 Yeast Flucytosine is a quantitative test. Flucytosine has been shown to be active against most isolates of the microorganisms listed below, according to the FDA label for this antifungal.
Active in vitro and in clinical infections Candida albicans
The following in vitro data are available, but their clinical significance is unknown. Candida dubliniensis Candida glabrata Candida guilliermondii Candida lusitaniae Candida parapsilosis Candida tropicalis
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. 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 VITEK® 2 AST-YS Flucytosine device is designed for antimicrobial susceptibility testing of clinically significant yeast species (Candida species) and is intended for use with the VITEK® 2 and VITEK® 2 Compact Systems. It provides a quantitative test to determine in vitro susceptibility to antimicrobial agents.
1. A table of acceptance criteria and the reported device performance
| Performance Metric | Acceptance Criteria (Implicit from Guidance) | Reported Device Performance |
|---|---|---|
| Essential Agreement (EA) | Not explicitly stated, but typically ≥ 90% | 98.8% Overall |
| Category Agreement (CA) | Not explicitly stated, but typically ≥ 90% | 98.5% Overall |
| Reproducibility | "acceptable results" | "acceptable results" |
| Quality Control | "acceptable results" | "acceptable results" |
Note on Acceptance Criteria: The document refers to the "FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA. Issued August 28, 2009." This guidance document would contain the specific performance acceptance criteria for Essential Agreement and Category Agreement. Without direct access to this document, the reported performance metrics (98.8% EA and 98.5% CA) are generally considered excellent and likely meet or exceed standard acceptance thresholds for AST devices.
2. Sample sized used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)
- 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." The exact number of isolates for the test set is not provided in this summary.
- Data Provenance: Not specified regarding country of origin. The data includes "clinical isolates," implying real-world samples, and "challenge strains," which are likely laboratory-controlled strains used to test performance across the range of expected behaviors. The evaluation was an "external evaluation," suggesting independent testing beyond the manufacturer's internal labs. The study refers to "fresh and stock clinical isolates," which implies a prospective (fresh isolates) and retrospective (stock isolates) component.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)
Not applicable. The ground truth for this device is established by a reference laboratory method, not expert human interpretation.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set
Not applicable. Ground truth is established by a reference method, not a panel of human adjudicators.
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
Not applicable. This is an automated antimicrobial susceptibility test system, not an AI-assisted diagnostic device requiring human reader improvement studies.
6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done
Yes, a standalone study was conducted. The VITEK® 2 AST-YS Flucytosine device's performance was compared directly against the CLSI broth microdilution reference method (the gold standard). The reported Essential Agreement and Category Agreement percentages directly reflect the device's standalone performance.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)
The ground truth was established by the CLSI broth microdilution reference method. This is a widely accepted, standardized laboratory procedure for determining the minimum inhibitory concentration (MIC) of an antimicrobial agent against a microorganism. The incubation period for this reference method was 48 hours.
8. The sample size for the training set
The document does not explicitly mention a "training set" or its size in the context of device development. Given that this is an AST system, the device's "training" would primarily involve the development and calibration of the photometric algorithms that detect growth and determine MIC values based on known responses of various microorganisms to different antimicrobial concentrations. This development process isn't typically referred to as a "training set" in the same way an AI model is trained.
9. How the ground truth for the training set was established
Not explicitly detailed for a "training set" as described above. The general principle would involve establishing ground truth via the CLSI broth microdilution reference method for a diverse set of isolates to calibrate the VITEK® 2 system's algorithms for accurate MIC determination.
§ 866.1640 Antimicrobial susceptibility test powder.
(a)
Identification. An antimicrobial susceptibility test powder is a device that consists of an antimicrobial drug powder packaged in vials in specified amounts and intended for use in clinical laboratories for determining in vitro susceptibility of bacterial pathogens to these therapeutic agents. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.(b)
Classification. Class II (performance standards).