(47 days)
The VITEK® 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK 2 System 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. VITEK 2 Gram Positive Daptomycin is designed for antimicrobial susceptibility testing of Enterococcus faecalis, Staphylococcus aureus, Streptococcus agalactiae, Enterococcus faecium, Staphylococcus epidermidis and Staphylococcus haemolyticus. VITEK 2 Gram Positive Daptomycin is a quantitative test. It is intended for use with the VITEK 2 System as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents.
The VITEK 2 AST Cards are essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) microdilution methodology. The bacterial isolate to be tested is diluted to a standardized concentration in 0.45% 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 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 antibiotic contained on the card.
Here's a breakdown of the acceptance criteria and study details based on the provided text for the VITEK® 2 Gram Positive Daptomycin device:
Acceptance Criteria and Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Overall Essential Agreement (EA) | 98.2% |
| Overall Category Agreement (CA) | 100% |
Note: The specific numerical acceptance thresholds are not explicitly stated in the provided text, but the reported performance values are presented as demonstrating "acceptable performance" and "substantially equivalent performance" when compared to the reference method, as defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA, Issued Feb. 5, 2003.
Study Details:
-
Sample size used for the test set and the data provenance:
- Test Set Sample Size: Not explicitly stated as a numerical value. The study mentions "fresh and stock clinical isolates and stock challenge strains."
- Data Provenance: Not explicitly stated (e.g., country of origin). The nature ("fresh and stock clinical isolates") suggests real-world patient samples, but the geographic origin is not specified. It was a prospective evaluation in the sense that the VITEK 2 was compared against a reference method in a controlled study design.
-
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- Not applicable/Not mentioned. The ground truth was established by a recognized reference method, not by expert consensus.
-
Adjudication method for the test set:
- Not applicable/Not mentioned. Adjudication by experts is not relevant when comparing a device to a defined reference standard method.
-
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 device is an automated antimicrobial susceptibility testing system, not an AI-assisted diagnostic intended for human reader interpretation improvement. The comparison is between the automated system and a laboratory reference method.
-
If a standalone (i.e. algorithm only, without human-in-the-loop performance) was done:
- Yes, this was a standalone performance study. The VITEK® 2 system is an automated device designed to "automatically fills, seals and places the card into the incubator/reader" and "monitors the growth of each well... At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result." The study confirms its performance against a reference method without human intervention in the interpretation process of the device results.
-
The type of ground truth used:
- Expert Consensus/Pathology/Outcomes Data, etc.: The ground truth was established by the NCCLS reference broth microdilution method. This is a laboratory-based, standardized reference method for determining antimicrobial susceptibility.
-
The sample size for the training set:
- Not applicable/Not mentioned. This device is described as an "essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) microdilution methodology." It is a hardware/chemistry-based system with an automated readout, not a machine learning or AI algorithm that requires a separate training set in the conventional sense. Its "training" or calibration would likely involve precise manufacturing and chemical formulation, not a data-driven training set.
-
How the ground truth for the training set was established:
- Not applicable. As noted above, this device does not appear to rely on a data-driven training set with an established ground truth in the way AI algorithms do.
§ 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.”