(53 days)
VITEK® 2 Gram Positive Tigecycline 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 Gram Positive Tigecycline is a qualitative test. Tigecycline has been shown to be active against the organisms listed below according to the FDA label for the antimicrobial.
Active in vitro and in clinical infections:
Enterococcus faecalis (Vancomycin-susceptible isolates only) Staphylococcus aureus (methicillin-susceptible and -resistant isolates) Streptococcus agalactiae
Active in vitro but their clinical significance is unknown: Enterococcus faecium (Vancomycin susceptible and resistant isolates) Staphylococcus epidermidis Staphylococcus haemolyticus Enterococcus casseliflavus.
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 gramnegative bacilli, Staphylococcus spp., Enterococcus spp., Streptococcus agalactiae, and S. pneumoniae.
The antimicrobial presented in VITEK 2 AST 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 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 System 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 MC value along with the interpretive category result for each antibiotic contained on the card.
This document describes the VITEK® 2 Gram Positive Tigecycline device, which is an automated system for antimicrobial susceptibility testing of Gram-positive microorganisms.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Defined by FDA Class II Special Controls Guidance Document) | Reported Device Performance (VITEK® 2 Gram Positive Tigecycline) |
|---|---|
| Substantial equivalence to CLSI broth microdilution reference method | 99.4% overall Category Agreement with CLSI broth microdilution reference method |
| Acceptable Reproducibility | Demonstrated acceptable results |
| Acceptable Quality Control | Demonstrated acceptable results |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: Not explicitly stated as a numerical value for the test set but implies a collection of isolates. The document refers to "fresh and stock clinical isolates and stock challenge strains."
- Data Provenance: The study involved an "external evaluation" using "fresh and stock clinical isolates and stock challenge strains." This suggests a combination of retrospective (stock isolates/strains) and potentially prospective (fresh clinical isolates) data. The country of origin is not specified, but the submission is to the US FDA, implying relevance to a US context or similar regulatory standards.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
- The document does not mention the number of experts or their qualifications for establishing the ground truth.
- The ground truth was established by the CLSI broth microdilution reference method, which is a standardized laboratory procedure, not typically an expert consensus per se.
4. Adjudication Method for the Test Set
- There is no mention of an adjudication method (such as 2+1 or 3+1) for the test set. The comparison was directly against the CLSI broth microdilution reference method.
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?
- No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted.
- This device is an automated system for antimicrobial susceptibility testing which determines MIC values and interpretive categories. It does not involve human readers interpreting images or data where AI assistance would directly improve human performance in the same way as, for example, diagnostic imaging. The "AI" here is the automated system itself.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
- Yes, a standalone performance evaluation was done. The VITEK® 2 system is an automated device designed to perform antimicrobial susceptibility testing "without human-in-the-loop performance" during the measurement and interpretation stages of the test itself. The evaluation compared the device's results directly to the CLSI reference method.
7. The Type of Ground Truth Used
- The ground truth used was the CLSI broth microdilution reference method. This is a well-established, standardized laboratory method for determining minimum inhibitory concentrations (MICs) of antimicrobials.
8. The Sample Size for the Training Set
- The document does not specify a separate "training set" or its sample size. This type of device, an automated AST system, is typically developed and validated against a large number of known isolates and reference methods rather than trained anew on a specific dataset in the way a machine learning algorithm might be. The reported performance refers to the external evaluation data, which serves as a validation set.
9. How the Ground Truth for the Training Set Was Established
- Since a distinct "training set" is not mentioned, the method for establishing its ground truth is not provided. For the validation/external evaluation set, the ground truth was established by the CLSI broth microdilution reference method. This method involves preparing serial dilutions of the antimicrobial agent and inoculating them with a standardized bacterial suspension to determine the lowest concentration that inhibits visible bacterial growth (MIC).
§ 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.”