(179 days)
VITEK® 2 Gram Negative Doxycycline is designed for antimicrobial susceptibility testing of Gramnegative bacilli. VITEK 2 Gram Negative Doxycycline is a quantitative test 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. Doxycycline has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.
Active in vitro and in clinical infections
Acinetobacter species
Enterobacter aerogenes
Escherichia coli
Klebsiella species
Shigella species
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 spp., S. pneumoniae, 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.
Here's an analysis of the acceptance criteria and study detailed in the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Overall Essential Agreement (EA) | Not explicitly stated, but generally >90% for AST systems | 97.6% |
| Overall Category Agreement (CA) | Not explicitly stated, but generally >90% for AST systems | 95.1% |
Note: The document states "VITEK® 2 GN Doxycycline demonstrated substantially equivalent performance when compared with the CLSI broth microdilution reference method, as defined in 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 acceptance criteria for EA and CA, which are generally high for such devices (e.g., >90% or >95%). Since the device met the criteria, we can infer that the reported values satisfy regulatory thresholds.
2. Sample Size Used for the Test Set and Data Provenance
- 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 external evaluation is not provided.
- Data Provenance: The document mentions "An 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 clinical isolates) and potentially prospective (fresh clinical isolates) data. The country of origin is not specified, but bioMérieux, Inc. is located in Hazelwood, MO, USA, and the submission is to the FDA, suggesting the data is likely from the US or a region adhering to similar clinical standards.
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 (reference method) used was the CLSI broth microdilution reference method. While this method involves expert execution and interpretation, the document does not detail the number or qualifications of individuals performing or verifying the reference method results.
4. Adjudication Method for the Test Set
- This information is not provided in the document. For antimicrobial susceptibility testing, discrepancies would typically be resolved by repeat testing or referral to a third, expert laboratory, but the specific adjudication method is not mentioned.
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, an MRMC comparative effectiveness study was not done. This device is an automated antimicrobial susceptibility testing (AST) system. It directly produces interpretive results (susceptible, intermediate, resistant) based on Minimum Inhibitory Concentration (MIC) values. It is not designed to assist human readers in interpreting images or clinical cases, but rather to automate a laboratory test. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply here.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
- Yes, a standalone performance evaluation was conducted. The VITEK® 2 system is a fully automated system. The evaluation compared the device's automated results (MIC values and interpretive categories) directly against the CLSI broth microdilution reference method, which is the gold standard for AST. This is a standalone assessment of the device's performance.
7. The Type of Ground Truth Used
- Expert Consensus / Reference Method: The ground truth was established using the CLSI (Clinical and Laboratory Standards Institute) broth microdilution reference method, which is the gold standard for determining antimicrobial susceptibility. This method is internationally recognized and relies on standardized protocols and expert interpretation.
8. The Sample Size for the Training Set
- This information is not provided in the document. The document focuses on the external evaluation (test set) for validation. VITEK® 2 systems are pre-calibrated and validated; specific "training sets" in the machine learning sense are not typically reported in 510(k) summaries for these types of devices, as they often rely on established biochemical and growth kinetics algorithms rather than deep learning models requiring explicit training data.
9. How the Ground Truth for the Training Set was Established
- This information is not provided in the document, as no specific "training set" in the context of a machine learning model is described for this device. The underlying algorithms and interpretations for VITEK® 2 systems are developed based on extensive microbiology principles and correlation with reference methods over many years of research and development. The ground truth for the development and internal validation of such systems would also involve the CLSI broth microdilution reference method.
§ 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.”