(83 days)
VITEK® 2 AST-Gram Negative Delafloxacin is designed for antimicrobial susceptibility testing of Gram Negative bacilli 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 Negative Delafloxacin is a quantitative test. Delafloxacin 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: Enterobacter cloacae Escherichia coli Klebsiella pneumoniae Pseudomonas aeruginosa
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, Staphylococcus spp., Enterococcus spp., Streptococcus 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.
This document describes the validation of the VITEK® 2 AST-GN Delafloxacin system for antimicrobial susceptibility testing.
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Acceptance Criteria and Device Performance
| Metric | Acceptance Criteria (from FDA Class II Special Controls Guidance Document) | Reported Device Performance |
|---|---|---|
| Overall Essential Agreement | Not explicitly stated as a percentage, but implied acceptable. | 98.0% |
| Overall Category Agreement | Not explicitly stated as a percentage, but implied acceptable. | 95.9% |
| Reproducibility | Acceptable | Demonstrated Acceptable |
| Quality Control | Acceptable | Demonstrated Acceptable |
Note: The document refers to the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems (Issued August 28, 2009) as defining the essential and category agreement requirements, but the specific percentage thresholds are not included in this extract. The reported performance is stated as "demonstrated acceptable performance" against this guidance.
Study Design and Data Details
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Sample Size used for the Test Set and the Data Provenance:
- Test Set Sample Size: Not explicitly stated as a numerical value, but the evaluation included "fresh and stock clinical isolates, as well as a set of challenge strains."
- Data Provenance: Not specified regarding country of origin. The study was an "external evaluation," and it included "fresh and stock clinical isolates." This suggests the data is likely retrospective (stock clinical isolates) and potentially prospective (fresh clinical isolates) if collected specifically for this study. The document does not specify if the data was from a single geographical region or multiple.
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Number of Experts used to establish the Ground Truth for the Test Set and the Qualifications of those Experts:
- This information is not provided in the document. The ground truth was established by comparison to a reference method, not by expert consensus on individual cases.
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Adjudication Method for the Test Set:
- None in the context of human expert adjudication. The "adjudication" was inherently built into the comparison with the CLSI broth microdilution reference method. Discrepancies would be analyzed against this gold standard.
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If a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was done:
- No, this was not an MRMC study. This device is an automated antimicrobial susceptibility testing system, not an AI-assisted diagnostic tool for human readers. Therefore, the concept of human readers improving with AI assistance does not apply.
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If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, in essence. The study evaluated the VITEK® 2 AST-GN Delafloxacin system's performance (which is an automated system/algorithm) against a reference laboratory method (CLSI broth microdilution). The performance metrics (Essential Agreement, Category Agreement) directly reflect the device's accuracy in determining MIC values and interpretive categories. Human intervention is limited to sample preparation and loading, not interpretation of raw data for diagnosis.
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The Type of Ground Truth Used:
- The ground truth was established using the CLSI broth microdilution reference method, incubated at 16-20 hours. This is a well-established and accepted reference standard in microbiology for determining minimum inhibitory concentrations (MICs) of antimicrobials.
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The Sample Size for the Training Set:
- This information is not provided in the document. The VITEK® 2 system is a mature technology, and its underlying AST methodology likely has a long history of development and "training" on vast amounts of microbial data to establish its algorithms for growth detection and MIC determination. This specific submission focuses on the validation of Delafloxacin on this existing platform, implying the core AST algorithm was already established.
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How the Ground Truth for the Training Set was established:
- This information is not provided in the document. Similar to point 7, the "training" of the VITEK® 2 system's core AST methodology would have involved extensive historical data and comparisons to reference methods like CLSI broth microdilution to develop its algorithms.
§ 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.”