(53 days)
VITEK® 2 AST-Gram Positive Delafloxacin 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 AST-Gram Positive 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: Acute Bacterial Skin and Skin Structure Infections (ABSSSI):
Staphylococcus aureus (including methicillin-resistant and methicillin-susceptible isolates) Streptococcus agalactiae Enterococcus faecalis
Community-Acquired Bacterial Pneumonia (CABP):
Staphylococcus aureus (methicillin-susceptible isolates only)
The VITEK® 2 Gram-positive Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of Staphylococcus spp., Enterococcus spp., and S. agalactiae to antimicrobial agents when used as instructed.
The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh() and Gerlach(0). The VITEK @ 2 AST card is essentially a miniaturized, abbreviated and automated version of the doubling dilution technique(3).
Each VITEK® 2 AST card contains 64 wells. A control well which only contains microbiological culture media is resident on all cards. The remaining wells contain premeasured portions of a specific antibiotic combined with culture media. The isolate to be tested is diluted to a standardized concentration with 0.45 – 0.5% 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, sealing and loading operation. The VITEK® 2 Systems monitor the growth of each well in the card over a defined period of time. 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 an analysis of the acceptance criteria and study details based on the provided document:
Acceptance Criteria and Device Performance for VITEK® 2 AST-Gram Positive Delafloxacin
The device, VITEK® 2 AST-Gram Positive Delafloxacin, is an antimicrobial susceptibility testing system. Its performance was compared against the CLSI broth microdilution reference method.
1. Table of Acceptance Criteria and Reported Device Performance
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) as the definition for acceptable performance. While the specific numerical acceptance criteria from this guidance are not explicitly stated in the provided text, the table below presents the reported device performance, which the document states "demonstrated acceptable performance."
| Performance Metric | Target/Acceptance Criteria (Implicitly met based on "acceptable performance") | Reported Device Performance (Delafloxacin) |
|---|---|---|
| Percentage Essential Agreement (%EA) | ||
| ABSSSI (Overall) | N/A (implicitly >X%) | 96.6% (737/763) |
| ABSSSI (E. faecalis) | N/A (implicitly >X%) | 95.0% (342/360) |
| ABSSSI (MSSA+MRSA) | N/A (implicitly >X%) | 98.2% (320/326) |
| ABSSSI (S. agalactiae) | N/A (implicitly >X%) | 97.4% (75/77) |
| CABP (MSSA) | N/A (implicitly >X%) | 99.4% (169/170) |
| Percentage Category Agreement (%CA) | ||
| ABSSSI (Overall) | N/A (implicitly >X%) | 94.0% (717/763) |
| ABSSSI (E. faecalis) | N/A (implicitly >X%) | 94.4% (340/360) |
| ABSSSI (MSSA+MRSA) | N/A (implicitly >X%) | 92.0% (300/326) |
| ABSSSI (S. agalactiae) | N/A (implicitly >X%) | 100.0% (77/77) |
| CABP (MSSA) | N/A (implicitly >X%) | 97.1% (165/170) |
| Very Major Errors (VME) | N/A (implicitly X%) | 100.0% (for Delafloxacin - unspecified organism type) |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Organisms: The document states that "An external evaluation was conducted with contemporary and stock clinical isolates, as well as a set of challenge strains." Specific numbers for each organism type tested within the overall categories are provided in the performance table (e.g., 763 isolates for ABSSSI Overall, 360 for E. faecalis, 326 for MSSA+MRSA, 77 for S. agalactiae, 170 for CABP MSSA).
- Data Provenance: The document explicitly mentions "contemporary and stock clinical isolates." This suggests a mix of retrospective (stock isolates) and potentially prospective (contemporary clinical isolates) data. The country of origin is not specified.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
This information is not provided in the document. The ground truth was established by the CLSI broth microdilution reference method, which is a standardized laboratory procedure, not typically an expert consensus based on individual interpretation.
4. Adjudication Method for the Test Set
This information is not applicable for this type of test (Antimicrobial Susceptibility Testing). Adjudication methods like 2+1 or 3+1 are typically used in image-based diagnostic studies where multiple human readers are involved and their interpretations need to be reconciled. In AST, the reference method provides a direct, quantitative result.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
A MRMC comparative effectiveness study was not done. This type of study assesses the performance of human readers, sometimes with and without AI assistance. This document describes the performance of an automated AST device against a reference method, not human interpretation.
6. Standalone (Algorithm Only) Performance
Yes, a standalone performance study was done. The entire evaluation described in the "Performance Overview and Conclusion" section focuses on the performance of the VITEK® 2 AST-Gram Positive Delafloxacin system (algorithm only) against the CLSI broth microdilution reference method, without human intervention in the result determination by the VITEK system.
7. Type of Ground Truth Used
The ground truth used was the CLSI broth microdilution reference method. This is a laboratory-based, standardized, quantitative method for determining minimum inhibitory concentrations (MICs) of antimicrobial agents.
8. Sample Size for the Training Set
The document does not specify the sample size used for the training set. It only describes the "external evaluation" which appears to be the test set.
9. How the Ground Truth for the Training Set Was Established
The document does not specify how the ground truth for any potential training set was established. However, given that the external evaluation used the CLSI broth microdilution reference method, it is highly probable that any training data would have also been benchmarked against a similar gold standard 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.”