(57 days)
VITEK® 2 Gram Positive Moxifloxacin for Streptococcus pneumoniae is designed for antimicrobial susceptibility testing of Streptococcus pneumoniae. 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) my 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 an analysis of the provided text regarding the VITEK® 2 Gram Positive Moxifloxacin for Streptococcus pneumoniae device, focusing on acceptance criteria and supporting study details:
1. Table of Acceptance Criteria and Reported Device Performance:
The document refers to "acceptable performance" as defined in the Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; guidance for Industry and FDA. Issued February 5, 2003. While the specific numerical acceptance criteria from this guidance document are not explicitly detailed in the provided text, the device's performance against these unstated criteria is reported.
| Acceptance Criterion (from referenced guidance) | Reported Device Performance |
|---|---|
| Overall Essential Agreement (EA) | 99.6% |
| Reproducibility | Acceptable |
| Quality Control | Acceptable |
Note: The exact numerical thresholds for "Acceptable" for Reproducibility and Quality Control are not specified in the provided text but would be defined in the referenced FDA guidance document.
2. Sample Size Used for the Test Set and Data Provenance:
- Sample Size for Test Set: Not explicitly stated in terms of a specific number of isolates. The document mentions "fresh and stock clinical isolates and stock challenge strains" were used in the external evaluation.
- Data Provenance: Not explicitly stated (e.g., country of origin). The study involved "external evaluations," implying multiple locations, but specific geographic details are absent. The isolates were a mix of "fresh and stock clinical isolates" (implying retrospective and potentially prospective clinical samples) and "stock challenge strains."
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications:
- Number of Experts: Not specified.
- Qualifications of Experts: Not specified. The ground truth was established by the NCCLS reference microbroth dilution method. While this method is performed by laboratory personnel, the document does not specify if "experts" (e.g., microbiologists with specific experience) formally established or adjudicated the ground truth results, beyond adhering to the standard method.
4. Adjudication Method for the Test Set:
- Adjudication Method: Not explicitly described. The primary method for establishing ground truth was the NCCLS reference microbroth dilution method. This method inherently provides a reference result, and the document does not mention a separate adjudication process for reconciling differing interpretations between multiple readers or methods.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done:
- No, an MRMC comparative effectiveness study was not explicitly described. The study focused on comparing the VITEK® 2 system's performance against a reference method (NCCLS microbroth dilution), not on the improvement of human readers with AI assistance.
6. If a Standalone (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 ("algorithm only" in the sense that it automatically processes and interprets results without direct human intervention in the interpretation of that specific test). Its performance was compared directly to the NCCLS reference method. The "report is generated that contains the MIC value along with the interpretive category result for each antibiotic contained on the card," indicating an automated output.
7. The Type of Ground Truth Used:
- Type of Ground Truth: The ground truth was established using the NCCLS reference microbroth dilution method. This is considered a gold standard in vitro laboratory method for antimicrobial susceptibility testing.
8. The Sample Size for the Training Set:
- Sample Size for Training Set: Not explicitly stated. The document describes an "external evaluation" for confirming acceptability, but it does not detail a separate training phase or the size of a training dataset. Given this is a 510(k) for an AST device, the "training" (development and refinement) of the AST algorithm would likely have involved extensive historical data and might not be documented as a distinct "training set" in the same way an AI/ML model for image interpretation would be.
9. How the Ground Truth for the Training Set Was Established:
- How Ground Truth for Training Set Was Established: Not explicitly stated. If there was an internal training or development phase, it's highly probable that the ground truth for that phase would also have been established using the NCCLS reference microbroth dilution method, as it is the accepted standard. However, the document does not provide details on this.
§ 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.”