(84 days)
The BD Phoenix™ Automated Microbiology System is intended for the in vitro rapid identification (ID) and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram negative aerobic and facultative anaerobic bacteria belonging to the family Enterobacteriaceae and non-Enterobacteriaceae.
The BD Phoenix™ Automated Microbiology System (Phoenix System) is an automated system for the rapid identification (ID) and antimicrobial susceptibility testing (AST) of clinically relevant bacterial isolates. The system includes the following components:
- . BD Phoenix instrument and software.
- . BD Phoenix panels containing biochemicals for organism ID testing and antimicrobial agents for AST determinations.
- . BD Phoenix ID Broth used for performing ID tests and preparing AST Broth inoculum.
- . BD Phoenix AST Broth used for performing AST tests only.
- . BD Phoenix AST Indicator solution added to the AST Broth to aid in bacterial growth determination.
The Phoenix panel is a sealed and self-inoculating molded polystyrene tray with 136 micro-wells containing dried reagents. Organisms for susceptibility testing must be a pure culture and preliminarily identified as a Gram-negative or Gram-positive isolate. Phoenix panels are inoculated with a specified organism density and placed into the instrument. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD PhoenixTM AP System.
The Phoenix AST method is a broth based microdilution test. The Phoenix System utilizes a redox indicator for the detection of organism growth in the presence of an antimicrobial agent. Measurements of changes to the indicator as well as bacterial turbidity are used in the determination of bacterial growth. Each AST panel configuration contains several antimicrobial agents with a wide range of two-fold doubling dilution concentrations.
The instrument houses the panels where they are continuously incubated at a nominal temperature of 35 ℃ ± 1 °C. The instrument takes readings of the panels every 20 minutes. The readings are interpreted to give an identification of the isolate, minimum inhibitory concentration (MIC) values and category interpretations, S, I, R or N (susceptible, intermediate, resistant or not susceptible).
The provided text describes the performance study for the BD Phoenix Automated Microbiology System - GN Ceftaroline (0.0156-4 ug/mL). This system is designed for the rapid identification and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of Gram-negative bacteria.
Here's an analysis of the acceptance criteria and the study that proves the device meets them:
1. A table of acceptance criteria and the reported device performance:
The document implicitly refers to performance criteria for Essential Agreement (EA) and Category Agreement (CA) as set forth in the FDA guidance document, "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems." While specific numerical acceptance criteria (e.g., "must achieve >90% EA") are not explicitly stated as "acceptance criteria" directly in the provided text, the reported performance is compared against the CLSI reference method to demonstrate substantial equivalence. For AST systems, typical FDA expectations are generally high agreement rates.
| Performance Metric | Acceptance Criteria (Implied by Regulatory Guidance) | Reported Device Performance (Ceftaroline) |
|---|---|---|
| Essential Agreement (EA) | High agreement with reference method | 94.6% |
| Category Agreement (CA) | High agreement with reference method | 96.1% |
| Reproducibility | >95% (± 1 dilution) agreement across sites | Greater than 95% (± 1 dilution) agreement |
2. Sample size used for the test set and the data provenance:
- Test Set Sample Size: The number of isolates tested for Essential Agreement (EA) and Category Agreement (CA) was 987 (n=987) for clinical and challenge isolates combined.
- Data Provenance: The data was collected from multiple geographically diverse sites across the United States. The study included clinical, stock, and challenge isolates. This indicates a combination of real-world clinical samples, laboratory-maintained stock cultures, and specific challenge strains designed to test the limits of the system. The study appears to be prospective in nature, as it describes actively testing isolates to demonstrate performance.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
The document does not specify the number of experts or their qualifications for establishing the ground truth. It states that Phoenix System results for clinical isolates were compared to the results obtained from the CLSI reference broth microdilution method. This method itself serves as the gold standard, and the interpretation would typically follow CLSI guidelines by trained laboratory personnel, but no specific "experts" for ground truth establishment are detailed here.
4. Adjudication method for the test set:
The document does not describe an adjudication method for discrepancies. The device's results are directly compared to the CLSI reference broth microdilution method. Deviations form the basis of the EA and CA calculations.
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:
This is not an MRMC comparative effectiveness study. The device is an automated system for antimicrobial susceptibility testing, not an AI-assisted diagnostic tool for human readers. Therefore, the concept of improving human reader performance with AI assistance is not applicable here. The device itself performs the interpretation.
6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done:
Yes, a standalone performance study was done. The entire evaluation focuses on the performance of the "BD Phoenix™ Automated Microbiology System" itself (which includes the instrument, software, and panels) in determining antimicrobial susceptibility. The results (MIC values and category interpretations S, I, R, or N) are generated directly by the system based on its automated readings and algorithms. This is an "algorithm only" performance, as the system provides the final interpretive results without requiring human interpretation of raw data beyond initial organism setup.
7. The type of ground truth used:
The ground truth used for performance comparison was the CLSI reference broth microdilution method results. For challenge isolates, results were compared to "expected results," which would also be derived from a validated reference method or known characteristics of the challenge strains.
8. The sample size for the training set:
The document does not explicitly state the sample size for the training set. This document describes the "performance studies" for the pre-developed device, not the development or training of the underlying algorithms. Automated Microbiology Systems are typically developed and validated using extensive in-house datasets, but those details are not usually part of a 510(k) summary focused on post-development performance evaluation.
9. How the ground truth for the training set was established:
The document does not provide information on how the ground truth for the training set was established. As mentioned above, this document focuses on the performance evaluation of the final device for regulatory submission, not its developmental history or the specifics of how its internal algorithms were initially trained and validated. It can be inferred that the training would also have involved comparison to established reference methods like CLSI broth microdilution, but no details are given.
§ 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.”