(30 days)
The BD Phoenix™ Automated Microbiology System is intended for the rapid identification and in vitro antimicrobial susceptibility testing of isolates from pure culture of most aerobic and facultative anaerobic Gram-negative and Gram-positive bacteria of human origin.
The BD Phoenix™ Automated Microbiology System is intended for in vitro quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram-negative aerobic and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and Non-Enterobacteriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus and Enterococcus.
This premarket notification is for the addition of the antimicrobjal agent Tobramycin at concentrations of 0.125-16 ug/mL to Gram-negative ID/AST cr AST only Phoenix panels. Tobramycin has been shown to be active in vitro against most strains of microorganisms listed below, as described in the FDA-approved package insert for this antimicrobial agent.
Active In Vitro and in Clinical Infections Against:
- Citrobacter species Enterobacter species Escherichia coli Klebsiella species Morganella morganii
Pseudomonas aeruginosa Proteus mirabilis Proteus vulgaris Providencia species (excluding Providencia stuartii) Serratia species
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. For each isolate, an inoculation equivalent to a 0.5 McFarland standard is prepared in Phoenix ID Broth.
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°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, or R (sensitive, intermediate, or resistant).
Here's a breakdown of the acceptance criteria and study information for the BD Phoenix™ Automated Microbiology System for Tobramycin, based on the provided text:
Acceptance Criteria and Device Performance Study for BD Phoenix™ Automated Microbiology System Tobramycin
1. Table of Acceptance Criteria and Reported Device Performance
The study evaluated two primary performance metrics: Essential Agreement (EA) and Category Agreement (CA). The acceptance criteria are based on those outlined in the FDA Draft Guidance Document, "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices", March 8, 2000. While the exact numerical criteria from the guidance document are not explicitly stated in the provided text, the document indicates that the system "demonstrated substantially equivalent performance" when compared to the NCCLS reference method. Typically, acceptable Essential Agreement (EA) is generally >90% and acceptable Category Agreement (CA) is generally >90%, with specific allowances for minor discrepancies.
| Metric | Acceptance Criteria (Implied by FDA Guidance) | Reported Device Performance (Tobramycin for Gram-negative organisms) |
|---|---|---|
| Essential Agreement (EA) | Substantially Equivalent to Reference (>90%) | 92.2% |
| Category Agreement (CA) | Substantially Equivalent to Reference (>90%) | 95.0% |
Note: The actual acceptance criteria percentages from the FDA guidance are not directly stated, but "substantially equivalent performance" implies meeting or exceeding recognized performance thresholds, typically >90% for both EA and CA in AST device evaluations.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set: 2658 isolates (n=2658 for both EA and CA calculations).
- Data Provenance: Clinical, stock, and challenge isolates were tested across multiple geographically diverse sites across the United States. The clinical isolates were compared to the NCCLS reference broth microdilution method, while challenge set isolates were compared to expected results.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The document does not explicitly state the number or qualifications of experts used to establish the ground truth. It refers to the NCCLS reference broth microdilution method as the comparator for clinical isolates and "expected results" for challenge isolates. This implies that the ground truth was established by laboratory personnel following standardized NCCLS protocols, which are expert-driven methodologies, rather than individual expert adjudication of pre-existing images or data.
4. Adjudication Method for the Test Set
Not applicable in the traditional sense of multiple human readers adjudicating an output. The "ground truth" for clinical isolates was the NCCLS reference broth microdilution method, which is a standardized laboratory procedure, not an adjudication process requiring multiple human experts to resolve discrepancies. For challenge isolates, results were compared to "expected results," which are predefined.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This study focuses on the standalone performance of the automated system compared to a reference method, not on how the system assists human readers.
6. Standalone Performance Study
Yes, a standalone performance study was done. The BD Phoenix™ Automated Microbiology System's performance was directly compared to the NCCLS reference broth microdilution method and expected results for challenge isolates, without a human-in-the-loop component.
7. Type of Ground Truth Used
- Clinical Isolates: The ground truth was established by the NCCLS reference broth microdilution method.
- Challenge Isolates: The ground truth was established by expected results.
8. Sample Size for the Training Set
The document does not specify a separate "training set" or its sample size. The study describes "Clinical, stock and challenge isolates" used for performance evaluation, but does not detail a distinct training phase. This type of device (Antimicrobial Susceptibility Testing system) typically relies on pre-programmed algorithms based on known biological responses rather than machine learning models that require distinct training and test sets in the same way an image recognition AI might.
9. How the Ground Truth for the Training Set Was Established
As no explicit training set is described in the provided text, the method for establishing its ground truth is not available. The system's underlying technology would have been developed based on extensive microbiological principles and data, but the text focuses on the validation of the specific device and antimicrobial agent.
§ 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.”