(28 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.
This premarket notification is for the addition of the antimicrobial agent Amikacin at concentrations of 0.5-64 ug/mL to Gram Negative ID/AST or AST only Phoenix panels. Amikacin 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:
Acinetobacter spp. Citrobacter freundii Enterobacter spp. Escherichia coli Klebsiella spp. Proteus spp. Providencia spp. Pseudomonas spp. Serratia spp.
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 an analysis of the provided text regarding the acceptance criteria and the study proving the device meets those criteria:
Acceptance Criteria and Device Performance Study for BD Phoenix™ Automated Microbiology System - Amikacin
1. Table of Acceptance Criteria and Reported Device Performance
| Metric | Acceptance Criteria | Reported Device Performance (Amikacin) |
|---|---|---|
| Site Reproducibility (Intra-site) | Greater than 90% reproducibility for the antimicrobial agent | Greater than 90% |
| Site Reproducibility (Inter-site) | Greater than 95% reproducibility for the antimicrobial agent | Greater than 95% |
| Essential Agreement (EA) | Not explicitly stated as a numerical threshold in the provided text, but implied to be "substantially equivalent" to the NCCLS reference method. Typically, this is 90% or higher for AST devices. | 95.3% (n=2598) |
| Category Agreement (CA) | Not explicitly stated as a numerical threshold in the provided text, but implied to be "substantially equivalent" to the NCCLS reference method. Typically, this is 90% or higher for AST devices. | 96.7% (n=2598) |
Note: The document states that performance was evaluated as defined in the FDA Draft guidance document, "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices", March 8, 2000. While explicit numerical acceptance criteria for EA and CA are not present in the provided text, the reported values are in line with what is generally considered acceptable for "substantially equivalent" AST devices (typically >90%).
2. Sample Size and Data Provenance
- Test Set Sample Size:
- Clinical Isolates: 2598 (based on the 'n' value in the EA and CA performance table for Amikacin).
- Stock and Challenge Isolates: The exact number is not explicitly stated, but they were also included in the overall clinical study alongside clinical isolates.
- Data Provenance: The study was conducted across "multiple geographically diverse sites across the United States." The data is prospective, generated specifically for this study.
3. Number of Experts and Qualifications for Ground Truth
The document does not explicitly state the number or qualifications of experts used to establish the ground truth. However, the ground truth for clinical isolates was established by the NCCLS reference broth microdilution method. This method itself is a standardized, expert-approved laboratory procedure, implicitly relying on the expertise of trained microbiologists to perform and interpret. For challenge isolates, "expected results" were used, implying pre-established, known resistance/susceptibility profiles.
4. Adjudication Method for the Test Set
The document does not mention an adjudication method (like 2+1, 3+1, etc.) for the test set. The comparison for clinical isolates was directly against the NCCLS reference method, and for challenge isolates, against expected results. This suggests direct comparison rather than a human consensus-based adjudication process for the device's output.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No. This study is not an MRMC comparative effectiveness study involving human readers. It evaluates the performance of an automated device against a reference method, not an AI's impact on human reader effectiveness.
6. Standalone Performance Study
Yes, this is a standalone performance study. The BD Phoenix™ Automated Microbiology System is an algorithm-only (automated device) without human-in-the-loop performance being a primary endpoint or evaluation criterion. Its results (MIC values and categorical interpretations) are compared directly to a gold standard.
7. Type of Ground Truth Used
- Clinical Isolates: NCCLS reference broth microdilution method.
- Challenge Isolates: "Expected results," which are typically pre-determined susceptibility profiles for known strains, often established by reference laboratories or expert panels.
8. Sample Size for the Training Set
The document does not provide information on the sample size used for the training set. This is typical for medical device submissions that focus on the validation (test set) performance for regulatory clearance, often assuming the training and development were internal and proprietary.
9. How the Ground Truth for the Training Set was Established
The document does not specify how the ground truth for the training set (if any explicit training was done for an underlying algorithm) was established. Given the nature of the device (an automated microbiology system based on physical and chemical reactions), the "training" might be less about a deep learning model's training data and more about the extensive development and calibration of the instrument and its reagent panels using known bacterial strains and reference methods.
§ 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.”