(55 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 antimicrobial agent tetracycline at concentrations of 0.5-16 µg/mL to Gram-negative ID/AST or AST only Phoenix panels. Tetracycline 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 species
Escherichia coli
Enterobacter aerogenes
Klebsiella species
Shigella 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 summary of the acceptance criteria and the study that proves the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance (Tetracycline) |
|---|---|---|
| Essential Agreement (EA) | Substantially equivalent to NCCLS reference method | 96.1% (n=1602) |
| Category Agreement (CA) | Substantially equivalent to NCCLS reference method | 92.3% (n=1602) |
| Intra-site Reproducibility | Greater than 90% | Greater than 90% |
| Inter-site Reproducibility | Greater than 95% | Greater than 95% |
Note: The document states that performance was assessed by calculating Essential Agreement (EA) and Category Agreement (CA) and comparing them to expected/reference results. The "Substantially equivalent" phrasing implies that the observed performance (96.1% EA and 92.3% CA) met the FDA's criteria for substantial equivalence to the reference method as outlined in the "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices".
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size: 1602 isolates (for Essential and Category Agreement).
- For site reproducibility, a "panel of Gram-negative isolates" was used, but a specific number is not provided.
- Data Provenance: Clinical, stock, and challenge isolates were tested across multiple geographically diverse sites across the United States. This indicates a prospective collection of data from various real-world settings.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications of Those Experts
The document does not explicitly state the number of experts or their qualifications 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. The NCCLS method is a standardized laboratory procedure, not typically an expert consensus.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method involving experts. The comparison was made against the "NCCLS reference broth microdilution method" and "expected results," which are standardized and objective measurements.
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
No, an MRMC comparative effectiveness study involving human readers and AI assistance was not mentioned. This device is an automated system for antimicrobial susceptibility testing; it does not involve human readers interpreting AI outputs in the way a diagnostic imaging AI might.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
Yes, the studies described are essentially standalone performance evaluations of the BD Phoenix™ Automated Microbiology System. The device itself (instrument and software) determines identification, MIC values, and category interpretations. Its output is directly compared against a reference method (NCCLS microdilution). There is no mention of human-in-the-loop performance influencing the primary results reported.
7. The Type of Ground Truth Used
- For clinical isolates: The ground truth was established by the NCCLS reference broth microdilution method. This is a laboratory-based, standardized, and widely accepted "gold standard" for antimicrobial susceptibility testing.
- For challenge isolates: The ground truth was based on "expected results." This typically refers to isolates with known susceptibility profiles.
8. The Sample Size for the Training Set
The document does not provide information on the sample size used for the training set of the BD Phoenix™ system's underlying algorithms. The study focuses solely on the performance evaluation of the already developed system.
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 it only details the performance evaluation study.
§ 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.”