(82 days)
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 and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus. Enterococcus and Streptococcus.
This premarket notification is for the antimicrobial agent tigecycline at concentrations of 0.0313-4 ug/mL to Gram-positive ID/AST or AST only Phoenix panels. Tigecycline 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:
Enterococcus faecalis (vancomycin-susceptible isolates) Staphylococcus aureus (methicillin-susceptible and -resistant isolates)
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 Phoenix™ 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).
Here's a breakdown of the acceptance criteria and study details based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance (Tigecycline) |
|---|---|---|
| Site Reproducibility | Overall >95% agreement (+/- 1 dilution) | >95% agreement across test sites |
| Essential Agreement (EA) | Not explicitly stated, but often >/= 90-95% for AST systems | 98.0% (n=1021) |
| Category Agreement (CA) | Not explicitly stated, but often >/= 90-95% for AST systems | 100.0% (n=1021) |
Note: The acceptance criteria for Essential Agreement and Category Agreement are inferred given typical FDA guidance for AST devices but are not explicitly stated as numerical targets in the provided document.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set:
- Clinical and Challenge Isolates: 1021 (for Tigecycline with Gram-Positive organisms)
- Site Reproducibility: A "panel of Gram-positive isolates" tested in triplicate on three different days. The exact number of isolates for reproducibility is not specified, but the overall result suggests a sufficient number to meet the >95% agreement.
- 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, specifically for the purpose of this study, and from multiple locations within the United States.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
The document does not specify the number of experts or their qualifications for establishing the ground truth. It refers to "expected results" for challenge isolates and "results obtained from the CLSI reference broth microdilution method" for clinical isolates.
4. Adjudication Method for the Test Set
The document does not mention an adjudication method. The comparison for clinical isolates was directly against the CLSI reference broth microdilution method, implying this method served as the sole reference standard for comparison.
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 performance of an automated system (BD Phoenix) against a reference method (CLSI broth microdilution) for antimicrobial susceptibility testing, not on human reader performance with or without AI assistance.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, a standalone study was done. The BD Phoenix Automated Microbiology System is an automated system that provides results without direct human intervention in the interpretation process of individual wells. The study compares the results generated by this automated system to a reference method, indicating a standalone algorithm performance assessment. The "Phoenix System results" are directly compared to reference methods.
7. Type of Ground Truth Used
- For Clinical Isolates: The ground truth was established by the CLSI reference broth microdilution method (AST panels prepared according to CLSI M7).
- For Challenge Isolates: The ground truth was based on "expected results." While not explicitly defined, "expected results" for challenge isolates in microbiology studies typically refer to known, predetermined susceptibility profiles derived from expert consensus or prior extensive testing using a gold standard.
8. Sample Size for the Training Set
The document does not explicitly state the sample size for a "training set." The study described is a performance validation, comparing the device's output to a reference method. It's likely that the BD Phoenix system was developed and possibly trained on a larger, undisclosed dataset prior to this specific validation study, but that information is not provided here.
9. How the Ground Truth for the Training Set Was Established
Since the document does not discuss a specific training set or its sample size, it also does not detail how the ground truth for any training set was established.
§ 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.”