(50 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, Enterococcus, and Streptococcus.
This premarket notification is for additional organism groups and BD Phoenix™ Automated Microbiology System with cefepime (0.5-64 µg/mL) and ceftriaxone (0.5-64 µg/mL) on Gramnegative ID/AST or AST only Phoenix panels.
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 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 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.
The instrument houses the panels where they are continuously incubated at a nominal temperature of 35℃. 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).
1. Acceptance Criteria and Reported Device Performance
| Antimicrobial | Acceptance Criteria (FDA Guidance 2003) | Device Performance (Essential Agreement, EA%) | Device Performance (Category Agreement, CA%) |
|---|---|---|---|
| Cefepime | N/A (Guidance sets thresholds) | 95.2% | 92.9% |
| Ceftriaxone | N/A (Guidance sets thresholds) | 95.8% | 90.9% |
Note: The document references the "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems: Guidance for Industry and FDA," February 5, 2003. While specific numerical acceptance criteria for EA and CA are not explicitly stated in the provided text, such guidance documents typically define thresholds for these metrics to demonstrate substantial equivalence. The reported performance metrics are then compared against these implied or explicit thresholds.
2. Sample Size Used for the Test Set and Data Provenance
The exact sample size for the test set is not explicitly stated as a single number. Instead, the number of isolates for which Essential Agreement (EA) and Category Agreement (CA) were calculated for each antimicrobial agent are provided.
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Cefepime: 1789 isolates for EA and CA.
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Ceftriaxone: 1872 isolates for EA and CA.
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Data Provenance: Clinical, stock, and challenge isolates were tested from "multiple geographically diverse sites across the United States." This indicates a prospective collection of data from diverse US locations.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not specify the number of experts or their qualifications used to establish the ground truth. It states that Phoenix System results for clinical isolates were compared to results obtained from the CLSI reference broth microdilution method. While this method is a well-established standard, it doesn't explicitly involve a panel of human experts for ground truth establishment in the same way, for instance, a radiological image interpretation study would.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method involving multiple readers or a specific consensus process. The comparison is made directly between the BD Phoenix System results and the CLSI reference broth microdilution method.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not explicitly done or described in the provided text. The study focused on comparing the automated system's performance against a reference method rather than assessing human reader improvement with or without AI assistance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, a standalone performance evaluation was done. The study directly assessed the performance of the "BD Phoenix™ Automated Microbiology System" (the device/algorithm) against the CLSI reference broth microdilution method. This represents the algorithm's performance without direct human intervention in the result determination process for the tested isolates.
7. The Type of Ground Truth Used
The ground truth used was the CLSI reference broth microdilution method. This is considered the gold standard for antimicrobial susceptibility testing. For challenge set isolates, the Phoenix System results were compared to "expected results," which would also be derived from established methods 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 a "training set." The study described is an evaluation of the system's performance for new antimicrobial agents (Cefepime and Ceftriaxone) and additional organism groups. It's an assessment of the developed system, not a description of its initial development or training.
9. How the Ground Truth for the Training Set Was Established
Since a dedicated training set is not explicitly mentioned or detailed, the method for establishing its ground truth is not provided. Assuming the system was "trained" or developed based on established microbiology principles and possibly internal datasets, those datasets would have likely used the CLSI reference broth microdilution method or similar validated gold standards to establish ground truth during the system's development.
§ 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.”