(47 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 Grampositive 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-Enteriaceae 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 ciprofloxacin at concentrations of 0.125-4 ug/mL to Gram-negative ID/AST or AST only Phoenix panels. Ciprofloxacin 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.
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 Ciprofloxacin, based on the provided text:
1. Acceptance Criteria and Reported Device Performance
The device performance is assessed using Essential Agreement (EA) and Category Agreement (CA) between the BD Phoenix System and the NCCLS reference broth microdilution method.
| Acceptance Criteria (Implied by FDA Guidance) | Reported Device Performance (Table 1) |
|---|---|
| High Essential Agreement (EA) | 98.3% EA |
| High Category Agreement (CA) | 96.0% CA |
Explanation of Criteria:
- Essential Agreement (EA): Occurs when the BD Phoenix™ Automated Microbiology System's Minimum Inhibitory Concentration (MIC) result agrees exactly or within ± one two-fold dilution to the reference result.
- Category Agreement (CA): Occurs when the BD Phoenix™ Automated Microbiology System's categorical interpretation (Susceptible, Intermediate, or Resistant) agrees with the reference method's interpretation, based on FDA categorical interpretive criteria.
2. Sample Size and Data Provenance
- Test Set Sample Size (n): 2398 isolates (as indicated in Table 1 for both EA and CA).
- Data Provenance: Clinical, stock, and challenge isolates were tested across multiple geographically diverse sites across the United States. This indicates a mix of retrospective (stock/challenge) and prospective (clinical) data, primarily from the US.
3. Number of Experts and Qualifications for Ground Truth
The document does not explicitly state the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience") used to establish the ground truth for the test set. However, the ground truth is established by comparing the Phoenix System results to the NCCLS reference broth microdilution method and "expected results" for challenge isolates. The NCCLS method itself is an established standard, implying that the expertise is embedded in the standardized procedure and its interpretation, rather than individual expert adjudication per case within the study.
4. Adjudication Method
No explicit adjudication method (like 2+1 or 3+1) is mentioned. The comparison is made against the NCCLS reference broth microdilution method for clinical isolates and "expected results" for challenge isolates. This suggests a direct comparison to a gold standard or predefined expected outcome rather than a consensus-based adjudication process among multiple human readers for each test case.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No MRMC comparative effectiveness study was mentioned. The study compares an automated device (BD Phoenix) against a reference laboratory method (NCCLS broth microdilution), not against human readers. Therefore, there is no effect size reported for human readers improving with or without AI assistance.
6. Standalone Performance (Algorithm Only)
Yes, a standalone performance study was done. The entire study focuses on the performance of the BD Phoenix™ Automated Microbiology System (an algorithm/device without human-in-the-loop during the actual susceptibility testing phase) compared to the reference method.
7. Type of Ground Truth Used
The ground truth used is:
- NCCLS reference broth microdilution method for clinical isolates.
- Expected results for challenge isolates.
This represents a well-established, standardized laboratory method and predefined outcomes for known strains, which are considered the gold standard for antimicrobial susceptibility testing.
8. Sample Size for the Training Set
The document does not provide information on the sample size used for the training set. The descriptions focus on the validation studies performed to demonstrate equivalence.
9. How Ground Truth for the Training Set was Established
The document does not provide information on how the ground truth for an internal training set would have been established for the device's development. It focuses on the external validation against established reference methods for the purpose of demonstrating substantial equivalence.
§ 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.”