(31 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 meropenem at concentrations of 0.25-16 ug/mL to Gram-negative ID/AST or AST only Phoenix panels. meropenem 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:
Escherichia coli
Klebsiella pneumoniae
Pseudomonas aeruginosa
Active In Vitro Against:
Acinetobacter species
Aeromonas hydrophila
Citrobacter koseri
Citrobacter freundii
Enterobacter cloacae
Hafnia alvei
Klebsiella oxytoca
Morganella morganii
Proteus mirabilis
Proteus vulgaris
Salmonella species
Serratia marcescens
Shigella species
Yersinia enterocolitica
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).
Acceptance Criteria and Study for BD Phoenix™ Automated Microbiology System (Meropenem GN)
Here is a breakdown of the acceptance criteria and the study proving the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Implicit) | Reported Device Performance (Meropenem, Gram-negative) |
|---|---|
| Overall intra-site reproducibility of > 90% (for this antimicrobial agent) | > 90% |
| Overall inter-site reproducibility of > 95% (for this antimicrobial agent) | > 95% |
| Essential Agreement (EA) with reference method (defined as within +/- one two-fold dilution) | 97.6% (n=2905) |
| Category Agreement (CA) with reference method (S, I, R categories) | 98.3% (n=2905) |
| Substantial equivalence to NCCLS reference broth microdilution method and predicate devices (VITEK® System, BD Phoenix™ with Gatifloxacin, Ofloxacin, Levofloxacin) | Concluded as substantially equivalent |
Note: The document explicitly states the reproducibility criteria. The Essential Agreement (EA) and Category Agreement (CA) percentages are reported as performance metrics, and the conclusion of "substantially equivalent performance" implies these values met the internal acceptance thresholds for the study to deem it equivalent to the reference method.
2. Sample Size Used for the Test Set and Data Provenance
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Sample Size for Test Set:
- Reproducibility Studies: Not explicitly stated, but involved a "panel of Gram-negative isolates" tested in triplicate on three different days at three sites.
- Clinical Studies: 2905 instances for Essential Agreement (EA) and Category Agreement (CA) with Meropenem against Gram-negative organisms. This number represents the total successful comparisons made.
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Data Provenance: The isolates were tested across "multiple geographically diverse sites across the United States." The study included "Clinical, stock and challenge isolates."
- Retrospective/Prospective: Not explicitly stated, but the mention of "clinical isolates" usually implies prospective collection during the study period, while "stock and challenge isolates" could be historical or specifically prepared for the study.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
The document does not specify the number or qualifications of experts used to establish the ground truth.
However, the ground truth was established by:
- NCCLS reference broth microdilution method: This is a standardized laboratory protocol, not dependent on individual expert interpretation in the same way an image adjudication would be.
- Expected results for challenge isolates: This implies pre-defined and verified results for a set of known strains.
4. Adjudication Method for the Test Set
No explicit human adjudication method (like 2+1 or 3+1) was used for establishing the ground truth for the MIC values or categories. The ground truth was determined by:
- NCCLS reference broth microdilution method: This is a direct laboratory assay result.
- Expected results: For challenge isolates, the "expected results" serve as the ground truth.
Deviations from these reference methods were measured as Essential Agreement and Category Agreement.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was mentioned or performed. This device is an automated system for antimicrobial susceptibility testing, designed to perform the test without human interpretation of results in the traditional sense of a diagnostic image. Its performance is compared to a reference standard method, not human readers.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, a standalone study was performed. The entire study describes the performance of the "BD Phoenix™ Automated Microbiology System" (the algorithm/device) against a reference standard without human intervention in the result interpretation process. The device directly outputs the MIC values and categorical interpretations (S, I, R).
7. Type of Ground Truth Used
The primary ground truth used was:
- NCCLS reference broth microdilution method: For clinical isolates, the results from this gold-standard laboratory method were considered the truth.
- Expected results: For challenge isolates, pre-defined "expected results" served as the ground truth.
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 a 510(k) submission for an automated microbiology system, as the "training" (calibration and development) processes are often proprietary and not detailed in the same way as, for example, a machine learning model for image analysis. The focus here is on the system's performance after its development.
9. How the Ground Truth for the Training Set Was Established
The document does not explicitly describe how the ground truth for any potential "training set" (development/calibration data for the instrument) was established. However, given the nature of the device, it would have been established through well-defined laboratory protocols, likely also using reference methods such as the NCCLS broth microdilution method, and potentially including expert microbiological analysis during the initial development and validation phases of the system.
§ 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.”