Search Results

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, Enterococcus and Streptococcus.

Ceftolozane/tazobactam 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: Gram-negative bacteria Enterobacter cloacae Escherichia coli Klebsiella oxytoca Klebsiella pneumoniae Proteus mirabilis Pseudomonas aeruginosa

Active In Vitro but clinical significance is unknown: Gram-negative bacteria Citrobacter koseri Morganella morganii Proteus vulgaris Providencia stuartii Serratia liquefaciens Serratia marcescens

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 PhoenixTM 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).

1. Acceptance Criteria and Reported Device Performance

Note on Vmj Error: While a significant initial Vmj error rate was noted for E. coli, the submission indicates that additional testing and replicate analysis demonstrated no Vmj errors, suggesting the device ultimately met an acceptable standard for this metric.

2. Sample Size and Data Provenance (Test Set)

• Sample Size:
  • Clinical and Challenge Isolates: 1179 isolates in total ("All Organisms" in the performance table).
    • Specifically, 1034 Enterobacteriaceae isolates.
    • Specifically, 145 Pseudomonas aeruginosa isolates.
    • An "additional comparative study" included 66 resistant E. coli isolates to further investigate very major errors.
  • Reproducibility Test: A "panel of Gram-negative isolates" was used, tested in triplicate on three different days. The exact number of isolates is not specified.
• Data Provenance: The isolates were tested "across multiple geographically diverse sites across the United States." Whether the data was purely retrospective or involved prospective collection is not explicitly stated, but "clinical, stock and challenge isolates" suggests a mix, possibly including isolates collected for the purpose of the study (prospective) and pre-existing isolates (retrospective/stock).

3. Number of Experts and Qualifications (Ground Truth for Test Set)

The document does not explicitly state the number or qualifications of experts used to establish the ground truth for the test set.

4. Adjudication Method (Test Set)

The document does not explicitly describe an adjudication method for the test set. The "ground truth" was established by comparing the device's results to the CLSI reference broth microdilution method or to "expected results" for challenge isolates. This implies a direct comparison rather than a human expert adjudication process for the final MIC values.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No. The study described is a standalone performance evaluation of an automated antimicrobial susceptibility testing (AST) system compared to a reference method, not a comparative effectiveness study involving human readers with and without AI assistance. Therefore, there is no effect size reported for human readers' improvement with AI.

6. Standalone Performance Study

Yes. The study described is a standalone performance study. The "BD Phoenix™ Automated Microbiology System" (the algorithm/device) was directly compared to the CLSI reference broth microdilution method, which served as the gold standard for establishing ground truth for antimicrobial susceptibility.

7. Type of Ground Truth Used (Test Set)

The primary type of ground truth used was:

• Reference Method Comparison: For clinical isolates, the BD Phoenix System results were compared to the results obtained from the CLSI reference broth microdilution method (AST panels prepared according to CLSI M07). This is a recognized laboratory standard.
• Expected Results: For challenge isolates, the BD Phoenix System results were compared to "expected results." These expected results are typically derived from extensive prior characterization of these specific isolates, often using reference methods or phenotypic/genotypic analysis.

8. Sample Size for the Training Set

The document does not provide information on the sample size for a training set. This is typical for an AST device evaluation, where the "training" (if it occurs) is usually part of the initial development and validation of the instrument's growth detection and MIC interpretation algorithms, and not explicitly detailed in a 510(k) submission focused on the performance of a new antimicrobial agent on an existing system. The collected data represents the test set for evaluating the performance of the system with the new drug.

9. How the Ground Truth for the Training Set Was Established

As no training set is explicitly mentioned or detailed, the method for establishing its ground truth is not provided. The entire submission focuses on the performance of the device against a defined test set where the CLSI reference method served as the ground truth.

Ask a specific question about this device