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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 a modification of the algorithm for Vancomycin (0.5-32 ug/mL) with Enterococcus species and Staphylococcus species and updates for software from the last software cleared by FDA under K040099 through version 6.01.

Vancomycin 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:

Enterococci (e.g., Enterococcus faecalis)

Staphylococci, including Staphylococcus aureus and Staphylococcus epidermidis (including heterogeneous methicillin-resistant strains).

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° ± 19C. 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).

BD Phoenix™ Automated Microbiology System Vancomycin (VA_18, 0.5-32 µg/mL) - GP and Phoenix Instrument SW Update through Version 6.01

1. Acceptance Criteria and Reported Device Performance:

2. Sample Size for Test Set and Data Provenance:

• Sample Size: The clinical studies report an "n" of 1538 for both Essential Agreement (EA) and Category Agreement (CA) for Vancomycin (0.5-32 µg/mL). This represents the total number of isolates tested in the clinical and challenge sets.
• Data Provenance: The isolates were tested "across multiple geographically diverse sites across the United States." The study included "Clinical, stock and challenge isolates," indicating a mix of retrospective (stock/challenge could represent archived isolates) and prospective (clinical isolates collected during the study) data.

3. Number of Experts Used to Establish Ground Truth for Test Set and Qualifications:

The document does not explicitly state the number of experts or their specific qualifications. However, it mentions that the Phoenix System results for clinical isolates were compared to the results obtained from the CLSI reference broth microdilution method. This implies that the CLSI method, which is a standardized and widely accepted laboratory procedure, served as the ground truth. The execution and interpretation of this reference method would inherently involve trained microbiologists or laboratory technicians, who can be considered experts in their field.

4. Adjudication Method for the Test Set:

The document does not describe an explicit adjudication method involving multiple human readers for discrepancies. The comparison is primarily between the BD Phoenix System results and the CLSI reference broth microdilution method. Deviations would likely be analyzed based on the established accuracy and precision of the reference method and the Phoenix system's performance metrics (EA, CA).

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study focusing on human reader improvement with AI assistance was not performed. This study is an evaluation of an automated antimicrobial susceptibility testing system, not an AI-assisted diagnostic tool for human interpretation.

6. Standalone (Algorithm Only) Performance:

Yes, a standalone performance study was done. The entire study describes the performance of the BD Phoenix™ Automated Microbiology System, which is an algorithm-driven device, in determining antimicrobial susceptibility. The Essential Agreement (EA) and Category Agreement (CA) values reported (99.0% and 99.6% respectively) represent the standalone performance of the algorithm without human intervention in the interpretation of the results from the Phoenix system.

7. Type of Ground Truth Used:

The primary ground truth used was the CLSI reference broth microdilution method. For the "Challenge set isolates," the Phoenix System results were compared to "expected results," which would also be derived from established reference methods or known antimicrobial profiles of the challenge organisms. The CLSI method is a well-established and accepted laboratory gold standard for antimicrobial susceptibility testing.

8. Sample Size for the Training Set:

The document does not provide a specific sample size for a "training set." This submission is for a modification of an existing algorithm and a software update. The existing algorithm was likely developed and "trained" on a large dataset over time. The current study focuses on demonstrating the performance of the modified algorithm and software against a clinical and challenge test set.

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

As no specific "training set" and its ground truth establishment are detailed in this document, it's inferred that the initial development and "training" of the BD Phoenix system's algorithms would have relied on extensive data generated through established reference methods, such as the CLSI broth microdilution method, from a wide variety of bacterial isolates and antimicrobial agents. This iterative process of development, testing against reference standards, and refinement would have established the ground truth for the underlying algorithms.

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