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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.

This premarket notification is for the addition of the antimicrobial agent piperacillin-tazobactam at concentrations of 1/4-128/4 ug/mL to Gram Positive ID/AST or AST only Phoenix panels. Piperacillin-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:
Staphylococcus aureus (excluding methicillin and oxacillin-resistant isolates)

Active In Vitro Against:
Enterococcus faecalis (ampicillin or penicillin-susceptible isolates only) Staphylococcus epidermidis (excluding methicillin and oxacillin-reistant isolates)

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 t or 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 in the instrument.

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 summary of the acceptance criteria and study details for the BD Phoenix™ Automated Microbiology System for piperacillin-tazobactam:

1. Acceptance Criteria and Device Performance

2. Sample Size and Data Provenance

• Test Set Sample Size: "1949" isolates were tested for the Piperacillin-tazobactam drug. The text also mentions a "panel of Gram-positive isolates" for reproducibility studies, but a specific number for that panel isn't provided beyond discussing the clinical and challenge isolates.
• 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 and some clinical) and prospective (new clinical isolates) data collection.

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

• The document does not explicitly state the number of experts used to establish ground truth.
• It refers to "CLSI reference broth microdilution method" and "expected results" for challenge isolates as the ground truth. While these methods are performed by trained personnel, the document doesn't detail the qualifications of individuals performing these reference methods for this specific study.

4. Adjudication Method (Test Set)

• The document does not describe an adjudication method for disagreements between the device and the reference method or discrepancies amongst multiple expert readers. The comparison is directly between the Phoenix System's results and the CLSI reference method or expected results.

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

• No MRMC comparative effectiveness study was done. This study focuses on the performance of the automated system against a reference method, not on human reader performance with or without AI assistance.

6. Standalone (Algorithm Only) Performance Study

• Yes, a standalone performance study was done. The entire study describes the performance of the BD Phoenix™ Automated Microbiology System (an algorithm-driven automated device) in determining antimicrobial susceptibility. It compares the device's output directly to the CLSI reference broth microdilution method.

7. Type of Ground Truth Used

• Clinical Isolates: The ground truth for clinical isolates was the CLSI reference broth microdilution method.
• Challenge Isolates: The ground truth for challenge isolates was their expected results.

8. Sample Size for the Training Set

• The document does not explicitly state the sample size for a training set. This is a 510(k) submission focusing on substantial equivalence testing of a specific antimicrobial agent for an already established system. The underlying algorithms would have been developed and trained using data prior to this specific submission.

9. How Ground Truth for the Training Set Was Established

• The document does not provide details on how the ground truth for any training set was established. As mentioned above, this submission concerns the addition of a new antimicrobial agent to an existing system, rather than the initial development and training of the system's core algorithms.

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