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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 gramnegative 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 antimicrobial agent piperacillin-tazobactam at concentrations of 0.5/4-128/4 µg/mL to gram-negative 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.

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 sclution 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 Device Performance Study for BD Phoenix™ Automated Microbiology System (Piperacillin-Tazobactam)

This information is based on the provided 510(k) summary for the BD Phoenix™ Automated Microbiology System with Piperacillin-tazobactam (K042932).

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for the BD Phoenix System are based on Essential Agreement (EA) and Category Agreement (CA) when compared to the NCCLS reference broth microdilution method. While explicit percentage targets for acceptance criteria are not stated in the provided text, the FDA guidance document "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices" (March 8, 2000) and "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA" (February 5, 2003) were used to define performance evaluation, implying certain thresholds for substantial equivalence. The reported performance for gram-negative organisms with Piperacillin-tazobactam is as follows:

Note on Acceptance Criteria: The specific numerical acceptance thresholds were not explicitly stated as "acceptance criteria" in the provided text. However, the FDA guidance documents typically require high percentages for both EA and CA to demonstrate substantial equivalence. The achieved percentages (93.2% EA and 94.9% CA) were deemed sufficient for FDA clearance.

2. Sample Size and Data Provenance

• Test Set Sample Size (for Piperacillin-tazobactam with gram-negative organisms): The combined number of isolates tested in clinical studies was 1546 for both Essential Agreement (EA) and Category Agreement (CA).
• Data Provenance: The isolates tested included "Clinical, stock and challenge isolates" from "multiple geographically diverse sites across the United States." This indicates a prospective and multi-center approach for clinical isolates, supplemented with stock and challenge isolates.

3. Number of Experts and Their Qualifications for Ground Truth

The document does not explicitly state the number of experts or their specific qualifications for establishing the ground truth for the test set. However, for antimicrobial susceptibility testing, the "NCCLS reference broth microdilution method" is the established gold standard. This method itself implies standardized procedures and interpretation by trained personnel.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method for disagreements. The comparison was directly between the BD Phoenix System results and the NCCLS reference broth microdilution method.

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

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was mentioned in the provided text. The study focused on the performance of the automated device against a reference method, not on human reader performance with or without AI assistance.

6. Standalone Performance Study

Yes, a standalone performance study was conducted. The entire evaluation described in the "Summary of Substantial Equivalence Testing" and "Clinical Studies" sections assesses the performance of the BD Phoenix™ Automated Microbiology System (algorithm only, without human intervention in the interpretation phase) against the reference method. The system autonomously determines minimum inhibitory concentration (MIC) values and category interpretations (S, I, or R).

7. Type of Ground Truth Used

The ground truth used was the NCCLS reference broth microdilution method, which is a widely accepted laboratory standard for antimicrobial susceptibility testing. For "challenge set isolates," expected results were used as the ground truth.

8. Sample Size for the Training Set

The document does not provide information regarding the sample size used for the training set of the BD Phoenix Automated Microbiology System. The submission focuses on the validation of the system with a specific antimicrobial agent (Piperacillin-tazobactam) and its performance against a predicate device and reference method.

9. How Ground Truth for the Training Set Was Established

The document does not provide information on how the ground truth for the training set was established. Given the nature of the device (a commercial automated system), the training would have been conducted by the manufacturer, likely using established reference methods, but the specifics are not detailed in this 510(k) summary.

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