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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.

The BD Phoenix™ Automated Microbiology System is intended for in vitro quantitative determination of antimicrobial susceptibility (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 the addition of the antimicrobial agent Ceftriaxone at concentrations of 0.0625-4 ug/mL to Streptococcus ID/AST or AST only Phoenix panels. Ceftriaxone has been shown to be active clinically 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. For testing Streptococcus species the system includes the following components:

• BD Phoenix instrument and software. .
• BD Phoenix panels containing biochemicals for organism ID testing and antimicrobial agents . or AST determinations.
• BD Phoenix ID Broth used for performing ID tests and preparing AST Broth inoculum. .
• BD Phoenix AST-S Broth used for performing AST tests only. .
• BD Phoenix AST-S 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 I no i novel reagents. Organisms for susceptibility testing must be a pure culture and oonlianing arree rugedive or 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. marculer for the actioners 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, R or N (susceptible, intermediate, resistant or not susceptible).

Here's an analysis of the provided text, outlining the acceptance criteria and study details for the BD Phoenix™ Automated Microbiology System - Ceftriaxone 0.0625-4 ug/mL.

1. Table of Acceptance Criteria and Reported Device Performance

The document implicitly defines acceptance criteria through its comparison to the CLSI reference method. The key performance indicators are Essential Agreement (EA) and Category Agreement (CA). While explicit percentage thresholds for acceptance aren't provided in the "Acceptance Criteria" column, the document states "substantially equivalent performance" and shows high agreement rates, implying these rates met the FDA's criteria, which are typically defined in guidance documents like the one referenced.

2. Sample Size Used for the Test Set and Data Provenance

• Test Set Sample Size: 2013 isolates for the Essential Agreement (EA) and Category Agreement (CA) analysis.
• Data Provenance: Clinical, stock, and challenge isolates were tested across multiple geographically diverse sites. The study design is prospective in nature, comparing the investigational device to a reference method, mimicking a clinical setting for the "clinical isolates" portion.

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

The document does not specify the number of experts or their qualifications used to establish the ground truth. It states that the Phoenix System results were compared to the CLSI reference broth microdilution method. This method itself is a standardized laboratory procedure, and adherence to it is the primary "ground truth" for susceptibility testing, rather than expert interpretation of results.

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 automated system's output and the standardized CLSI reference method. Discrepancies would likely be investigated within the framework of the CLSI method's established quality control and interpretation guidelines.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance?

No. This study is a standalone performance comparison of an automated system against a reference method. It does not involve human readers, nor does it assess the improvement of human readers with or without AI assistance. The BD Phoenix™ system is an automated device, not an AI-assisted diagnostic tool for human interpretation.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, a standalone study was done. The entire evaluation described in the "Clinical Studies" section compares the BD Phoenix™ Automated Microbiology System (an automated device/algorithm) directly to the CLSI reference broth microdilution method. This evaluates the system's performance without human intervention in the interpretation process once the system has processed the sample.

7. The Type of Ground Truth Used

The primary ground truth used is the CLSI reference broth microdilution method. This is a well-established, standardized laboratory method for determining antimicrobial susceptibility, considered the gold standard for AST. For "Challenge set isolates," the ground truth was "expected results," implying predefined, known susceptibility profiles for those specific isolates.

8. The Sample Size for the Training Set

The document does not specify a separate training set or its sample size. This is common for automated diagnostic systems like this, where the "training" (development and calibration) of the internal algorithms for identifying MICs and categories would have occurred during the system's initial development and prior to these validation studies. The studies described are primarily for validation and regulatory submission.

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

Since a dedicated training set is not explicitly mentioned, the document does not detail how its ground truth was established. However, based on the nature of the device, the ground truth for any internal development and calibration would typically be established using CLSI reference broth microdilution methods or similar gold standard laboratory techniques, performed by trained microbiologists.

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