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The BD PhoenixTM 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 by minimal inhibitory concentration (MIC) of most Gram-negative and facultative anaerobic bacteria isolates from pure culture for Emero Cram-Regarter accedes and and most Gram-positive bacteria isolates from pure culture belonging to the genera Stanylococcuses , Enterococcus, and Streptococcus.
This premarket notification is for the addition of the antimicrobial agent trimethoprim-sulfamethoxazole at concentrations of 0.0625/1.2-16/304 ug/mL to Streptococcus ID/AST or AST only Phoenix panels. Trimethoprimsulfamethoxazole has been shown to be active in vitro against most strains of microrganisms listed below, as described in the FDA-approved package insert for this antimicrobial agent.
Active In Vitro and in Clinical Infections Against: Streptococcus pneumoniae

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.
• of TLS Forethinations: .
• 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 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, R or N (susceptible, intermediate, resistant or not susceptible).

Acceptance Criteria and Device Performance for BD Phoenix™ Automated Microbiology System - Trimethoprim-sulfamethoxazole

This document describes the acceptance criteria and the study that demonstrates the BD Phoenix™ Automated Microbiology System, specifically with Trimethoprim-sulfamethoxazole (0.0625/1.2-16/304 µg/mL) and Streptococcus ID/AST or AST only Phoenix Panels, meets these criteria.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are derived from the FDA Draft guidance document, "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA," February 5, 2003, for establishing substantial equivalence to a reference method (CLSI broth microdilution). While specific numerical acceptance thresholds are not explicitly stated in the provided text, the criteria are implicitly demonstrated by achieving "substantially equivalent performance" and high agreement rates.

2. Sample Size and Data Provenance for Test Set

• Sample Size: The test set for accuracy (Essential Agreement and Category Agreement) included 906 isolates for Trimethoprim-sulfamethoxazole. This combined "clinical, stock and challenge isolates."
• Data Provenance: The isolates were tested across "multiple geographically diverse sites across the United States." The study included "clinical, stock and challenge isolates." The clinical isolates were compared to the CLSI reference broth microdilution method, while challenge isolates "were compared to the expected results." This indicates a mix of retrospective and prospective data, with clinical isolates likely representing prospective collection for the study, and stock/challenge isolates being pre-existing.

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

The document does not explicitly state the number or specific qualifications of experts used to establish the ground truth for the test set. It refers to the CLSI reference broth microdilution method as the "reference method" for clinical isolates and "expected results" for challenge isolates. This implies that the CLSI method itself, including its standard operating procedures and trained personnel, served as the "expert" ground truth.

4. Adjudication Method (Test Set)

The document does not describe an explicit adjudication method (e.g., 2+1, 3+1). The comparison is directly made between the BD Phoenix System results and the CLSI reference broth microdilution method or "expected results" for challenge isolates. Discrepancies would likely be investigated, but a formal multi-reader adjudication process as seen in imaging studies is not applicable here.

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

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This type of study is typical for diagnostic imaging devices where human readers interpret results, and the AI's role is to assist these readers. This device is an automated microbiology system that performs the test and provides results automatically; it does not involve human interpretation that is then assisted by AI in the traditional sense.

6. Standalone Performance Study

Yes, a standalone performance study was done. The entire study described is a standalone performance evaluation of the BD Phoenix™ Automated Microbiology System. The device, without human-in-the-loop interpretation of the primary reading, directly produces Minimum Inhibitory Concentration (MIC) values and categorical interpretations (S, I, R, N). Its performance (Essential Agreement and Category Agreement) is compared against a reference standard (CLSI broth microdilution method), demonstrating its accuracy as a standalone system.

7. Type of Ground Truth Used

The primary ground truth used for clinical isolates was the CLSI reference broth microdilution method. For challenge isolates, "expected results" were used. The CLSI method is a well-established and accepted laboratory gold standard for antimicrobial susceptibility testing, involving the precise measurement of bacterial growth inhibition at various antimicrobial concentrations. This is a form of objective, highly standardized laboratory measurement.

8. Sample Size for the Training Set

The document does not specify the sample size for the training set. The provided text focuses on the performance evaluation (test set) for the specific antimicrobial agent and organism. Automated systems like the BD Phoenix™ are often developed using large, diverse internal datasets over time, but details of the training data for this specific component are not given.

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

The document does not describe how the ground truth for the training set was established. Similar to the sample size, the specifics of the training data development and ground truth establishment for the underlying algorithm of the BD Phoenix System are not provided in this 510(k) summary. It can be inferred that similar reference methods (like CLSI broth microdilution) would have been used during the development and training phases of the system to establish the accuracy and reliability of its automated interpretations.

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