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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 Grampositive bacteria of human origin.

The BD Phoenix™ Automated Microbiology System is intended for in vitro quantitative determination of the minimum inhibitory concentration (MIC) of most Gram-negative aerobic and facultative anaerobic bacteria belonging to the family 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 amoxicillin at concentrations of 0.0313-32 ug/mL to the BD Phoenix panels. Amoxicillin has been shown to be active in vitro and in clinical infections against: Streptococcus pneumoniae, Streptococcus spp. (x-and ß-hemolytic strains only).

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 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).

Here's a breakdown of the acceptance criteria and study details for the BD PHOENIX™ Automated Microbiology System Amoxicillin - Strep, based on the provided 510(k) summary:

Acceptance Criteria and Device Performance

Study Details

1. Sample Size and Data Provenance

• Test Set Sample Size: 1027 isolates (for both EA and CA calculations).
• Data Provenance: Clinical, stock, and challenge isolates were tested across multiple geographically diverse sites across the United States. The study was prospective in nature, as new data was collected to demonstrate performance against a reference method.

2. Number of Experts to Establish Ground Truth and Qualifications

• The document does not specify the number of experts used or their qualifications to establish ground truth.
• However, the ground truth was established using the CLSI reference broth microdilution method, which is a standardized and widely accepted microbiological technique, implying that trained microbiologists performed these reference tests.

3. Adjudication Method

• The document does not explicitly state an adjudication method (like 2+1, 3+1).
• Instead, the comparison was made between the Phoenix System's results and the single, established CLSI reference broth microdilution method results. Discrepancies would likely be investigated, but a specific multi-reader adjudication process for ground truth establishment is not described.

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

• No, an MRMC comparative effectiveness study involving human readers and AI assistance was not performed. This device is an automated microbiology system, not an AI-assisted diagnostic tool that augments human interpretation. Its performance is compared to a reference laboratory method rather than human readers.

5. Standalone Performance (Algorithm Only)

• Yes, the study evaluated the standalone performance of the BD Phoenix™ Automated Microbiology System. The device itself is an "algorithm only" system in the context of interpreting bacterial growth and determining MIC values. The reported EA and CA percentages directly reflect the algorithm's performance compared to the reference method.

6. Type of Ground Truth Used

• The ground truth used was the CLSI reference broth microdilution method (AST panels prepared according to NCCLS M7). For challenge isolates, results were compared to "expected results," which would also be derived from established microbiological standards.

7. Sample Size for Training Set

• The document does not provide specific details regarding a training set sample size. This summary focuses on the validation of the system, not the development or training of its internal algorithms.

8. How Ground Truth for Training Set was Established

• The document does not provide information on how ground truth was established for any potential training set. As a commercial system, the development process and initial training data details are typically proprietary and not part of the 510(k) public summary. The focus of the 510(k) is the validation of the final product.

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