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The BD Phoenix™ Automated Microbiology System is intended for in vitro quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram-positive bacterial isolates from pure culture belonging to the genera Staphylococcus and Enterococcus.

This premarket notification is for the addition of the antimicrobial agent Daptomycin at concentrations of 0.125-32 ug/mL to Gram Positive ID/AST or AST only Phoenix panels. Daptomycin 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:

Enterococcus faecalis (vancomycin-susceptible strains only) Staphylococcus aureus (including methicillin-resistant strains)

Active In Vitro Against:

Enterococcus faecalis (vancomycin-resistant strains) Enterococcus faecium (including vancomycin-resistant strains) Staphylococcus epidermidis (including methicillin-resistant strains) Staphylococcus haemolyticus

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 . 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 panel is a sealed and self-inoculating molded polystyrene tray with 136 micro-wells The Phoenix paller is a scaled and sell first and sen interacting must be a purch issues and containing dried reagents. Organisms for susceptime isolate. For each isolate. For each isolation premimarily idontified as a cistandard is prepared in Phoenix ID broth.

The Phoenix AST method is a broth based microdilution test. The Phoenix System uilizes a redox I he Phoenix AST memor is a broaism growth in the presence of an antimicrobial agent.
Indicator for the detection of organism growth in the presence of an the de indicator for the delection of organism growth in als prosectial turbidity are used in the determination Measurements of Changes to the marcator as were as ontains 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 I he unstrument 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 summary of the acceptance criteria and study details based on the provided text:

Acceptance Criteria and Device Performance

Study Details

2. Sample size used for the test set and the data provenance:

• Test Set Size:
  • Essential Agreement (EA): 1568 isolates
  • Categorical Agreement (CA): 1268 isolates (This discrepancy might indicate that not all isolates yielding EA also had a defined categorical interpretation that could be compared, or simply a reporting choice).
• Data Provenance: Clinical, stock, and challenge isolates were tested across multiple geographically diverse sites. This suggests a mix of "real-world" clinical samples and controlled laboratory strains, with a prospective element (testing performed for the study). The country of origin is not explicitly stated but implied to be the US given the FDA submission.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

The ground truth was established by the CLSI reference broth microdilution method. No human experts are explicitly mentioned as establishing the ground truth for the test set in the way a diagnostic imaging study would use radiologists. The CLSI method itself is the "expert" ground truth.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set:

Not applicable. The ground truth was established by the CLSI reference broth microdilution method, which is a standardized laboratory procedure, not a human consensus process.

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:

Not applicable. This device is an automated microbiology system for antimicrobial susceptibility testing, not an AI-assisted diagnostic imaging or human-read interpretation system. The comparison is between the automated system and a reference laboratory method.

6. If a standalone (i.e. algorithm only, without human-in-the-loop performance) was done:

Yes, the study was a standalone evaluation of the BD Phoenix™ System. Its performance (MIC values and categorical interpretations) was directly compared to the CLSI reference method. The device is described as "fully automated" and the study evaluates its performance as such.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

The ground truth used was the CLSI reference broth microdilution method. This is a well-established, standardized laboratory method recognized as the gold standard for antimicrobial susceptibility testing.

8. The sample size for the training set:

The document does not explicitly state a separate "training set" size. The development and validation of an automated microbiology system like the Phoenix System typically involve extensive internal testing and refinement before formal clinical studies for regulatory submission. The provided study focuses on the performance validation for regulatory submission, where the system is evaluated against a reference method using the described test set.

9. How the ground truth for the training set was established:

Not applicable, as a distinct training set with explicitly defined ground truth establishment methods is not detailed in this regulatory submission for the addition of a new antimicrobial agent to an existing device. For an algorithm-based device, the ground truth for training would typically be established using the same CLSI reference method or similar gold standard laboratory techniques on a large, diverse collection of bacterial isolates.

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