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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 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, Enterococcus and Streptococcus.

This premarket notification is for the addition of the Phoenix Inducible Macrolide Resistance (iMLSb) Test in Staphylococcus species to Gram-positive ID/AST or AST only Phoenix panels. The Phoenix Inducible Macrolide Resistance Test is used to detect inducible macrolide-lincosamide-streptogramin B resistance in Staphylococcus species.

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 polystyrenc 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. Phoenix panels are inoculated with a specified organism density and placed into the instrument.

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. Measurcments 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).

The provided text describes the BD Phoenix™ Automated Microbiology System for detecting inducible macrolide resistance (iMLSb) in Staphylococcus species. Here's a breakdown of the acceptance criteria and the study that proves the device meets them:

1. A table of acceptance criteria and the reported device performance

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Sample Size for Test Set:
  • Clinical Study Isolates: Not explicitly stated as a single number for the entire test set. However, for the Phoenix Inducible Macrolide Resistance Test, the reported "CA (n)" is 295, indicating 295 isolates were used for this specific test within the clinical study.
  • Site Reproducibility: A "panel of Gram-positive isolates" was used. Each site tested these isolates in triplicate on three different days. The exact number of isolates in this panel is not specified.
• Data Provenance: Clinical, stock, and challenge isolates were tested at multiple geographically diverse sites across the United States. The study type for clinical isolates was comparative against a reference method, which is typical for prospective data collection in such studies, though not explicitly stated. Challenge sets are typically retrospective (known results).

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

The document does not explicitly state the number of experts and their qualifications used to establish the ground truth for the test set. The ground truth for clinical isolates was established by comparing to the "CLSI reference broth microdilution method". For challenge isolates, results were compared to "expected results," implying a pre-defined ground truth. The interpretation of these reference methods would typically be performed by trained laboratory personnel, but no specific expert qualifications are provided.

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

The document does not describe any specific adjudication method (like 2+1 or 3+1) for resolving discrepancies in the test set. It mentions comparison to a reference method, suggesting that the reference method's result served as the definitive interpretation.

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, a multi-reader multi-case (MRMC) comparative effectiveness study was not done in the context of human readers with or without AI assistance. This device is an automated system (BD Phoenix Automated Microbiology System) for in vitro susceptibility testing, not an AI-assisted diagnostic tool that aids human interpretation of images or other data. 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, this was a standalone performance study. The BD Phoenix Automated Microbiology System is an "algorithm only" type of device in the sense that it automatically performs the susceptibility testing and provides results (MIC values and category interpretations S, I, R, or N) without direct human interpretation within the measurement process itself. The study evaluates the performance of this automated system against reference methods.

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

The primary type of ground truth used was:

• Reference Method Results: For clinical isolates, the "CLSI reference broth microdilution method" was used as the ground truth. This is a laboratory-based, standardized method considered the gold standard for antimicrobial susceptibility testing.
• Expected Results: For challenge isolates, "expected results" were used. This typically refers to isolates with well-characterized resistance profiles, often obtained from reference laboratories or collections.

8. The sample size for the training set

The document does not specify a separate "training set" for the BD Phoenix Automated Microbiology System in the context of this 510(k) submission. This is an antimicrobial susceptibility testing (AST) system; its "training" fundamentally involves the development and calibration of the instrument and its reagent panels to accurately detect bacterial growth and interpret MICs according to established microbiological principles and CLSI guidelines. The performance data presented (site reproducibility and clinical studies) is primarily for verification/validation.

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

Since a distinct "training set" as understood in machine learning (where ground truth is typically assigned by experts for algorithm learning) is not explicitly mentioned or applicable in the traditional sense for this type of automated microbiology system, the method for establishing ground truth for a training set is not described. The system's underlying design and calibration would have relied on extensive microbiological knowledge and reference methods, ensuring its programmed interpretations align with CLSI standards.

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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 by minimal inhibitory concentration (MIC) of most Gram-negative aerobic and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and Non-Enteriaceae 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 ertapenem at concentrations of 0.25-32 ug/mL to Gram-negative ID/AST or AST only Phoenix panels. Erapenem 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:
Escherichia coli
Klebsiella pneumoniae

Active In Vitro:
Citrobacter freundii
Citrobacter koseri
Enterobacter aerogenes
Enterobacter cloacae
Klebsiella oxytoca
Morganella morganii
Proteus mirabilis
Proteus vulgaris
Providencia rettgeri
Providencia stuartii
Serratia marcescens

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 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. Phoenix panels are inoculated with a specified organism density and placed into the instrument.

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).

Here's a breakdown of the acceptance criteria and study information based on the provided text, adapted as if it were for an AI device for clarity in a modern context.

1. Table of Acceptance Criteria and Reported Device Performance

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

• Test Set Sample Size: The document indicates that "Clinical, stock and challenge isolates were tested." However, specific numerical sample sizes for each type of isolate are not provided in the summary.
• Data Provenance: The data was collected from "multiple geographically diverse sites across the United States." The study used a combination of:
  • Clinical isolates: Presumably prospective as they represent real-world samples.
  • Stock isolates: Likely retrospective or pre-existing lab strains.
  • Challenge isolates: Likely retrospective or pre-existing, used for specific performance verification against known results.

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

The document does not mention the use of experts to establish ground truth for the test set. Instead, the ground truth was established by:

• CLSI reference broth microdilution method: This is a standardized, established laboratory method, not reliant on individual expert interpretation for each case.
• Expected results for Challenge set isolates: These "expected results" would be pre-determined values for known strains, which could have been established by consensus or by previous rigorous testing using reference methods.

4. Adjudication Method for the Test Set

No explicit adjudication method (e.g., 2+1, 3+1) is described for the test set. The comparison was made directly against the CLSI reference broth microdilution method or expected results for challenge isolates, which serve as the definitive standard.

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

• No, an MRMC comparative effectiveness study was not done. This study evaluates the performance of an automated microbiology system (BD Phoenix™) against a reference standard (CLSI broth microdilution method) for antimicrobial susceptibility testing. It does not involve human readers or assess the improvement of human readers with AI assistance.

6. Standalone (Algorithm Only) Performance Study

• Yes, a standalone performance study was done. The entire study is a standalone evaluation of the BD Phoenix™ Automated Microbiology System (which incorporates an algorithm to interpret results) by comparing its outputs (MIC values and category interpretations) against the CLSI reference method. There is no human-in-the-loop component described in the performance evaluation.

7. Type of Ground Truth Used

The primary ground truth used was the CLSI reference broth microdilution method (AST panels prepared according to NCCLS M7). For challenge isolates, "expected results" were used.

8. Sample Size for the Training Set

The document does not provide information on the sample size used for the training set for the BD Phoenix™ system's underlying algorithms. This is typical for such submissions, as the focus is on the performance of the final, already-developed device.

9. How the 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. Similar to the training set sample size, this information is not typically included in the summary for a 510(k) submission for a device like this, which is an automated system rather than a de novo AI model with publicly disclosed training data. It's assumed the system was developed and validated internally using appropriate microbiological standards.

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