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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-negative aerobic and facultative anaerobic bacteria isolates from pure culture for Enterobacterales and Non-Enterobacterales and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus, Enterococcus, and Streptococcus.

This premarket notification is for the BD Phoenix Automated Microbiology System with Imipenem-relebactam at a concentration of 0.0625/4-16/4 µg/mL. Testing is indicated for Acinetobacter calcoaceticus-baumannii complex, Enterobacterales, and Pseudomonas aeruginosa, as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC).

The BD Phoenix Automated Microbiology System - GN Imipenem-relebactam (0.0625/4 - 16/4 µg/mL) has demonstrated acceptable performance with the following organisms:

• Acinetobacter calcoaceticus-baumannii complex
• Enterobacterales (Citrobacter amalonaticus, Citrobacter braakii, Citrobacter farmeri, Citrobacter freundii, Citrobacter koseri, Citrobacter youngae, Enterobacter cloacae, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia marcescens)
• Pseudomonas aeruginosa

The Phoenix AST method is a broth-based microdilution test. The Phoenix panel is a sealed and self-inoculating molded polystyrene tray with 136 micro-wells containing dried reagents. The ID/AST combination panel includes an ID side (51 wells) with dried substrates for bacterial identification and an AST side (85 wells). The AST panel contains a wide range of two-fold doubling dilution concentrations of antimicrobial agents and growth and fluorescent controls at appropriate well locations. The AST panel does not include wells for isolate identification.

The Phoenix System utilizes a redox indicator for the detection of organism growth in the presence of an antimicrobial agent. The organism to be tested must be a pure culture and be preliminarily identified as Gram-positive or Gram-negative. Colonies are then suspended in ID broth and equated to a 0.5 McFarland suspension using a nephelometer device. A further dilution is made into AST broth (a cation-adjusted formulation of Mueller-Hinton broth containing 0.010% Tween 80), to which the redox-buffered oxidation-reduction AST indicator solution is added producing a blue color in the wells. The concentration of organisms in the final AST broth suspension is approximately 5 X 10^5 CFU/mL.

The Phoenix AST Broth is poured into the inoculation port of the AST panel and the inoculum flows into the panel, filling panel wells. Polyethylene caps are applied to seal the inoculation ports. An air admittance port is located in the panel lid to ensure adequate oxygen tension in the panel for the duration of the test. Inoculated panels are barcode scanned and loaded into the BD Phoenix Automated Microbiology System instrument where panels are continuously incubated at 35 °C ± 1 °C.

Continuous measurements of changes to the indicator as well as bacterial turbidity are used in the determination of bacterial growth. The instrument takes readings every 20 minutes. Organisms growing in the presence of a given antimicrobial agent reduce the indicator (changing it to a pink color). This signals organism growth and resistance to that antimicrobial agent. Organisms killed or inhibited by the antimicrobial agent do not cause reduction of the indicator and therefore do not produce a color change. The Phoenix instrument reads and records the results of the antimicrobial tests contained in the panel and interprets the reactions (based on the organism identification) to give a minimal inhibitory concentration (MIC) value and category interpretations (susceptible, intermediate, resistant, or not susceptible). AST results are available within 16 hours. This is an auto read result; no manual readings are possible with this system.

Additional comments concerning specific organism/antimicrobial combinations are provided from the software-driven expert system (BDXpert), using rules derived from CLSI documentation and/or the FDA-approved drug labeling.

The provided FDA 510(k) clearance letter describes the acceptance criteria and the study that proves the BD Phoenix™ Automated Microbiology System - GN Imipenem-relebactam (0.0625/4 - 16/4 µg/mL) device meets those criteria for Antimicrobial Susceptibility Testing (AST).

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The core acceptance criteria for AST devices are related to Essential Agreement (EA) and Category Agreement (CA) with a reference method. The study aims to demonstrate that the device's performance is substantially equivalent to the established reference method.

Note: The document mentions "The performance of the BD Phoenix Imipenem-relebactam met the combined acceptance criteria for all tested organisms, with overall EA and CA rates greater than 90%." This implicitly sets the 90% for EA and CA as the acceptance threshold.

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

• Clinical Isolates (Test Set):

  • Total: 1,111 isolates (862 fresh, 249 stock)
  • Organisms:
    • Acinetobacter baumannii/calcoaceticus complex (83 isolates)
    • Citrobacter freundii (21 isolates)
    • Citrobacter species (9 isolates)
    • Citrobacter koseri (26 isolates)
    • Enterobacter cloacae (60 isolates)
    • Escherichia coli (359 isolates)
    • Klebsiella aerogenes (58 isolates)
    • Klebsiella oxytoca (47 isolates)
    • Klebsiella pneumoniae (198 isolates)
    • Pseudomonas aeruginosa (176 isolates)
    • Serratia marcescens (74 isolates)
  • Provenance: Conducted at three U.S. clinical sites. Data consists of fresh and stock isolates, implying a mix of retrospective (stock) and prospective (fresh) collection.

• Challenge Isolates (Test Set):

  • Total: 85 isolates (these are specific strains with known resistance mechanisms)
  • Organisms:
    • Acinetobacter baumannii (7 isolates)
    • Citrobacter freundii (2 isolates)
    • Citrobacter koseri (2 isolates)
    • Enterobacter cloacae (12 isolates)
    • Escherichia coli (19 isolates)
    • Klebsiella aerogenes (4 isolates)
    • Klebsiella pneumoniae (24 isolates)
    • Pseudomonas aeruginosa (15 isolates)
  • Provenance: Tested at "each study site" (implying the same three U.S. clinical sites as for clinical isolates). These are typically retrospective isolates chosen to challenge the system.

• Reproducibility Isolates:

  • Total: 15 on-scale isolates (tested in triplicate over three days at three sites, for 405 data points).
  • Organisms: Enterobacter cloacae (2), Escherichia coli (5), Klebsiella aerogenes (1), Klebsiella pneumoniae (3) and Pseudomonas aeruginosa (4).
  • Provenance: Conducted at three clinical sites (for manual method) and three internal BD sites (for Phoenix AP instrument).

3. Number of Experts Used to Establish Ground Truth and Qualifications

This type of medical device (automated microbiology system for AST) does not typically involve human experts to establish "ground truth" in the same way an imaging AI might.

• Ground Truth Establishment: The ground truth for antimicrobial susceptibility testing is established by a reference method, specifically the CLSI frozen broth microdilution reference panel, prepared according to CLSI M07 guidelines. This is a standardized, laboratory-based method, not dependent on expert visual interpretation.
• No "experts" in the human-reader sense are described as establishing ground truth for the test set. The expertise lies in adherence to CLSI standards and methodologies.

4. Adjudication Method for the Test Set

• No human adjudication method (e.g., 2+1, 3+1) is mentioned or applicable for this type of device.
• The comparison is directly between the result from the BD Phoenix system and the CLSI frozen broth microdilution reference panel. Discrepancies are categorized as minor, major, or very major based on established AST definitions (Essential Agreement and Category Agreement).

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

• No, an MRMC study was NOT done. This type of study is relevant for diagnostic imaging interpretation devices where human reader performance is a key metric. For an automated microbiology system, the comparison is to a "gold standard" laboratory method (CLSI microdilution), not to human interpretation or human improvement with AI assistance.

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

• Yes, this is essentially a standalone (algorithm only) performance study. The BD Phoenix system is an automated device that reads and interprets the results without human subjective input in the interpretative step. The "human-in-the-loop" aspects are limited to initial inoculum preparation (though automated options are also available and validated) and loading the panel, not interpreting the results. The comparison is the device's output (MIC and category) against the reference method.

7. The Type of Ground Truth Used

• The ground truth used is the CLSI frozen broth microdilution reference panel, which serves as the gold standard reference method for antimicrobial susceptibility testing.

8. The Sample Size for the Training Set

• The document does not explicitly state a separate "training set" sample size. For this type of automated system, which uses a growth-based detection principle rather than a machine learning model trained on large datasets of examples, the concept of a distinct "training set" in the modern AI sense is typically not applicable.
• The system's "training" or development would involve extensive internal R&D, algorithm refinement, and validation using proprietary data over time, which precedes a 510(k) submission. The data provided in the 510(k) is for the validation/test set to demonstrate performance.

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

• As a conventional, growth-based automated system rather than a machine learning device, there isn't a "training set" with ground truth established in the sense of human labeling or annotation.
• The system operates based on predefined biochemical reactions and growth kinetics, and its algorithms are built upon established microbiological principles and CLSI guidelines. Any internal development and testing would likewise use CLSI reference methods to establish expected outcomes for algorithm development and calibration.

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The BD Phoenix Automated Microbiology System is intended for the in vitro rapid identification (ID) and the quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram-positive bacteria from pure culture belonging to the genera Staphylococcus, other gram positive cocci and gram positive bacilli and of most Gram-negative aerobic and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and Non-Enterobacteriaceae.

BD Phoenix is an automated system for the rapid identification (ID) and antimicrobial susceptibility testing (AST) of clinically relevant bacterial isolates. The BD Phoenix System utilizes a redox indicator to detect 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 Phoenix instrument reads and records of the antimicrobial tests contained in the panel and interprets the reactions (based on the organism identification) to give a minimal inhibitory concentration (MIC) value and category interpretations (susceptible, intermediate, resistant, or not susceptible).

The BDXpert™ System is a rule-based software tool that provides expert advice based on organism ID and AST results obtained by broth micro-dilution on the BD Phoenix Instruments. BDXpert rule development is based on published information available through standards organizations, current scientific literature, and FDA's STIC; custom rules may be user defined if desired. The BDXpert System rule logic is applied to the susceptible, intermediate, and resistant (SIR) result, which is based on the breakpoint table and interpretation rule set included either in the BDXpert System on the standalone Phoenix instruments or through the BDXpert System on the connected BD EpiCenter™ data management system (EpiCenter) or BD Synapsys™ Informatics Solution (Synapsys). The resulting instrument report contains information such as: MIC interpretation, BDXpert rules, special messaging, resistance markers, etc. The expert results can then be sent to the Laboratory Information System (LIS).

Synapsys is a browser-based software platform operating in the clinical lab setting, offering secure connectivity and data storage, integrated workflows, and analytics tools. Synapsys consists of software servers operating the application and database, securely networked through a facility IT infrastructure to diagnostic instrumentation, external healthcare IT systems such as the LIS, and browser-enabled client devices for operating the system. Synapsys connects BD lab automation and diagnostic instruments to a common database and provides a single user interface to integrate laboratory workflows. Synapsys provides bi-directional communication with BD Phoenix and is able to process ID and AST results received from a BD Phoenix instrument. The system will automatically associate a known organism ID result, regardless of source, to any ID/AST or AST only Phoenix panel(s) that have the same accession/isolate number and lack an organism ID.

While the provided text describes an FDA 510(k) premarket notification for the BD Phoenix™ Automated Microbiology System, it does not contain the detailed information necessary to answer your specific questions regarding acceptance criteria and the study that proves the device meets them.

The document primarily focuses on:

• Regulatory clearance: The FDA's determination of substantial equivalence to a predicate device.
• Device description: How the BD Phoenix system works for identification (ID) and antimicrobial susceptibility testing (AST).
• Comparison to predicate: Highlighting similarities and differences, particularly in data management connectivity (Synapsys vs. EpiCenter).
• General compliance: Mentioning adherence to standards like ISO 13485, IEC 62304, and ISO 14971, and FDA guidance on software functions.

Missing Information:

The document explicitly states under "V. Performance Characteristics (if/when applicable)": "Performance testing was conducted to verify compliance with specified design requirements... Software verification and validation activities demonstrate that BD Phoenix Instrument connected to Synapsys will perform as intended when used in accordance with device labeling." However, it does not provide the results of these performance tests, nor does it detail the specific acceptance criteria or the methodology of the study that generated those results.

Therefore, I cannot populate the table or answer the specific questions about the study design, sample sizes, ground truth establishment, or expert involvement based solely on the provided text. This type of detailed performance data is typically found in the full 510(k) submission, which is more extensive than this summary letter.

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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-negative and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus, and Streptococcus, This premarket notification is for the BD Phoenix™ Automated Microbiology System with Ciprofloxacin at a concentration of 0.0156-4 ug/mL. Ciprofloxacin 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.

This submission is for a range extension of a single antimicrobial cleared for use on BD Phoenix ID/AST or AST only panels. The ID portion of the ID/AST combination panel was not subject to review in this submission.

The Phoenix AST method is a broth-based microdilution test. The Phoenix panel is a sealed and self-inoculating molded polystyrene tray with 136 micro-wells containing dried reagents. The ID/AST combination panel includes an ID side (51 wells) with dried substrates for bacterial identification and an AST side (85 wells). The AST panel contains a wide range of two-fold doubling dilution concentrations of antimicrobial agents and growth and fluorescent controls at appropriate well locations. The AST panel does not include wells for isolate identification.

The Phoenix System utilizes a redox indicator for the detection of organism growth in the presence of an antimicrobial agent. The organism to be tested must be a pure culture and be preliminarily identified as Gram-positive or Gram-negative. Colonies are then suspended in ID broth and equated to a 0.5 McFarland suspension using a nephelometer device. A further dilution is made into AST broth (a cation-adjusted formulation of Mueller-Hinton broth containing 0.010% Tween 80), to which the redox-buffered oxidation-reduction AST indicator solution is added producing a blue color in the wells. The concentration of organisms in the final AST broth suspension is approximately 5 X 105 CFU/mL.

The Phoenix AST Broth is poured into the inoculation port of the AST panel and the inoculum flows into the panel, filling panel wells. Polyethylene caps are applied to seal the inoculation ports. An air admittance port is located in the panel lid to ensure adequate oxygen tension in the panel for the duration of the test. Inoculated panels are barcode scanned and loaded into the BD Phoenix Automated Microbiology System instrument where panels are continuously incubated at 35 ℃ ± 1 ℃.

Continuous measurements of changes to the indicator as well as bacterial turbidity are used in the determination of bacterial growth. The instrument takes readings every 20 minutes. Organisms growing in the presence of a given antimicrobial agent reduce the indicator (changing it to a pink color). This signals organism growth and resistance to that antimicrobial agent. Organisms killed or inhibited by the antimicrobial agent do not cause reduction of the indicator and therefore do not produce a color change. The Phoenix instrument reads and records the results of the antimicrobial tests contained in the panel and interprets the reactions (based on the organism identification) to give a minimal inhibitory concentration (MIC) value and category interpretations (susceptible, intermediate, resistant, or not susceptible). AST results are available within 16 hours. This is an auto read result; no manual readings are possible with this system.

Additional comments concerning specific organism/antimicrobial combinations are provided from the software-driven expert system (BDXpert), using rules derived from CLSI documentation and/or the FDA-approved drug labeling.

The BD Phoenix Automated Microbiology System - GN Ciprofloxacin (0.0156-4 ug/mL) is an antimicrobial susceptibility testing system. The provided text describes the performance characteristics of this device, particularly for Salmonella species, and the study conducted to demonstrate its performance against acceptance criteria.

1. Table of Acceptance Criteria and Reported Device Performance:

(Note: The document states "The BD Phoenix Ciprofloxacin performance met the acceptance criteria for Salmonella with overall EA and CA greater than 90%." The specific numerical acceptance criteria for Min, Maj, Vmj are usually found in the referenced guidance documents but are not explicitly detailed as numerical percentages in the provided text for the device itself, other than the observed performance.)

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

• Clinical Isolates: 47 (fresh: 7 (14.9%), stock: 40 (85.1%))
  • Organisms: Salmonella species (43 isolates), Salmonella enterica ssp. enterica serovar Typhi (4).
  • Provenance: "Clinical testing was conducted at three U.S. sites." (Suggests prospective and retrospective clinical data from U.S. sources).
• Challenge Isolates: 82 stock isolates
  • Organisms: Salmonella species (79), Salmonella enterica ssp. enterica serovar Typhi (3).
  • Provenance: "Additional stock challenge isolates were tested at each study site." (Implying laboratory-controlled challenge strains, likely geographically diverse or from culture collections, but no specific country of origin is mentioned beyond "U.S. sites" for the clinical part which also conducted challenge testing).
• Reproducibility Study Isolates: 14 isolates of non-fastidious Gram-negative organisms (including Pseudomonas aeruginosa (1), Salmonella enterica ssp. enterica serovar Paratyphi A (1), and Salmonella species (11)).

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

The ground truth was established using the CLSI frozen broth microdilution reference panel, prepared according to CLSI M07 guidelines. This is a standardized laboratory reference method, implicitly implying experts in microbiology and antimicrobial susceptibility testing were involved in its execution and interpretation, rather than individual "experts" reviewing each case for a ground truth panel. The document does not specify the number or qualifications of "experts" as individuals but relies on the standardized, recognized reference method.

4. Adjudication Method for the Test Set:

Not applicable in the typical sense of expert adjudication for diagnostic imaging or similar devices. The ground truth is determined by a universally accepted reference laboratory method (CLSI frozen broth microdilution). The comparison involves measuring agreement between the device and this reference method.

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

A multi-reader multi-case (MRMC) comparative effectiveness study was not conducted. The study focuses on the standalone performance of the automated system against a reference method, not on human reader performance with or without AI assistance.

6. Standalone (Algorithm Only) Performance:

Yes, a standalone performance study was conducted. The "BD Phoenix Automated Microbiology System" is an automated device, and its performance was evaluated against a reference method (CLSI frozen broth microdilution) without human intervention in the MIC determination or category interpretation on the device side. The reported Essential Agreement (EA) and Category Agreement (CA) metrics represent this standalone algorithmic performance.

7. Type of Ground Truth Used:

The ground truth used was expert consensus methodology/reference standard, specifically the CLSI frozen broth microdilution reference panel prepared according to CLSI M07 guidelines. This is the gold standard for antimicrobial susceptibility testing.

8. Sample Size for the Training Set:

The document does not explicitly state the sample size for a training set. This type of device (AST system) is typically developed and validated against extensive datasets during its initial creation and subsequent range extensions. However, the provided text describes the validation/test set used for this specific premarket notification (47 clinical isolates and 82 challenge isolates for Salmonella). This suggests a re-evaluation of performance based on updated breakpoints rather than a new algorithm development requiring a separate training set description in this 510(k) summary.

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

As no explicit training set sample size is provided, the method for establishing its ground truth is also not detailed. However, if a training phase was involved in the initial development of the BD Phoenix system, it would have traditionally relied on similar reference methodologies like CLSI broth microdilution to establish accurate MIC values and corresponding susceptibility categories.

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