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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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The BD Phoenix™ Automated Microbiology System is intended for the in vitro rapid identification (ID) and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram negative aerobic and facultative anaerobic bacteria belonging to the family Enterobacteriaceae and non-Enterobacteriaceae.

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. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD PhoenixTM AP System.
  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 ℃ ± 1 °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 performance study for the BD Phoenix Automated Microbiology System - GN Ceftaroline (0.0156-4 ug/mL). This system is designed for the rapid identification and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of Gram-negative bacteria.

Here's an analysis of the acceptance criteria and the study that proves the device meets them:

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

The document implicitly refers to performance criteria for Essential Agreement (EA) and Category Agreement (CA) as set forth in the FDA guidance document, "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems." While specific numerical acceptance criteria (e.g., "must achieve >90% EA") are not explicitly stated as "acceptance criteria" directly in the provided text, the reported performance is compared against the CLSI reference method to demonstrate substantial equivalence. For AST systems, typical FDA expectations are generally high agreement rates.

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

• Test Set Sample Size: The number of isolates tested for Essential Agreement (EA) and Category Agreement (CA) was 987 (n=987) for clinical and challenge isolates combined.
• Data Provenance: The data was collected from multiple geographically diverse sites across the United States. The study included clinical, stock, and challenge isolates. This indicates a combination of real-world clinical samples, laboratory-maintained stock cultures, and specific challenge strains designed to test the limits of the system. The study appears to be prospective in nature, as it describes actively testing isolates to demonstrate performance.

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

The document does not specify the number of experts or their qualifications for establishing the ground truth. It states that Phoenix System results for clinical isolates were compared to the results obtained from the CLSI reference broth microdilution method. This method itself serves as the gold standard, and the interpretation would typically follow CLSI guidelines by trained laboratory personnel, but no specific "experts" for ground truth establishment are detailed here.

4. Adjudication method for the test set:

The document does not describe an adjudication method for discrepancies. The device's results are directly compared to the CLSI reference broth microdilution method. Deviations form the basis of the EA and CA calculations.

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:

This is not an MRMC comparative effectiveness study. The device is an automated system for antimicrobial susceptibility testing, not an AI-assisted diagnostic tool for human readers. Therefore, the concept of improving human reader performance with AI assistance is not applicable here. The device itself performs the interpretation.

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

Yes, a standalone performance study was done. The entire evaluation focuses on the performance of the "BD Phoenix™ Automated Microbiology System" itself (which includes the instrument, software, and panels) in determining antimicrobial susceptibility. The results (MIC values and category interpretations S, I, R, or N) are generated directly by the system based on its automated readings and algorithms. This is an "algorithm only" performance, as the system provides the final interpretive results without requiring human interpretation of raw data beyond initial organism setup.

7. The type of ground truth used:

The ground truth used for performance comparison was the CLSI reference broth microdilution method results. For challenge isolates, results were compared to "expected results," which would also be derived from a validated reference method or known characteristics of the challenge strains.

8. The sample size for the training set:

The document does not explicitly state the sample size for the training set. This document describes the "performance studies" for the pre-developed device, not the development or training of the underlying algorithms. Automated Microbiology Systems are typically developed and validated using extensive in-house datasets, but those details are not usually part of a 510(k) summary focused on post-development performance evaluation.

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. As mentioned above, this document focuses on the performance evaluation of the final device for regulatory submission, not its developmental history or the specifics of how its internal algorithms were initially trained and validated. It can be inferred that the training would also have involved comparison to established reference methods like CLSI broth microdilution, but no details are given.

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The BD Phoenix Automated Microbiology System is intended for the in vitro rapid identification (ID) and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of Gram Negative aerobic and facultative anaerobic bacteria belonging to the family Enterobacteriaceae and non-Enterobacteriaceae.

BD Phoenix CPO detect is a qualitative confirmatory test that uses a growth-based algorithm intended to phenotypically detect carbapenemase-production in Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii on Gram-negative ID/AST or AST only Phoenix panels. The test also provides the Ambler classification (Class B and Class D) of the carbapenemase produced. One of three test configurations are available per panel for carbapenemase detection with/without Ambler classification for the target organism groups. BD Phoenix CPO detect does not report multiple classes of carbapenemases from a single isolate.

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. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD Phoenix™ AP System.

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° ± 1°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 document describes the acceptance criteria and the study that proves the device, BD Phoenix™ CPO detect - GN, meets these criteria.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" as a separate, defined list of numerical targets before presenting performance. However, typical acceptance criteria for such devices focus on high sensitivity (Positive Percent Agreement - PPA) and specificity (Negative Percent Agreement - NPA) for detection, and accuracy for classification. The reported performance is summarized below from the "Performance of BD Phoenix™ Automated Microbiology System for Gram-negative Organisms" and "BD Phoenix™ CPO detect: Carbapenemase Classification" tables.

Acceptance Criteria (Implied by Performance Expectations for Medical Devices) and Reported Device Performance:

Note: The "Unclassified isolates in either the Phoenix or reference system are not included in these calculations" represents a more ideal or 'clean' performance, while "All isolates are included in these performance calculations" provides a more comprehensive view, including instances where the device could not provide a classification or provided an incorrect one.

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

• Test Set Sample Size:
  • Detection of carbapenemase: 1452 isolates (Total)
  • Carbapenemase Classification (9-Well Configuration):
    • N=1357 (when unclassified isolates are excluded)
    • N=1452 (when all isolates are included)
  • Carbapenemase Classification (6-Well Configuration):
    • N=1039 (when unclassified isolates are excluded)
    • N=1099 (when all isolates are included)
• Data Provenance: The study used "Clinical fresh and stock isolates" tested across "multiple sites" and "Challenge isolates obtained from domestic and international sources." This indicates a mix of prospective (fresh clinical isolates) and retrospective (stock isolates, challenge isolates) data, collected from various geographical locations (domestic and international).

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

The document does not specify the number of experts or their qualifications for establishing the ground truth. It refers to a "composite reference method" and "Phenotypic testing" and "Genotypic testing," which suggests laboratory-based methods rather than human expert reads of images, as might be typical for AI in imaging.

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

Not applicable in the context described. The ground truth was established by laboratory methods (phenotypic and genotypic testing), not by multiple human readers requiring adjudication.

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, an MRMC comparative effectiveness study was not done. This device is an automated microbiology system for detecting carbapenemase production and classification, not an AI for assisting human readers in interpreting medical images. Therefore, the concept of human readers improving with AI assistance does not apply here.

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

Yes, the study describes the standalone performance of the BD Phoenix™ CPO detect system. The performance metrics (PPA, NPA) are presented for the device against the established ground truth, indicating its ability to detect and classify carbapenemase production without direct human intervention in the interpretation of the results from the system itself.

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

The ground truth was a composite reference method combining:

• Phenotypic testing: CLSI-recommended modified Carbapenem Inactivation Method (mCIM) assay and carbapenem MIC results.
• Genotypic testing: Multiplex PCR for detection of genes to assign Ambler classification (Class A, B, D).

8. The sample size for the training set

The document does not specify the sample size for a training set. Given that this is a "growth-based algorithm" for an automated microbiology system and not necessarily a machine learning model trained on a large dataset of prior test results or images, the concept of a distinct 'training set' for an AI algorithm might not apply in the conventional sense of deep learning. The system's "algorithm" is likely based on established microbiological principles and a decision tree derived from growth patterns and biochemical reactions rather than iterative training on labeled data in the way modern AI models are.

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

As the concept of a distinct 'training set' for an AI algorithm is not explicitly detailed or conventionally applied here for this type of device, the method for establishing ground truth for a training set is not described in the document. The description focuses on the validation of the device's performance against reference methods.

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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.

Meropenem-vaborbactam 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 Enterobacter cloacae species complex Escherichia coli Klebsiella pneumoniae

Active In Vitro but clinical significance is unknown Citrobacter freundii Citrobacter koseri Enterobacter aerogenes Klebsiella oxytoca Morganella morganii Proteus mirabilis Providencia spp. 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. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD Phoenix™ AP System.

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° ± 1°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).

1. Acceptance Criteria and Reported Device Performance

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

• Test Set Sample Size for Clinical and Challenge Isolates: 1141 isolates.
• Data Provenance: The study used a combination of clinical, stock, and challenge isolates. These were tested across multiple geographically diverse sites across the United States. This indicates a prospective and multi-site approach for clinical data collection, supplemented with controlled "stock" and "challenge" isolates. Specific details on the breakdown of clinical vs. stock/challenge isolates are not provided, nor is the exact number of contributing sites.

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

The document does not specify the number of experts used or their qualifications for establishing ground truth. However, the ground truth for clinical isolates was established by the CLSI reference broth microdilution method. This is a standardized laboratory method, and its execution would typically involve trained laboratory personnel rather than a subjective expert consensus in the way a radiologist reads an image. For "expected results" for challenge isolates, this typically refers to pre-determined, known susceptibility profiles.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method in the traditional sense of multiple expert readers. The comparison is made against the CLSI reference broth microdilution method for clinical isolates and "expected results" for challenge isolates. These are objective, laboratory-based methods, removing the need for a subjective adjudication process by human experts.

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. The device is an automated microbiology system that performs antimicrobial susceptibility testing (AST) and does not involve human readers in the interpretation of results in the way an AI for image analysis would. Therefore, the concept of human readers improving with or without AI assistance is not applicable to this device.

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

Yes, a standalone performance study was done. The BD Phoenix Automated Microbiology System is an automated system providing quantitative determination of antimicrobial susceptibility. Its performance (Essential Agreement and Category Agreement) was directly compared to the CLSI reference broth microdilution method, which represents its standalone performance without human interpretation of the primary data generated by the system.

7. The Type of Ground Truth Used

• Clinical Isolates: The ground truth was established using the CLSI reference broth microdilution method (AST panels prepared according to CLSI M7). This is a gold standard laboratory method for antimicrobial susceptibility testing.
• Challenge Isolates: The ground truth was based on "expected results," implying pre-defined or known susceptibility profiles for these controlled isolates.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" or its sample size. This type of device is an automated laboratory instrument, and its performance is typically evaluated against reference methods rather than through a machine learning training paradigm with separate training and test sets as seen in AI imaging devices. The "training" in this context would likely refer to the initial development and calibration of the system by the manufacturer using internal data, which is not detailed in this regulatory summary.

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

Since a "training set" is not explicitly discussed as per the typical AI/ML development cycle, there is no information on how its ground truth was established within this document. The focus of the 510(k) submission is on the comparison of the device's performance against established reference methods (CLSI broth microdilution) for the purpose of demonstrating substantial equivalence.

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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 Enterobacteriaceae and Non-Enteriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus, Enterococcus and Streptococcus.

Ceftolozane/tazobactam 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: Gram-negative bacteria Enterobacter cloacae Escherichia coli Klebsiella oxytoca Klebsiella pneumoniae Proteus mirabilis Pseudomonas aeruginosa

Active In Vitro but clinical significance is unknown: Gram-negative bacteria Citrobacter koseri Morganella morganii Proteus vulgaris Providencia stuartii Serratia liquefaciens 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. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD PhoenixTM AP System.

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 ℃ ± 1 °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).

1. Acceptance Criteria and Reported Device Performance

Note on Vmj Error: While a significant initial Vmj error rate was noted for E. coli, the submission indicates that additional testing and replicate analysis demonstrated no Vmj errors, suggesting the device ultimately met an acceptable standard for this metric.

2. Sample Size and Data Provenance (Test Set)

• Sample Size:
  • Clinical and Challenge Isolates: 1179 isolates in total ("All Organisms" in the performance table).
    • Specifically, 1034 Enterobacteriaceae isolates.
    • Specifically, 145 Pseudomonas aeruginosa isolates.
    • An "additional comparative study" included 66 resistant E. coli isolates to further investigate very major errors.
  • Reproducibility Test: A "panel of Gram-negative isolates" was used, tested in triplicate on three different days. The exact number of isolates is not specified.
• Data Provenance: The isolates were tested "across multiple geographically diverse sites across the United States." Whether the data was purely retrospective or involved prospective collection is not explicitly stated, but "clinical, stock and challenge isolates" suggests a mix, possibly including isolates collected for the purpose of the study (prospective) and pre-existing isolates (retrospective/stock).

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

The document does not explicitly state the number or qualifications of experts used to establish the ground truth for the test set.

4. Adjudication Method (Test Set)

The document does not explicitly describe an adjudication method for the test set. The "ground truth" was established by comparing the device's results to the CLSI reference broth microdilution method or to "expected results" for challenge isolates. This implies a direct comparison rather than a human expert adjudication process for the final MIC values.

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

No. The study described is a standalone performance evaluation of an automated antimicrobial susceptibility testing (AST) system compared to a reference method, not a comparative effectiveness study involving human readers with and without AI assistance. Therefore, there is no effect size reported for human readers' improvement with AI.

6. Standalone Performance Study

Yes. The study described is a standalone performance study. The "BD Phoenix™ Automated Microbiology System" (the algorithm/device) was directly compared to the CLSI reference broth microdilution method, which served as the gold standard for establishing ground truth for antimicrobial susceptibility.

7. Type of Ground Truth Used (Test Set)

The primary type of ground truth used was:

• Reference Method Comparison: For clinical isolates, the BD Phoenix System results were compared to the results obtained from the CLSI reference broth microdilution method (AST panels prepared according to CLSI M07). This is a recognized laboratory standard.
• Expected Results: For challenge isolates, the BD Phoenix System results were compared to "expected results." These expected results are typically derived from extensive prior characterization of these specific isolates, often using reference methods or phenotypic/genotypic analysis.

8. Sample Size for the Training Set

The document does not provide information on the sample size for a training set. This is typical for an AST device evaluation, where the "training" (if it occurs) is usually part of the initial development and validation of the instrument's growth detection and MIC interpretation algorithms, and not explicitly detailed in a 510(k) submission focused on the performance of a new antimicrobial agent on an existing system. The collected data represents the test set for evaluating the performance of the system with the new drug.

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

As no training set is explicitly mentioned or detailed, the method for establishing its ground truth is not provided. The entire submission focuses on the performance of the device against a defined test set where the CLSI reference method served as the ground truth.

Ask a specific question about this device

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, Enterococcus and Streptococcus.

Ceftazidime/avibactam 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 Citrobacter freundii complex Citrobacter koseri Escherichia coli Enterobacter aerogenes Enterobacter cloacae Klebsiella pneumoniae Klebsiella oxytoca Proteus spp. Pseudomonas aeruginosa

Active In Vitro but clinical significance is unknown Morganella morganii 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. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD Phoenix™ AP System.

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° ± 1°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 an analysis of the provided text regarding the acceptance criteria and the study proving the device meets them:

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

The document references the FDA guidance document, "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA", August 28, 2009 for the acceptance criteria. While the specific numerical thresholds for Essential Agreement (EA) and Category Agreement (CA) from this guidance aren't explicitly stated in the provided text, the reported performance is presented. Typically, for AST devices, acceptance criteria are set for these metrics.

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

• Sample Size for Test Set: 1348 isolates (This is the 'n' value reported for EA and CA).
• Data Provenance:
  • Clinical Studies: The study used "Clinical, stock and challenge isolates".
  • Geographic Origin: Tested "across multiple geographically diverse sites across the United States."
  • Retrospective or Prospective: Not explicitly stated, but the nature of a clinical study comparing to a reference method often involves prospective collection and testing or retrospective testing of collected isolates from clinical settings. The term "Clinical isolates were compared to the results obtained from the CLSI reference broth microdilution method" suggests these were real-world samples. "Challenge isolates" often refers to a pre-defined set of strains used to test specific performance aspects.

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

This information is not explicitly provided in the text. The ground truth for clinical isolates was established by the "CLSI reference broth microdilution method." While this is a standardized laboratory method, the number and qualifications of individuals performing these reference tests (who could be considered experts in applying the reference method) are not detailed.

4. Adjudication method for the test set

This information is not explicitly provided. The comparison is between the BD Phoenix System results and the CLSI reference broth microdilution method results. It's implied that discrepancies were evaluated to determine EA and CA, but a formal adjudication process (e.g., 2+1, 3+1 expert review in case of disagreement between tests) is not described.

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

This is not an MRMC study. The device is an automated antimicrobial susceptibility testing (AST) system. It performs the test and provides results (MIC values and categorical interpretations) directly, without requiring human "readers" in the same way an imaging or diagnostic AI system would. Therefore, the concept of "human readers improving with AI vs without AI assistance" does not apply here. This is an automated system being compared to a reference standard.

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 Automated Microbiology System is an automated device designed to determine antimicrobial susceptibility without continuous human intervention in the result interpretation once the samples are loaded. The study assesses the performance of this automated system directly against a reference method.

7. The type of ground truth used

• Clinical Isolates: The ground truth for clinical isolates was established by the CLSI reference broth microdilution method. This is a laboratory-based, standardized, and widely accepted "gold standard" method for antimicrobial susceptibility testing.
• Challenge Isolates: The ground truth for challenge isolates was compared to "expected results." This implies a pre-defined, known susceptibility profile for these specific strains, likely determined by the CLSI reference method or other validated methods.

8. The sample size for the training set

The document does not explicitly state the sample size for a training set. The descriptions focus on the validation (test) set. Automated microbiology systems like the BD Phoenix are generally developed and validated extensively over time, but the specific "training set" used for this particular antimicrobial agent's incorporation is not detailed in this regulatory summary. The system itself is "predicated" on an earlier cleared device (VITEK®2), suggesting that the base technology has been "trained" over many years/studies.

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

As the document does not explicitly identify a "training set" for this specific clearance, it also does not describe how its ground truth was established. For the system as a whole, the ground truth would have been established through extensive comparisons to reference methods (like CLSI broth microdilution) during its initial development and subsequent updates.

Ask a specific question about this device

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.

Ertapenem 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 Proteus mirabilis

Active In Vitro

Citrobacter freundii Citrobacter koseri Enterobacter aerogenes Enterobacter cloacae Klebsiella oxytoca (excluding ESBL producing isolates) Morganella morganii 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. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD Phoenix™ AP System.

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° ± 1°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 information for the BD Phoenix Automated Microbiology System - Ertapenem, based on the provided text:

1. Table of Acceptance Criteria and the Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets within the document, but rather implied by the FDA guidance document and the performance metrics (Essential Agreement and Category Agreement). The study's results demonstrated high agreement with the reference method.

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

• Test Set Sample Size: The clinical studies tested a combined total for Essential Agreement (EA) and Category Agreement (CA) of 1469 isolates for Ertapenem. This number likely represents a combination of clinical, stock, and challenge isolates.
• Data Provenance: The isolates were tested across multiple geographically diverse sites across the United States. The study primarily involved retrospective and prospective collection of isolates. "Clinical, stock and challenge isolates were tested" suggests a mix, with clinical isolates often being prospective, and stock/challenge isolates being retrospective.

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

The document does not specify the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience"). However, the ground truth for the clinical isolates was established by the CLSI reference broth microdilution method, which is a standardized and widely accepted laboratory procedure requiring trained personnel. For challenge isolates, the "expected results" were used, which would have been predetermined through expert consensus or established laboratory methods.

4. Adjudication Method for the Test Set

The document does not explicitly state an adjudication method like 2+1 or 3+1. The comparison was directly between the BD Phoenix System results and the CLSI reference broth microdilution method (or "expected results" for challenge isolates). Discrepancies would typically be reviewed by laboratory personnel following established protocols, but a formal adjudication process involving multiple independent reviewers is not detailed.

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. This device is an automated microbiology system for antimicrobial susceptibility testing, which provides automated results – it does not involve human "readers" interpreting images or cases in the same way an AI diagnostic tool for radiology might. Therefore, the concept of improving human reader performance with AI assistance is not applicable here.

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

Yes, a standalone performance evaluation was done. The BD Phoenix Automated Microbiology System is an automated system that provides minimal inhibitory concentration (MIC) values and categorical interpretations (S, I, R) directly. The study evaluates the performance of this system (algorithm and hardware) in comparison to a reference method, without direct human intervention in the interpretation of the results to be compared.

7. The Type of Ground Truth Used

The ground truth used was:

• For clinical isolates: The CLSI reference broth microdilution method results. This is a recognized laboratory "gold standard" for antimicrobial susceptibility testing.
• For challenge isolates: Expected results. These are typically established and verified results for strains with known susceptibility patterns, often used to challenge the limits of a system.

8. The Sample Size for the Training Set

The document does not specify the sample size for a training set. As this is a 510(k) submission for a device using an established technology (broth microdilution with automated reading and interpretation), it's likely that extensive training data was not explicitly required for this specific submission. The system's underlying algorithms and interpretations are built on years of microbiological data and established breakpoints, rather than a novel machine learning model that requires a distinct, massive training set for this specific submission. The validation focuses on the performance of the Ertapenem panel on the existing Phoenix system.

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

Since a specific training set size is not mentioned as part of this submission, the method for establishing its ground truth is also not detailed. However, the fundamental principles and interpretation algorithms for the BD Phoenix system would have been developed and refined over time using a vast amount of microbiological data, with ground truth established through standard microbiological techniques, including comparison to reference methods like CLSI broth microdilution.

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