Search Results

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.

Ask a specific question about this device