(45 days)
The BD Phoenix™ Automated Microbiology System is intended for the rapid identification and in vitro antimicrobial susceptibility testing of isolates from pure culture of most aerobic and facultative anaerobic Gram-negative and Gram-positive bacteria of human origin.
The BD Phoenix™ Automated Microbiology System is intended for in vitro quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram-negative aerobic and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and Non-Enterobacteriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus and Enterococcus.
This premarket notification is for the addition of the antimicrobial agent ampicillin-sulbactam at concentrations of 2/1 - 32/16 ug/mL to Gram Positive ID/AST or AST only Phoenix panels. Ampicillin-sulbactam has been shown to be active 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:
Staphylococcus aureus (beta-lactamase producing)
Active In Vitro Against:
Staphylococcus aureus (beta-lactamase and non-beta-lactamase producing)
Staphylococcus epidermidis (beta-lactamase and non-beta-lactamase producing)
Staphylococcus saprophyticus (beta-lactamase and non-beta-lactamase producing)
Enterococccus faecalis (formally Streptococcus faecalis)
The BD Phoenix Automated Microbiology System (Phoenix System) is an automated system for the rapid identification (ID) and antimicrobial susceptibility testing (AST) of clinically relevant bacterial isolates. The system includes the following components:
- BD Phoenix instrument and software. .
- BD Phoenix panels containing biochemicals for organism ID testing and antimicrobial agents . or AST determinations.
- BD Phoenix ID Broth used for performing ID tests and preparing AST Broth inoculum. .
- BD Phoenix AST Broth used for performing AST tests only. .
- BD Phoenix AST Indicator solution added to the AST Broth to aid in bacterial growth . determination.
The Phoenix panel is a sealed and self-inoculating molded polystyrent tray with 136 micro-wells containing dried reagents. Organisms for succeptive solate. For each isolate, an inoculation premimatily nonthrou as a Sean dard is prepared in Phoenix ID broth.
The Phoenix AST method is a broth based microdilution test. The Phoenix System uilizes a redox indicator for the detection of organism growth in the presence of an antimicrobial agent. Measurements of the material to the material 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 55 ℃. THe instrument takes roading of unimum 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 for ampicillin-sulbactam, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implicitly defined by the benchmarks set by the NCCLS reference broth microdilution method and the FDA draft guidance. While specific numeric acceptance criteria are not explicitly stated as "must be greater than X%", the study aims to demonstrate "substantially equivalent performance" to the reference method and achieve high reproducibility.
The relevant performance metrics and the reported results for the BD Phoenix™ System with ampicillin-sulbactam in Gram-positive organisms are:
| Performance Metric | Acceptance Criteria (Implicit) | Reported Device Performance (Ampicillin-sulbactam, Gram-Positive) |
|---|---|---|
| Reproducibility | Intra-site reproducibility greater than 90% (for this antimicrobial agent) | Overall intra-site reproducibility > 90% |
| Inter-site reproducibility greater than 95% (for this antimicrobial agent) | Overall inter-site reproducibility > 95% | |
| 95% reproducibility or greater within ± 1 dilution (for this antimicrobial agent) | Demonstrated 95% reproducibility or greater within ± 1 dilution | |
| Accuracy (Essential Agreement - EA) | Substantially equivalent performance to NCCLS reference method. Typically, high agreement is expected (e.g., >90%). | 97.4% |
| Accuracy (Category Agreement - CA) | Substantially equivalent performance to NCCLS reference method. Typically, high agreement is expected (e.g., >90%). | 88.7% |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set: The "Clinical Studies" section notes that 1616 isolates (clinical, stock, and challenge) were used to calculate Essential Agreement (EA) and Category Agreement (CA) for ampicillin-sulbactam.
- Data Provenance:
- Clinical isolates: Tested across "multiple geographically diverse sites" within the United States. This implies prospective collection from various clinical settings.
- Stock and challenge isolates: Also tested, but their specific origin (e.g., specific culture collections or laboratory strains) is not detailed.
- Overall: Mixture of prospective (clinical) and possibly retrospective or banked (stock/challenge) isolates.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document states that the Phoenix System results were compared to the NCCLS reference broth microdilution method. This laboratory method itself serves as the "ground truth" or reference standard. It's a standardized laboratory technique, not based on expert interpretation like radiology images. Therefore, the concept of "number of experts" and their "qualifications" for establishing ground truth doesn't directly apply in the same way it would for imaging diagnostics. The ground truth is derived from the established and validated laboratory procedure.
4. Adjudication Method for the Test Set
Not applicable. The ground truth is established by a standardized laboratory method (NCCLS reference broth microdilution) which yields a definitive result (MIC and category interpretation) rather than requiring adjudication among 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
Not applicable. This device is an automated microbiology system that performs in vitro antimicrobial susceptibility testing. It does not involve human "readers" interpreting results that would then be enhanced or compared with AI assistance. The system provides a direct measurement and interpretation.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
Yes, this study is inherently a standalone performance evaluation. The BD Phoenix™ Automated Microbiology System is designed to provide automated identification and AST results. The comparison is between the automated system's output and the NCCLS reference method's output. While human technicians operate the system and prepare inoculations, the "performance" being evaluated is the algorithm's ability to accurately determine MICs and category interpretations without human interpretive intervention beyond standard laboratory procedures.
7. The Type of Ground Truth Used
The ground truth used is the NCCLS reference broth microdilution method. This is a well-established and standardized laboratory method for determining antimicrobial minimum inhibitory concentrations (MICs) and susceptibility categories.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" for the BD Phoenix™ System or the specific ampicillin-sulbactam agent. This type of device, an automated laboratory instrument, is typically developed and validated using a structured approach that may involve internal R&D data for algorithm development, but this "training set" information is not part of the regulatory submission summary provided. The submission focuses on the validation or test set performance against a reference standard.
9. How the Ground Truth for the Training Set Was Established
As no explicit "training set" is described in the provided summary, information on how its ground truth was established is not available. However, based on typical device development, any internal development or optimization would likely have also used comparison to standardized laboratory methods like the NCCLS broth microdilution method as the ground truth.
§ 866.1645 Fully automated short-term incubation cycle antimicrobial susceptibility system.
(a)
Identification. A fully automated short-term incubation cycle antimicrobial susceptibility system is a device that incorporates concentrations of antimicrobial agents into a system for the purpose of determining in vitro susceptibility of bacterial pathogens isolated from clinical specimens. Test results obtained from short-term (less than 16 hours) incubation are used to determine the antimicrobial agent of choice to treat bacterial diseases.(b)
Classification. Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA.”