(79 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, Non-Enterobacteriaceae and most glucose nonfermenting gram-positive bacteria isolates from pure culture belonging for Staphylococcus and Enterococcus.
This premarket notification is for the antimicrobial Ofloxacin at concentrations of 0.25-8 µg to Gram negative and Gram positive ID/AST or AST only Phoenix panels. Ofloxacin 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 antimicrobic.
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. For each isolate, an inoculum suspension equivalent to a 0.5 McFarland standard is prepared in the Phoenix ID broth. more to inoculating the Phoenix AST broth, one drop of Phoenix AST indicator solution is added to the uninoculated AST broth. The AST broth is then inoculated using the organism suspension from the ID broth. The Phoenix antimicrobial susceptibility test is inoculated with the AST broth. Inoculated panels are loaded into the Phoenix instrument.
The Phoenix AST method is a broth based microdilution test. The Phoenix system utilizes a redox indicator for the detection of organism growth in the presence of an antimicrobial agent. Measurements of changes to the indicator as well as bacterial turbidity are used in the determination of bacterial growth. Each AST panel configuration contains several antimicrobial agents with a wide range of two-fold doubling dilution concentrations.
The instrument houses the panels where they are continuously incubated at a nominal temperature of 35°C. The instrument takes readings of the panels every 20 minutes. The tentifyerature of 50 €. The nive an identification of the isolate, minimum inhibitory concentration (MIC) values and category interpretations, S, I, or R (sensitive, intermediate, and resistant).
Here's a summary of the acceptance criteria and study details for the BD Phoenix™ Automated Microbiology System, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criterion (Primary Endpoint for Equivalence) | Target Performance | Reported Device Performance (Ofloxacin) |
|---|---|---|
| Essential Agreement (EA) with reference method | > 90% | > 90% (for all three drugs, including Ofloxacin) |
| Category Agreement (CA) with reference method | Not explicitly stated as a minimum percentage in the provided text, but implied as a key metric for substantiating equivalence. | Reported alongside EA. No specific minimum percentage for CA was given but the statement "Phoenix panels demonstrated essential agreement of > 90% to the expected/reference results for all three drugs" and subsequent tables imply acceptable CA for equivalence. |
| Intra-site Reproducibility (MIC results) | Not explicitly stated, but clinical study results deemed acceptable for equivalence. | > 90% (for both gram-negative and gram-positive isolates tested with Ofloxacin) |
| Inter-site Reproducibility (MIC results) | Not explicitly stated, but clinical study results deemed acceptable for equivalence. | > 95% (for both gram-negative and gram-positive isolates tested with Ofloxacin) |
Notes on the Table:
- The document states that the evaluation was "as defined in the FDA Draft guidance document, 'Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices', March 8, 2000." This guidance document would contain the specific acceptance criteria for EA and CA, which are summarized as "substantially equivalent performance" if the criteria are met. The text here only specifically quantifies >90% EA.
- "All three drugs" refers to the drug(s) tested apart from Ofloxacin. The document specifically provides data for Ofloxacin.
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size:
- Clinical Studies (Challenge & Clinical Isolates): The exact number of isolates for each organism/antimicrobic combination is not explicitly stated. The study involved "Challenge set isolates" and "clinical isolates."
- Reproducibility Studies: For Ofloxacin, the study involved panels of gram-negative and gram-positive isolates. Each site tested the isolates in triplicate on three different days. The total number of unique isolates is not given, but it implies a significant number to assess reproducibility across 6 sites.
- Data Provenance:
- Clinical Studies: Conducted at "ten geographically diverse sites across the United States." The data is prospective for clinical isolates and retrospective for challenge isolates (as they have "expected results").
- Reproducibility Studies: Conducted at "six external sites" (three for gram-negative, three for gram-positive). The data provenance is broadly "external sites."
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- Ground Truth for Clinical Isolates: The ground truth was established by the "NCCLS broth microdilution method," which is a standardized laboratory method. This does not involve "experts" in the sense of clinicians making subjective interpretations. Rather, it relies on the established accuracy and reproducibility of the NCCLS method performed by qualified laboratory personnel.
- Ground Truth for Challenge Isolates: The ground truth was "expected results for each organism/antimicrobic combination." This implies a pre-defined standard, likely based on established reference methods or expert consensus in microbiology, but the specific number or qualifications of experts are not mentioned.
4. Adjudication Method for the Test Set
- No explicit adjudication method (e.g., 2+1, 3+1) is mentioned. The comparison is directly between the BD Phoenix System results and the NCCLS reference broth microdilution method (for clinical isolates) or "expected results" (for challenge isolates). Discrepancies would typically be reviewed by laboratory personnel according to standard operating procedures, but a formal adjudication process involving multiple external experts for disagreements 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
- No. This study is for an automated microbiology system that determines antimicrobial susceptibility (MIC values and categories) and organism identification, not a diagnostic imaging device involving human readers' interpretation. Therefore, an MRMC study and analysis of human reader improvement with AI assistance are not applicable. The device replaces manual interpretation of susceptibility testing rather than assisting it.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done
- Yes, this was a standalone performance study. The BD Phoenix™ Automated Microbiology System is an automated system where the instrument takes readings and provides results (identification, MICs, and interpretations) without direct human intervention in the interpretation process of each individual test result. Humans load the panels and interpret the final output from the system, but the core measurement and interpretation for susceptibility are automated. The comparison is between this automated system's output and a reference method.
7. The Type of Ground Truth Used
- For Clinical Isolates: The ground truth was established by the NCCLS broth microdilution method, which is a widely accepted, standardized reference method for antimicrobial susceptibility testing.
- For Challenge Isolates: The ground truth was "expected results," which implies a pre-defined standard based on established microbiological principles or expert consensus in such panels.
8. The Sample Size for the Training Set
- The document does not explicitly mention a "training set" in the context of machine learning model development. This is an older 510(k) (2002) for an automated microbiology system that likely relies on rule-based algorithms or statistical models built from extensive prior research and data, rather than a deep learning model requiring a distinct, large training set as understood today. The data described (analytical and clinical studies) appears to be primarily for verification and validation.
9. How the Ground Truth for the Training Set Was Established
- As mentioned above, a "training set" for a machine learning model is not explicitly discussed. The system's underlying capabilities (e.g., how it interprets redox changes and turbidity to determine growth/MIC) would have been developed based on extensive microbiology research and correlation with reference methods over time. The "ground truth" for developing the system's internal algorithms would have relied on data from reference methods (like microbroth dilution) and known biological responses of microorganisms to antimicrobials.
§ 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.”