(39 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, Enterococcus and Streptococcus.
This premarket notification is for Piperacillin at concentrations of 2-128 µg/mL to Gram-negative ID/AST or AST only Phoenix panels with the removal of the limitations for Proteus mirabilis, Providencia species and Stenotrophomonas maltophilia. Piperacillin 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.
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 Phocnix 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 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 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 in the instrument.
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 readings are interpreted to give an identification of the isolate, minimum inhibitory concentration (MIC) values and category interpretations, S, I, or R (sensitive, intermediate, or resistant).
Here's a breakdown of the acceptance criteria and study information based on the provided text:
Acceptance Criteria and Device Performance
The core of the acceptance criteria for this device, a susceptibility testing system, revolves around two key metrics: Essential Agreement (EA) and Category Agreement (CA). These are standard in antimicrobial susceptibility testing (AST) device evaluations. The reported performance for Piperacillin for Gram-Negative Organisms is included in the table.
| Acceptance Criteria Metric | Definition | Reported Device Performance (Piperacillin for Gram-Negative Organisms) |
|---|---|---|
| Essential Agreement (EA) | BD Phoenix™ Automated Microbiology System agrees exactly or within ± one two-fold dilution to the reference result. | ≥ 90% (implied, not explicitly stated as a target, but typical industry standard for AST devices) |
| Category Agreement (CA) | BD Phoenix™ Automated Microbiology System agrees with the reference method with respect to the FDA categorical interpretive criteria (susceptible, intermediate, and resistant). | ≥ 90% (implied, not explicitly stated as a target, but typical industry standard for AST devices) |
| Intra-site Reproducibility | Consistency of results within a single testing site. | > 90% |
| Inter-site Reproducibility | Consistency of results across different testing sites. | > 95% |
Note on Reported Performance: The provided table (Table 1) under "Performance of BD Phoenix System for Gram-Negative Organisms by Drug" is highly unreadable and appears to be corrupted or poorly formatted. Therefore, the specific numerical values for EA and CA for Piperacillin are not extractable from the provided text. However, the text explicitly states that the study results demonstrate substantially equivalent performance and that reproducibility was greater than 90% for intra-site and greater than 95% for inter-site, suggesting that the EA and CA likely met or exceeded the generally accepted >= 90% threshold for AST devices.
Study Details
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Sample Size Used for the Test Set and Data Provenance:
- Sample Size: Not explicitly stated in terms of a specific number for the test set. The study tested "Clinical, stock and challenge isolates."
- Data Provenance: "across multiple geographically diverse sites across the United States." The study included both "Clinical isolates" (likely prospective, collected during routine clinical practice) and "stock and challenge isolates" (retrospective, from laboratory collections or spiked for specific testing).
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Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:
- The ground truth for the clinical isolates was established by the CLSI reference broth microdilution method. This is a laboratory standard method, not typically performed or interpreted by individual "experts" in the context of radiologists or pathologists. The CLSI method itself is the "expert" reference standard.
- For "Challenge set isolates," results were compared to "expected results," which would have been pre-determined by an established method or expert consensus for those specific strains. No specific number or qualification of experts is mentioned.
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Adjudication Method for the Test Set:
- Not applicable as the ground truth was established by the CLSI reference broth microdilution method for clinical isolates and "expected results" for challenge isolates. These are objective laboratory methods; there is no mention of human adjudication for discrepancies between methods.
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Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- No, an MRMC comparative effectiveness study was not conducted. This study focuses on comparing the automated device's performance against a reference laboratory method, not on human reader performance with or without AI assistance.
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Standalone Performance (Algorithm Only Without Human-in-the-loop Performance):
- Yes, this was a standalone performance study. The BD Phoenix™ Automated Microbiology System is an automated device, and its performance was evaluated directly against a reference method (CLSI broth microdilution). Humans prepare the samples and load the panels, but the determination of MIC values and categorical interpretations is performed solely by the instrument's algorithm.
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Type of Ground Truth Used:
- For clinical isolates: CLSI reference broth microdilution method. This is a gold standard laboratory method for antimicrobial susceptibility testing.
- For challenge set isolates: Expected results. These are pre-defined results for known strains, typically established through rigorous characterization using reference methods.
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Sample Size for the Training Set:
- The document does not explicitly state a sample size for a "training set." The BD Phoenix system is a commercial product, and the mechanism for internal algorithm development (training) is not detailed in this 510(k) summary, which focuses on validation data for a specific antimicrobial agent addition. The clinical studies described are for validation, not training.
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How the Ground Truth for the Training Set Was Established:
- As no explicit "training set" is mentioned in the context of this 510(k) summary, how its ground truth was established is not provided. The summary focuses on the validation of the device for a new antimicrobial agent using existing reference methods as the ground truth for validation.
§ 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.”