(48 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 antimicrobial Clindamycin at concentrations of 0.125-8 µg to Gram positive ID/AST or AST only Phoenix panels. Clindamycin 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.
Active In Vitro and in Clinical Infections Against:
Aerobic Gram-positive microorganisms Staphylococcus aureus
Active In Vitro Against:
Aerobic Gram-positive microorganisms Staphylococcus epidermidis
Results for Clindamycin should not be reported for staphylococci recovered from the urinary tract.
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 isolation equivalent to 0.5 McFarland standard is prepared in Phoenix ID broth.
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 readings are interpreted to give 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 the study that proves the device meets them, based on the provided text:
Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Metric) | Target Performance | Reported Device Performance | Comments |
|---|---|---|---|
| Essential Agreement (EA) | Not explicitly stated, implied to be high for "substantially equivalent" | 98.2% | EA occurs when the BD Phoenix™ System agrees exactly or within ± one two-fold dilution to the reference result. |
| Category Agreement (CA) | Not explicitly stated, implied to be high for "substantially equivalent" | 98.7% | CA occurs when the BD Phoenix™ System agrees with the reference method with respect to FDA categorical interpretive criteria (S, I, R). |
| Intra-site Reproducibility | > 90% | > 90% | For Clindamycin in the BD Phoenix System, tested at three sites. |
| Inter-site Reproducibility | > 95% | > 95% | For Clindamycin in the BD Phoenix System, tested at three sites. |
Study Details
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Sample size used for the test set and the data provenance:
- Test Set Sample Size: 1242 isolates (combined clinical, stock, and challenge isolates).
- Data Provenance: The study used "clinical, stock and challenge isolates" tested "across multiple geographically diverse sites across the United States." This indicates a prospective data collection from various locations within the United States.
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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.
- The ground truth for clinical isolates was established by comparison to the NCCLS reference broth microdilution method. For challenge isolates, the ground truth was "expected results." This implies that the reference method itself (NCCLS broth microdilution) is considered the gold standard, overseen by trained lab personnel, rather than interpretation by individual "experts" in the typical clinical sense (e.g., radiologists).
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Adjudication method for the test set:
- The document does not explicitly mention an adjudication method like 2+1 or 3+1. The performance was assessed by direct comparison of the Phoenix System results to the reference NCCLS method or expected results.
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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 study was not done. This study assesses the performance of an automated microbiology system (BD Phoenix) against a reference laboratory method (NCCLS broth microdilution), not the performance of human readers with or without AI assistance. This is an in vitro diagnostic device, not an image interpretation AI.
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If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Yes, a standalone study was done. The entire evaluation focuses on the performance of the "BD Phoenix™ Automated Microbiology System" (the device/algorithm) in determining antimicrobial susceptibility. The results (EA and CA) are presented for the system itself, without direct human intervention in the result interpretation once the system processes the sample.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The ground truth for clinical isolates was established by comparison to the NCCLS reference broth microdilution method.
- The ground truth for challenge isolates was based on "expected results," which are typically derived from well-characterized strains with known susceptibility profiles.
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The sample size for the training set:
- The document does not specify the sample size for a training set. This type of device (an automated microbiology system based on microdilution and redox indicators) likely uses a pre-defined algorithm and measurement thresholds, rather than being "trained" in the machine learning sense on a large dataset of isolates. Its "training" would be more akin to defining the physical and chemical parameters for detection and interpretation.
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How the ground truth for the training set was established:
- As noted above, a distinct "training set" in the machine learning context is not explicitly mentioned. The system's operational principles (redox indicator, turbidity changes, two-fold dilution concentrations) are based on established microbiological principles. The validation against the NCCLS reference method serves as the primary performance demonstration, rather than a separate training and testing paradigm typical of machine learning.
§ 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.”