(38 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 the addition of the antimicrobial agent cefazolin at concentrations of I mis promiser nombre ID/AST or AST only Phoenix panels. Cefazolin 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 Proteus mirabilis Klebsiella species Enterobacter acrogenes
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.
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, or resistant).
Acceptance Criteria and Study for BD Phoenix™ Automated Microbiology System – Cefazolin
This summary describes the acceptance criteria and the study that proves the BD Phoenix™ Automated Microbiology System, specifically for Cefazolin (0.5-32 µg/mL) with Gram-Negative ID/AST or AST only Phoenix panels, meets these criteria.
1. Table of Acceptance Criteria and Reported Device Performance
The core acceptance criteria for antimicrobial susceptibility testing systems are Essential Agreement (EA) and Category Agreement (CA) with a reference method.
| Acceptance Criteria (against CLSI Reference Broth Microdilution) | Reported Device Performance (Summary) |
|---|---|
| Essential Agreement (EA): The BD Phoenix™ Automated Microbiology System agrees exactly or within ± one two-fold dilution to the reference result. | Demonstrated performance by calculating EA. Specific percentage not provided in the excerpt for Cefazolin. |
| Category Agreement (CA): The BD Phoenix™ Automated Microbiology System agrees with the reference method with respect to the FDA categorical interpretive criteria (susceptible, intermediate, and resistant). | Demonstrated performance by calculating CA. Specific percentage not provided in the excerpt for Cefazolin. |
| Intra-site Reproducibility: Overall intra-site reproducibility of greater than 90%. | > 90% forgram-negative isolates tested. |
| Inter-site Reproducibility: Overall inter-site reproducibility greater than 95%. | > 95% for gram-negative isolates tested. |
Note: While the document states that performance was "assessed by calculating Essential Agreement (EA) and Category Agreement (CA)," and presents a "Table 1: Performance of BD Phoenix System for Gram-Negative Organisms by Drug," the table content provided is garbled and does not show specific numerical performance results for Cefazolin. Therefore, only the general statement of assessment and the qualitative result of "substantially equivalent" can be reported based on the provided text.
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly state the exact sample size for the test set. It mentions "Clinical, stock and challenge isolates were tested."
- Clinical isolates: These are typically fresh isolates obtained from patient samples.
- Stock isolates: Likely reference strains or strains maintained in a collection.
- Challenge isolates: These are often strains with known resistance mechanisms or unusual susceptibility patterns used to challenge the system's performance.
Data Provenance: The study was conducted "across multiple geographically diverse sites across the United States." This indicates prospective data collection in a multi-center setting within the United States.
3. Number of Experts Used to Establish Ground Truth and Qualifications
The document does not specify the number of experts used or their qualifications for establishing the ground truth for the test set.
4. Adjudication Method for the Test Set
The document does not describe a specific adjudication method beyond comparing Phoenix System results to the CLSI reference broth microdilution method. For challenge set isolates, results were compared "to the expected results." For clinical isolates, results were compared "to the results obtained from the CLSI reference broth microdilution method." This implies the reference method's result is taken as the ground truth without further expert adjudication mentioned.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was done. This study is focused on the device's accuracy against a recognized reference method, not on human reader performance with or without AI assistance.
6. Standalone Performance Study
Yes, a standalone performance study was done. The entire study describes the performance of the BD Phoenix™ Automated Microbiology System as an algorithm-only device (without human intervention in the MIC determination process) against the CLSI reference broth microdilution method. The instrument automatically interprets readings to give MIC values and category interpretations.
7. Type of Ground Truth Used
The primary ground truth used for performance evaluation was the CLSI reference broth microdilution method for clinical isolates. For "challenge set isolates," the ground truth was referred to as "expected results." This typically implies results obtained through a highly accurate and carefully controlled reference method or known characteristics of the challenge strains.
8. Sample Size for the Training Set
The document does not provide information about a separate "training set" or its sample size. This type of device's development typically involves an internal development and validation phase, but the provided text focuses on the pivotal substantial equivalence clinical study against the reference standard. The "training set" for the Phoenix system's internal algorithms would have been developed prior to this submission study.
9. How the Ground Truth for the Training Set was Established
As no explicit training set is mentioned in the provided text, the method for establishing its ground truth is not described. However, given the nature of AST device development, it is highly probable that the ground truth for any internal training data would have also been established using recognized reference methods for antimicrobial susceptibility testing, such as broth microdilution or agar dilution.
§ 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.”