(58 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-Enterobacceriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus and Enterococcus.
This premarket notification is for the antimicrobial agent trimethoprim-sulfamethoxazole at concentrations of 0.5/9.5-16/304 ug/mL to Gram-negative ID/AST or AST only Phoenix panels. trimethoprim-sulfamethoxazole 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 Klebsiella species Enterobacter species Morganella morganii
- Proteus mirabilis Proteus vulgaris Shigella flexneri Shigella sonnei
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 a 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, or resistant).
The provided document describes the 510(k) premarket notification for the BD Phoenix™ Automated Microbiology System (Phoenix System) for use with the antimicrobial agent Trimethoprim-sulfamethoxazole. The study's purpose is to demonstrate substantial equivalence to the NCCLS reference broth microdilution method for antimicrobial susceptibility testing (AST) of Gram-negative isolates.
Here's an breakdown of the acceptance criteria and the study details:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for the BD Phoenix System are based on demonstration of "substantially equivalent performance" compared to the NCCLS reference method. While specific numerical acceptance criteria (e.g., within X% agreement) are not explicitly stated in a table, the document highlights reproducibility as a key performance metric.
| Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Agreement with NCCLS Reference Broth Microdilution Method (AST) | "Substantially equivalent performance" | Demonstrated "substantially equivalent performance" |
| Intra-site Reproducibility | "Greater than 90%" (for the antimicrobial agent) | Achieved "greater than 90%" |
| Inter-site Reproducibility | "Greater than 95%" (for the antimicrobial agent) | Achieved "greater than 95%" |
2. Sample Size Used for the Test Set and Data Provenance
The document states that a "panel of Gram-negative isolates" was used for the site reproducibility study. However, the specific sample size (number of isolates) for the test set is not explicitly provided.
The data provenance is prospective, as the study involved testing isolates in triplicate on different days at three different sites using predetermined methods and a specific lot of panels and reagents. The document does not specify the country of origin of the data; however, it is submitted to the US FDA (Food and Drug Administration), implying the study was conducted to meet US regulatory requirements.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The ground truth for AST is established by the NCCLS reference broth microdilution method (AST panels prepared according to NCCLS M7). This method is a standardized laboratory procedure, not an expert consensus per se. Therefore, the concept of "number of experts" or their "qualifications" for establishing ground truth in this context is not applicable in the same way it would be for, for example, image interpretation. The "ground truth" is the result obtained from the established, validated reference laboratory method.
4. Adjudication Method for the Test Set
The document does not describe an "adjudication method" in the typical sense (e.g., 2+1 arbitrated by a third party). Instead, the study focused on reproducibility between different test runs (triplicate on three different days) and across different sites. The agreement between the Phoenix System and the NCCLS reference method would be assessed directly, rather than through an adjudication of interpretations.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and Effect Size
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This type of study typically involves human readers interpreting cases with and without AI assistance to measure the improvement in performance. The BD Phoenix System is an automated system for antimicrobial susceptibility testing, not an imaging or interpretive AI system that human readers would directly "improve" with. The comparison is between an automated system's output and a reference laboratory method.
6. If a Standalone (i.e., Algorithm Only Without Human-in-the-Loop Performance) Was Done
Yes, a standalone performance study was done. The BD Phoenix Automated Microbiology System is designed to provide results automatically, and the evaluation compared its automated output directly to the NCCLS reference method. There is no human "in the loop" for interpreting the results from the Phoenix System for the purpose of the primary performance evaluation. While a human loads the samples and reviews the final report, the core performance being evaluated is the algorithm's ability to determine MIC values and category interpretations.
7. The Type of Ground Truth Used
The type of ground truth used is the NCCLS reference broth microdilution method (AST panels prepared according to NCCLS M7). This is a well-established and standardized laboratory method for determining antimicrobial susceptibility, considered the gold standard for AST.
8. The Sample Size for the Training Set
The document does not provide information on the sample size for a training set. Automated microbiology systems like the Phoenix System are typically developed using extensive internal datasets and validation studies during their development, but the 510(k) summary focuses on the ultimate performance evaluation against a reference method rather than the specifics of its internal development and training.
9. How the Ground Truth for the Training Set Was Established
As no specific training set or its size is mentioned, the method for establishing ground truth for a training set is not described in this document. During the development of such a system, the ground truth for training would likely also be established through reference AST methods, similar to the validation process.
§ 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.”