(28 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 addition of the antimicrobial agent cefoxitin at concentrations of 0.5-64 ug/mL to gram-negative ID/AST or AST only Phoenix panels. Cefoxitin 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 spp. (including K. pneumoniae) Morganella morganii
Proteus mirabilis Proteus vulgaris Providencia spp. (including P. rettgeri)
Active In Vitro Against:
Klebsiella oxytoca
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 inoculation 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℃. 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 an analysis of the provided text, focusing on the acceptance criteria and the study that proves the device meets them:
1. Table of Acceptance Criteria and the Reported Device Performance:
The document doesn't explicitly state numerical acceptance criteria in a dedicated table format. However, it implies the acceptance criteria through the performance metrics evaluated during the clinical studies. The core performance metrics discussed are Essential Agreement (EA) and Category Agreement (CA), which are compared to a reference method (NCCLS broth microdilution).
| Acceptance Criteria (Implied) | Reported Device Performance (Summary from Table 1) |
|---|---|
| Essential Agreement (EA): BD Phoenix result agrees exactly or within + one two-fold dilution of the reference. | (Specific numerical values for EA and CA are redacted in the provided Table 1, but the text states the "Performance of BD Phoenix System for Gram-Negative Organisms by Drug Table 1" summarizes it.) |
| Category Agreement (CA): BD Phoenix result agrees with the reference method regarding FDA categorical interpretive criteria (susceptible, intermediate, and resistant). | ("Table 1 summarizes the performance for the isolates tested in this study.") |
| Intra-site reproducibility: > 90% | > 90% (overall intra-site reproducibility for gram-negative isolates) |
| Inter-site reproducibility: > 95% | > 95% (overall inter-site reproducibility for gram-negative isolates) |
2. Sample Sizes Used for the Test Set and the Data Provenance:
- Test Set Sample Size: The document does not provide a specific total number of isolates for the "Clinical Studies" test set. It mentions "Clinical, stock and challenge isolates were tested." Table 1 likely contained this specific number under the 'n' column, but that information is redacted.
- Data Provenance: The data was gathered from "multiple geographically diverse sites across the United States." This indicates the data is prospective clinical observational data, supplemented by "stock and challenge isolates."
3. 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 for establishing ground truth for the test set.
- The ground truth for clinical isolates was established by the "NCCLS reference broth microdilution method," which is a laboratory standard rather than a human expert consensus.
- For "Challenge set isolates," results were compared to "expected results," implying pre-determined reference values rather than expert adjudication.
4. Adjudication Method for the Test Set:
- There was no stated adjudication method involving human experts for the test set. The comparison was primarily against the "NCCLS reference broth microdilution method" for clinical isolates and "expected results" for challenge isolates.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done:
- No, an MRMC comparative effectiveness study was not done. The study's objective was to demonstrate substantial equivalence of the automated system to a reference laboratory method (NCCLS broth microdilution), not to compare human reader performance with and without AI assistance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done:
- Yes, a standalone study was done. The entire study assesses the performance of the "BD Phoenix™ Automated Microbiology System" (algorithm/device only) against a reference method. It's designed to show the device's ability to accurately determine antimicrobial susceptibility without human interpretative intervention in the final result generation for MIC values and category interpretations.
7. The Type of Ground Truth Used:
- For clinical isolates: The ground truth was established by the NCCLS reference broth microdilution method. This is a well-established, standardized laboratory method.
- For challenge isolates: The ground truth was based on "expected results," which typically refers to isolates with known, well-characterized antimicrobial susceptibility patterns.
8. The Sample Size for the Training Set:
- The document does not provide any information regarding a "training set" or its sample size. This is typical for a 510(k) submission for a device like this, which likely relies on pre-defined algorithms and libraries rather than ongoing machine learning model training in the conventional sense. The core method (broth microdilution with redox indicator) is a well-established principle.
9. How the Ground Truth for the Training Set Was Established:
- As no training set is mentioned, the method for establishing its ground truth is not applicable/not provided.
§ 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.”