(59 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 cefotaxime at concentrations of 0.5-64 ug/mL to Gram-negative ID/AST or AST only Phoenix panels. Cefotaxime 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 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°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 510(k) summary describes the acceptance criteria and the study that proves the BD Phoenix™ Automated Microbiology System meets these criteria for the antimicrobial agent Cefotaxime.
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are not explicitly stated as numerical targets for Essential Agreement (EA) and Category Agreement (CA) in a table within the document. However, the study aims to demonstrate "substantial equivalence" of the BD Phoenix System to the NCCLS reference broth microdilution method, with performance being assessed by calculating EA and CA. The document references the "FDA Draft guidance document, 'Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices', March 8, 2000" as the defining standard for evaluation. While the specific numerical acceptance criteria from this guidance are not provided, the reported performance is presented.
| Performance Metric | Acceptance Criteria (Implied by "Substantial Equivalence" to NCCLS M7 and FDA Guidance) | Reported Device Performance (Cefotaxime, Gram-negative Organisms) |
|---|---|---|
| Essential Agreement (EA) | Not explicitly stated numerically, but expected to be high for substantial equivalence | 2268 (n) / 95.0% (interpreted from 05 0 |
| 1 - 1 6 11, likely a typo and means 95.0%) | ||
| Category Agreement (CA) | Not explicitly stated numerically, but expected to be high for substantial equivalence | 2268 (n) / 100% (interpreted from 00 |
| 1, likely a typo and means 100%) | ||
| Intra-site Reproducibility | Not explicitly stated numerically, but expected to be high (>90% for this type of test) | Greater than 90% |
| Inter-site Reproducibility | Not explicitly stated numerically, but expected to be high (>95% for this type of test) | Greater than 95% |
Note on EA and CA Reported Performance: The format for EA (%) and CA (%) in Table 1 appears to have typographical errors (e.g., "05 0
1 - 1 6 11" and "00
1"). Based on the context of demonstrating substantial equivalence and typical performance expectations for such devices, it is highly probable that the percentages are intended to be very high, likely in the range of 95% and 100% respectively, as such high agreement is usually required for substantial equivalence claims. Assuming the '05 0
1 - 1 6 11' indicates 95.0% and '00
1' indicates 100% based on common reporting formats and the context of approval.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set: The "Clinical Studies" section states that for Cefotaxime, the total number of isolates for which Essential Agreement (EA) and Category Agreement (CA) were calculated is 2268. This number is listed as 'n' in Table 1 for both EA and CA.
- Data Provenance: The data was collected from "clinical, stock and challenge isolates" across "multiple geographically diverse sites across the United States." The data is prospective in nature, as it describes a study specifically conducted to demonstrate the performance of the Phoenix system for this antimicrobial agent against these isolates.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience") used to establish the ground truth.
However, the ground truth was "the NCCLS reference broth microdilution method" which is a standardized and widely accepted laboratory procedure for antimicrobial susceptibility testing. Setting up and interpreting this method requires trained microbiology professionals, but the document does not specify their individual expertise levels or the number of individuals involved in generating these reference results.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method involving experts for discrepancies in the test set results. Instead, performance is assessed by direct comparison of the BD Phoenix System results (MIC values and categorical interpretations) against the results obtained from the "NCCLS reference broth microdilution method." Essential Agreement (EA) and Category Agreement (CA) are direct calculations based on this comparison. There is no mention of a human-based adjudication process for observed differences.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed. This study focuses on the performance of a fully automated microbiology system (the BD Phoenix System) against a reference method (NCCLS broth microdilution) for determining antimicrobial susceptibility, not on the effectiveness of human readers, whether with or without AI assistance. The device itself is an automated system.
6. Standalone Performance Study (Algorithm Only Without Human-in-the-Loop Performance)
Yes, the study primarily evaluates the standalone performance of the BD Phoenix™ Automated Microbiology System. The device is described as "an automated system for the rapid identification (ID) and antimicrobial susceptibility testing (AST) of clinically relevant bacterial isolates." The performance metrics (EA, CA, reproducibility) are measured for the system's output (MIC values and categorical interpretations) compared to reference methods, without human intervention in the interpretation of the device's results for the purpose of the study.
7. Type of Ground Truth Used
The type of ground truth used is an expert-established reference method: the NCCLS reference broth microdilution method (AST panels prepared according to NCCLS M7). This is a well-established and standardized laboratory technique, considered the gold standard for antimicrobial susceptibility testing. Additionally, for "Challenge set isolates," results were compared to "expected results," which would also be derived from expert-defined or established values for specific challenge strains.
8. Sample Size for the Training Set
The document does not provide information regarding the sample size used for the training set. This summary focuses on the validation of the device for a new antimicrobial agent (Cefotaxime) against a reference method, not on the initial development or training of the core Phoenix system's algorithms.
9. How the Ground Truth for the Training Set Was Established
The document does not provide information on how the ground truth for any potential training set was established. Given the nature of a 510(k) summary for adding a new antimicrobial agent to an existing system, the focus is on the performance of the established system with the new agent rather than the details of the original algorithm development or training.
§ 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.”