(49 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 chloramphenicol at concentrations of 1 - 32 µg/mL to Gram Positive ID/AST or AST only Phoenix panels. Chloramphenicol 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 . or 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. Mcasurements 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, R or N (susceptible, intermediate, resistant or not susceptible).
Here's a summary of the acceptance criteria and study details for the BD Phoenix™ Automated Microbiology System Chloramphenicol - GP, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implied by the "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices", March 8, 2000, which requires demonstration of "substantially equivalent performance" to a reference method. The primary metrics for this equivalence are Essential Agreement (EA) and Category Agreement (CA). While the specific numerical thresholds for acceptance (e.g., >90% EA, >95% CA) are not explicitly stated as "acceptance criteria" within the provided text, they are the standard performance targets for such devices.
| Metric | Acceptance Criteria (Implied/Standard) | Reported Device Performance (Gram-Positive Organisms) |
|---|---|---|
| Essential Agreement (EA) | High percentage (typically >90%) | Not explicitly stated in Table 1; overall deemed "substantially equivalent" |
| Category Agreement (CA) | High percentage (typically >95%) | Not explicitly stated in Table 1; overall deemed "substantially equivalent" |
| Intra-site Reproducibility | >90% | >90% |
| Inter-site Reproducibility | >95% | >95% |
Note: Table 1 in the document is incomplete and does not show the specific EA and CA percentages for chloramphenicol against Gram-positive organisms. It only mentions that performance was assessed by calculating EA and CA.
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size: Not explicitly stated as a single number.
- It included "Clinical, stock and challenge isolates."
- "Challenge set isolates" were compared to expected results.
- "Clinical isolates" were compared to the NCCLS reference broth microdilution method.
- Data Provenance: Multiple geographically diverse sites across the United States. The study design included both "clinical" and "stock and challenge" isolates, suggesting a mix of prospectively collected (clinical) and retrospectively curated (stock/challenge) data.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
Not explicitly stated. The ground truth for clinical isolates was established by the NCCLS reference broth microdilution method, which is a standardized laboratory procedure, not typically dependent on individual expert interpretation in the same way an imaging study would be. For challenge set isolates, "expected results" implies a predetermined, validated reference.
4. Adjudication Method for the Test Set
Not applicable in the human reader sense. The comparison was primarily against a reference laboratory method (NCCLS broth microdilution) for clinical isolates and "expected results" for challenge isolates. The process is a direct comparison of quantitative MIC values and categorical interpretations.
5. 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
Not applicable. This device is an automated system for antimicrobial susceptibility testing, replacing manual methods or providing rapid results. It is not an AI-assisted diagnostic device where human readers are interpreting outputs. Therefore, an MRMC study and effects on human reader improvement are not relevant to this submission.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, this was a standalone performance study. The BD Phoenix System is an automated device designed to determine antimicrobial susceptibility independently. Its performance was directly compared to the NCCLS reference method.
7. The Type of Ground Truth Used
- For clinical isolates: NCCLS reference broth microdilution method. This is a well-established, standardized laboratory method considered the gold standard for antimicrobial susceptibility testing.
- For challenge isolates: "Expected results." These are typically results obtained from a well-characterized set of strains with known resistance patterns, often by multiple validated methods.
8. The Sample Size for the Training Set
Not applicable. This document describes the validation of a deterministic automated system, not a machine learning or AI algorithm in the contemporary sense that would require a distinct "training set" for model development. The system utilizes dried reagents and a redox indicator for growth detection based on established microbiological principles.
9. How the Ground Truth for the Training Set Was Established
Not applicable for the reasons stated in point 8.
§ 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.”