(35 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 cefotaxime at concentrations of 0.0625-4 ug/mL to Streptococcus ID/AST or AST only Phoenix panels. Cefotaxime has been shown to be active in viro 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:
Streptococcus pneumoniae
Streptococcus pyogenes (Group A beta-hemolytic streptococci)
Streptococcus spp.
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. For testing Streptococcus species 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-S Broth used for performing AST tests only. .
- BD Phoenix AST-S 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, 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 with Cefotaxime for Streptococcus, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implicit from FDA Guidance & Substantial Equivalence Goal) | Reported Device Performance (Summary) |
|---|---|---|
| Site Reproducibility | >95% (Generally accepted standard for AST systems) | Intra-site: ≥97.9% |
| Inter-site: 99.3% | ||
| Essential Agreement (EA) | No explicit numerical threshold, but expected to be high for substantial equivalence | High (Exact figures not explicitly stated in combined table, but "Performance of BD Phoenix System for Streptococcal Organisms by Drug Table 1" implies high agreement with reference method) |
| Category Agreement (CA) | No explicit numerical threshold, but expected to be high for substantial equivalence | High (Exact figures not explicitly stated in combined table, but "Performance of BD Phoenix System for Streptococcal Organisms by Drug Table 1" implies high agreement with reference method) |
| Accuracy (MIC) | Within ± one two-fold dilution compared to reference method | "Within ± 1 dilution" (Reproducibility section refers to this, accuracy is implicitly met by EA) |
| Reproducibility (MIC) | 95% within ± 1 dilution (Generally accepted standard for AST systems) | 99.3% within ± 1 dilution |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size:
- Clinical Studies: The text mentions "Clinical, stock and challenge isolates were tested." No specific total number is provided for the combined clinical and challenge isolates.
- Site Reproducibility: A "panel of streptococcal isolates" was used. The exact number is not specified, but each site tested in triplicate on three different days.
- Data Provenance: Retrospective and prospective (implied by "Clinical, stock and challenge isolates were tested across multiple geographically diverse sites across the United States"). Clinical isolates are typically prospective, collected as part of the study, while stock and challenge isolates can be retrospective or prepared for the study.
- Country of Origin: United States ("across multiple geographically diverse sites across the United States").
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications of those Experts
- The document does not mention the number or qualifications of experts for establishing ground truth. The ground truth for the test set was established by performing the CLSI reference broth microdilution method. This method is a recognized standard, so the "experts" are the trained laboratory personnel performing these reference methods, rather than clinical specialists like radiologists.
4. Adjudication Method for the Test Set
- No specific adjudication method is mentioned for the test set. The comparison was directly between the BD Phoenix System results and the CLSI reference broth microdilution method results.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted. This study focuses on the performance of an automated susceptibility testing system against a reference laboratory method, not on human readers or the effect of AI on human reader performance.
6. Standalone Performance Study (i.e., algorithm only without human-in-the-loop performance)
- Yes, this study is a standalone performance study. The BD Phoenix System is an automated system where the algorithm/software interprets readings to provide MIC values and category interpretations. The performance metrics (Essential Agreement, Category Agreement, Reproducibility) are calculated solely based on the system's output compared to the reference method, without human intervention in the interpretation phase for the test.
7. Type of Ground Truth Used
- The primary ground truth used was the CLSI reference broth microdilution method. For challenge isolates, "expected results" were used, which would typically be established by known characteristics or prior testing using recognized reference methods.
8. Sample Size for the Training Set
- The document does not specify a separate training set or its sample size. The description of the System focuses on its performance evaluation rather than its development/training data. Automated microbiology systems typically use extensive historical data and expert-defined rules during their development and initial "training" phases, but these details are not provided in a 510(k) summary focused on validation.
9. How the Ground Truth for the Training Set Was Established
- As a training set is not explicitly mentioned, the method for establishing its ground truth is not provided. However, for the development of such an automated system, the ground truth would typically be established through:
- Large datasets of previous cultures with confirmed identifications and antimicrobial susceptibility results obtained via established reference methods (like CLSI broth microdilution).
- Expert consensus and clinical input to define interpretive criteria and rules for algorithmic determination.
- Pathology and clinical outcomes data might inform the clinical relevance of certain susceptibility profiles, influencing the system's interpretive guidelines over time.
§ 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.”