(43 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 acrobic 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 antimicrobial agent cephalothin at concentrations of 1-64 ug/mL to Gram-negative ID/AST or AST only Phoenix panels. cephalothin 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 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).
Here's a breakdown of the acceptance criteria and study information for the BD Phoenix™ Automated Microbiology System for Cephalothin, based on the provided 510(k) summary:
1. Table of Acceptance Criteria and Reported Device Performance
The study compares the BD Phoenix™ System's performance to the NCCLS reference broth microdilution method. The acceptance criteria are implicitly based on the FDA Draft guidance document, "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices", March 8, 2000, which requires demonstration of "substantially equivalent performance". The key metrics are Essential Agreement (EA) and Category Agreement (CA). While specific numerical thresholds for acceptance (e.g., >90% EA and CA) aren't explicitly stated in the summary, these are typical industry standards for demonstrating substantial equivalence.
| Metric (Acceptance Criteria) | Reported Device Performance (Cephalothin - Gram-negative Organisms) |
|---|---|
| Essential Agreement (EA) | 95.9% (on 1206 isolates) |
| Category Agreement (CA) | 82.8% (on 1206 isolates) |
| Intra-site reproducibility | >90% |
| Inter-site reproducibility | >95% |
2. Sample size used for the test set and the data provenance
- Sample Size for Test Set: 1206 isolates (combining clinical, stock, and challenge isolates).
- Data Provenance: The isolates were tested "across multiple geographically diverse sites across the United States". This indicates prospective data collection from clinical settings, 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 ground truth was established by the NCCLS reference broth microdilution method. This is a standardized laboratory procedure, not an expert consensus. Therefore, the concept of "number of experts" and "qualifications of experts" as typically applied to image analysis or diagnostic interpretation does not directly apply here. The experts involved would be laboratory personnel skilled in performing and interpreting the NCCLS method accurately.
4. Adjudication method for the test set
Not applicable. The ground truth is established by a standardized reference method (NCCLS broth microdilution), not through human interpretation requiring adjudication.
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
No, an MRMC comparative effectiveness study was not done. This device is an automated system for antimicrobial susceptibility testing, not an AI-assisted diagnostic tool that relies on human readers. The comparison is between an automated system and a reference laboratory method, not between human readers with and without AI assistance.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
Yes, this was a standalone study. The BD Phoenix™ Automated Microbiology System is itself an automated system ("algorithm only") that performs the susceptibility testing and provides interpretations (MIC values and S, I, or R categories) without direct human intervention in the interpretation phase for each reading. Its performance was compared directly to a "reference method" (NCCLS).
7. The type of ground truth used
The ground truth used was the NCCLS reference broth microdilution method. This is a widely accepted, standardized laboratory method for determining antimicrobial susceptibility.
8. The sample size for the training set
The document does not specify the sample size for a training set. This is a premarket notification (510(k)) that focuses on demonstrating substantial equivalence to a predicate device, rather than the internal development and training of the algorithm itself. It's common for 510(k) summaries to focus on validation rather than the details of initial development.
9. How the ground truth for the training set was established
Not specified, as the training set details are not provided. However, given the nature of the device, it's highly probable that any internal training or development would have relied on established reference methods (like NCCLS) or internal challenge strains with known susceptibility profiles.
§ 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.”