(68 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 imipenem at concentrations of 1-16 ug/mL to Gram-negative ID/AST or AST only Phoenix panels. Imipenem 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℃. 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 the study details for the BD Phoenix™ Automated Microbiology System - Imipenem 1-16 µg/mL, based on the provided document:
Acceptance Criteria and Device Performance
| Acceptance Criteria | Reported Device Performance (Imipenem) |
|---|---|
| Overall Intra-site Reproducibility (>90%) | >90% |
| Overall Inter-site Reproducibility (>95%) | >95% |
| Essential Agreement (EA) with Reference | 97.2% (n=2680) |
| Category Agreement (CA) with Reference | 96.8% (n=2680) |
Study Details
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Sample size used for the test set and the data provenance:
- Sample Size: 2680 isolates for Essential Agreement (EA) and Category Agreement (CA).
- Data Provenance: Clinical, stock, and challenge isolates. These were collected across multiple geographically diverse sites across the United States. The study compared Phoenix System results to expected results (for challenge isolates) and to the NCCLS reference broth microdilution method (for clinical isolates).
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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. The ground truth for clinical isolates was established by the NCCLS reference broth microdilution method, which is a standardized laboratory procedure, not typically expert consensus in the way a radiologist might interpret an image. For challenge isolates, "expected results" were used, which implies a known truth for those specific strains.
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Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- The document does not describe an adjudication method in the context of expert review. The comparison was primarily against a reference laboratory method (NCCLS broth microdilution) or pre-determined expected results for challenge isolates.
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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:
- This was not an MRMC comparative effectiveness study involving human readers with or without AI assistance. The device itself is an automated system for antimicrobial susceptibility testing; it assists microbiologists by automating a lab process, not by interpreting results that would otherwise be interpreted by a human expert in the same way a radiologist reads an image.
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If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, the performance presented (EA and CA) is for the standalone device (BD Phoenix™ Automated Microbiology System) compared to the reference method. While a human inoculates the panel and inputs it into the system, the interpretation of results (MIC values and categories S, I, R) is automated by the device's software.
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The type of ground truth used:
- Reference Method: For clinical isolates, the ground truth was established using the NCCLS reference broth microdilution method (AST panels prepared according to NCCLS M7).
- Expected Results: For challenge isolates, "expected results" were used, implying a pre-defined or known susceptibility profile for those specific challenge strains.
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The sample size for the training set:
- The document does not explicitly state the sample size for the training set. It describes the "Clinical Studies" and "Site Reproducibility" for validation, but does not differentiate or quantify a separate training set. Given the context of a 510(k) for an automated lab instrument, the development and verification/validation processes might involve internal data sets not explicitly detailed in this summary.
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How the ground truth for the training set was established:
- As the training set size is not specified, the method for establishing its ground truth is also not explicitly detailed. However, for such devices, it would typically involve similar reference methods (like NCCLS broth microdilution) to develop and calibrate the algorithms that interpret the redox indicator changes and bacterial turbidity.
§ 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.”