(38 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 tetracycline at concentrations of 0.5-16 µg/mL to Gram Positive ID/AST or AST only Phoenix panels. Tetracycline 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.
Active In Vitro and in Clinical Infections Against:
Staphylococcus aureus
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 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).
Here's a summary of the acceptance criteria and study details for the BD Phoenix™ Automated Microbiology System (Tetracycline 0.5-16 µg/mL), based on the provided text:
Acceptance Criteria and Device Performance
| Acceptance Criteria Category | Acceptance Criteria (from FDA Draft Guidance Document "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices", March 8, 2000) | Reported Device Performance |
|---|---|---|
| Essential Agreement (EA) | Not explicitly stated but generally indicates agreement within +/- one two-fold dilution compared to the reference method. | 1549 (n); 97.0% (Tetracycline) |
| Category Agreement (CA) | Not explicitly stated but generally indicates agreement with the reference method regarding susceptible, intermediate, or resistant categories. | 1549 (n); 96.6% (Tetracycline) |
| Intra-site Reproducibility | Greater than 90% | Greater than 90% |
| Inter-site Reproducibility | Greater than 95% | Greater than 95% |
Study Details
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Sample sizes used for the test set and the data provenance:
- Test Set Sample Size: 1549 isolates for Tetracycline (this number represents the 'n' for both EA and CA).
- Data Provenance:
- Country of Origin: United States ("multiple geographically diverse sites across the United States").
- Retrospective or Prospective: Not explicitly stated as retrospective or prospective. However, the study involved testing "Clinical, stock and challenge isolates," which suggests a mix of existing isolates (stock/challenge) and potentially newly collected 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:
- This information is not provided in the document. The ground truth (reference method) is the NCCLS reference broth microdilution method, not expert consensus.
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Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- Adjudication methods involving multiple human readers are not applicable here, as the comparison is between an automated system (BD Phoenix) and a standardized reference laboratory method (NCCLS broth microdilution). Therefore, "none" in the context of human reader adjudication.
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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:
- No, an MRMC comparative effectiveness study was not done. This study evaluates the performance of an automated susceptibility testing system against a reference method, not the performance of human readers with or without AI assistance.
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If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, a standalone study was done. The BD Phoenix System is an "Automated Microbiology System" and its performance was assessed directly against the NCCLS reference method. This represents the algorithm (system) performance without direct human interpretation in the determination of the MIC values and category interpretations from the Phoenix system readings, though human operators are involved in preparing samples and loading the system.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- Reference Laboratory Method: The ground truth was established using the NCCLS reference broth microdilution method (AST panels prepared according to NCCLS M7). This is a standardized, recognized laboratory method for determining antimicrobial susceptibility.
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The sample size for the training set:
- The document does not provide information about a separate training set or its sample size. The study describes the evaluation of the "Phoenix antimicrobial susceptibility test" and does not detail the development or training phase of the algorithm itself.
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How the ground truth for the training set was established:
- Since information about a specific training set is not provided, the method for establishing its ground truth is also not available in this document.
§ 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.”