(250 days)
The BD Phoenix™ Automated Microbiology System is intended for the in vitro rapid identification (ID) and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of Gram Negative aerobic and facultative anaerobic bacteria belonging to the family Enterobacteriaceae and non-Enterobacteriaceae.
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.
Ertapenem 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:
Escherichia coli Klebsiella pneumoniae Proteus mirabilis
Active In Vitro Citrobacter freundii Citrobacter koseri Enterobacter cloacae Klebsiella oxytoca (excluding ESBL producing isolates)
Morganella morganii Proteus vulgaris Providencia rettgen Providencia stuartii Serratia marcescens
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. Phoenix panels are inoculated with a specified organism density and placed into the instrument. Inoculum for use with the Phoenix system may be prepared either manually or may be automated using the BD Phoenix™ AP System.
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° ± 1°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 an analysis of the acceptance criteria and study details for the BD Phoenix™ Automated Microbiology System - Ertapenem (0.0625-8 µg/mL) based on the provided 510(K) summary:
Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Metric) | Performance Target (Implicit based on Summary) | Reported Device Performance (Ertapenem) |
|---|---|---|
| Essential Agreement (EA) | > 90% (Common FDA AST target) | 98.7% |
| Category Agreement (CA) | > 90% (Common FDA AST target) | 97.9% |
| Site Reproducibility | > 95% (+/- 1 dilution) agreement | > 95% (+/- 1 dilution) agreement |
Note: The document doesn't explicitly state the numerical acceptance criteria for EA and CA, but 90% is a common benchmark for FDA AST substantial equivalence. The "Conclusions Drawn from Substantial Equivalence Studies" section indicates that the performance met the requirements outlined in the FDA guidance document.
Study Details
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Sample size used for the test set and the data provenance:
- Test Set Sample Size: 1201 isolates (combined clinical and challenge isolates) for both Essential Agreement and Category Agreement.
- Data Provenance: Clinical, stock, and challenge isolates. The clinical isolates were collected across multiple geographically diverse sites across the United States. The document does not specify the country of origin for the stock or challenge isolates but implies they are also typical for US regulatory submissions. The study appears to be prospective in nature for new data collection, though it might integrate previously isolated stock cultures.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g., radiologist with 10 years of experience):
- The document does not specify the number of experts or their qualifications. The ground truth (reference method) was established by the CLSI reference broth microdilution method (AST panels prepared according to CLSI M7). This is a standardized laboratory procedure, not typically dependent on individual expert interpretation in the same way an imaging study would be.
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Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- Not applicable in the context of AST testing using a reference method. The CLSI reference method provides a definitive MIC result, which is then compared directly to the device's result. There is no human adjudication process for discrepancies described or implied, beyond standard laboratory quality control.
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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 type of study is primarily relevant for diagnostic imaging or interpretation tasks where human readers are making subjective assessments. In this AST device, the comparison is between the automated system and a standardized reference laboratory method.
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If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, the performance presented for the BD Phoenix™ Automated Microbiology System is standalone algorithm performance. The system automatically reads and interprets the results to give MIC values and category interpretations, which are then compared to the CLSI reference method's results. While laboratory personnel prepare the inoculum and load the panels, the interpretation of the AST panel reading is automated.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The ground truth used was the CLSI reference broth microdilution method (AST panels prepared according to CLSI M7). This is a highly standardized and accepted laboratory method for determining antimicrobial susceptibility, considered the "gold standard" for in vitro AST.
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The sample size for the training set:
- The document does not explicitly state the sample size for a training set. Manufacturers of AST systems typically develop and refine their algorithms using extensive internal datasets prior to clinical studies. The 510(k) summary focuses on the validation (test set) performance for regulatory submission rather than the full development process.
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How the ground truth for the training set was established:
- The document does not explicitly state how the ground truth for a training set was established. However, it is highly probable that if a training set were used to develop or refine the algorithm, its ground truth would also have been established using a similar, if not identical, CLSI reference broth microdilution method. This ensures consistency between the development and validation phases.
§ 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.”