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ETEST® is a manual, quantitative technique for determination of antimicrobial susceptibility of non-fastidious Gram-negative and Gram-positive aerobic bacteria. The system comprises a predefined antibiotic gradient which is used to determine the Minibitory Concentration (MC, in ug/mL) of different antimicrobial agents against microorganisms tested on agar media using overnight incubation.

Eravacycline has been shown to be active against most isolates of the microorganisms listed below according to this antimicrobial agent.

ETEST® ERV can be used to determine the MIC of Eravacycline against the following microorganisms:

Active both in vitro and in clinical infections:

Gram-negative:

Citrobacter freundii Enterobacter cloacae Escherichia coli Klebsiella oxytoca Klebsiella pneumoniae

Gram-positive: Enterococcus faecalis Enterococcus faecium

In vitro data are available for the following microorganisms, but clinical significance is unknown:

Citrobacter koseri Klebsiella aerogenes

ETEST® is a thin, inert and non-porous plastic strip carrying on one side the MIC reading scale in ug/mL, and on the other side a predefined antibiotic gradient.

When the strip is applied to an inoculated agar surface, the preformed antibiotic gradient immediately transfers into the agar matrix, then forming a stable, continuous and exponential gradient of antibiotic concentrations directly underneath the strip. Bacterial growth becomes visible during incubation, and a symmetrical inhibition ellipse centered along the strip appears. The MIC value is read from the scale in terms of ug/mL at complete inhibition of bacterial growth, where the pointed end of the ellipse intersects the strip.

ETEST® Eravacycline contains a range of eravacycline from 0.002 to 32 µg/mL.

The document describes the performance of the ETEST Eravacycline (ERV) (0.002-32 ug/mL) device for determining the minimum inhibitory concentration (MIC) of Eravacycline against various microorganisms.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for Antimicrobial Susceptibility Test (AST) Systems are typically defined by regulatory guidance documents, such as the FDA Class II Special Controls Guidance Document and CLSI standards. For this device, the performance is evaluated based on Essential Agreement (EA) and Category Agreement (CA) with a reference method. While explicit numerical acceptance criteria for EA and CA are not directly stated as pass/fail thresholds in the provided text, the document implies that the reported percentages of EA and CA demonstrate "acceptable performance" and "substantially equivalent performance" when compared to the CLSI reference method and predicate device.

2. Sample Size Used for the Test Set and Data Provenance

The test set included both contemporary and stock clinical isolates, as well as challenge strains.

• Enterobacteriaceae (Total N = 552):
  • C. freundii (70 isolates)
  • C. koseri (30 isolates)
  • E. cloacae (72 isolates)
  • E. coli (191 isolates)
  • K. aerogenes (32 isolates)
  • K. oxytoca (43 isolates)
  • K. pneumoniae (104 isolates)
  • The overall categorical very major error rate for Eravacycline was evaluated on 92 Enterobacteriaceae clinical and challenge isolates for non-susceptible results. This suggests that at least 92 isolates were non-susceptible for this specific analysis.
• Enterococci (Total N = 137):
  • E. faecalis (74 isolates)
  • E. faecium (63 isolates)
  • The overall categorical major and very major error rates for Eravacycline were evaluated on 128 isolates (for major errors) and 9 isolates (for very major errors). This implies at least 128 isolates were included for major error evaluation and 9 for very major error evaluation for non-susceptible isolates.

Data Provenance: The document states that "External evaluations were conducted with contemporary and stock clinical isolates, as well as a set of challenge strains." The country of origin of the data is not specified in the provided text, but bioMérieux SA is based in France.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and their Qualifications

The document does not explicitly state the number of experts or their specific qualifications. However, it indicates that the device's performance was compared against the "CLSI M07-A11 January 2018 broth microdilution reference method" and "CLSI M100-S28 January 2018 specifications." This implies that the ground truth was established by laboratory personnel proficient in performing and interpreting these standard reference methods, which are widely accepted in microbiology for antimicrobial susceptibility testing.

4. Adjudication Method for the Test Set

The document does not mention an explicit adjudication method (e.g., 2+1, 3+1, none) for the test set. The ground truth was established by comparison to the CLSI broth microdilution reference method. Any discrepancies or "errors" (e.g., Major Errors, Very Major Errors) are noted, and for some cases (e.g., Klebsiella pneumoniae VME), it mentions that "When tests were repeated in triplicate, all the results were in category agreement," which could be considered a form of internal re-evaluation or confirmation rather than formal adjudication by independent experts.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No multi-reader multi-case (MRMC) comparative effectiveness study is mentioned. The device is a diagnostic test for antimicrobial susceptibility, not an AI-assisted diagnostic tool that directly influences human reader performance.

6. Standalone (Algorithm Only) Performance

Yes, a standalone performance evaluation was conducted. The ETEST® Eravacycline device itself is the "algorithm" in this context, as it's a physical strip with a predefined antibiotic gradient designed to produce a measurable MIC value. Its performance (Essential Agreement, Category Agreement, Reproducibility, Quality Control) was assessed independently by comparing its results directly to the CLSI broth microdilution reference method. No human-in-the-loop interaction for interpretation beyond reading the MIC from the strip itself is implied as part of the evaluated "device performance."

7. Type of Ground Truth Used

The ground truth used was the CLSI M07-A11 January 2018 broth microdilution reference method. This is considered the gold standard for determining minimum inhibitory concentrations (MICs) in microbiology and serves as the primary comparative method for new AST devices. Interpretive categories (susceptible, intermediate, resistant) are typically derived from MIC values based on breakpoints established by CLSI guidelines (e.g., CLSI M100-S28).

8. Sample Size for the Training Set

The document does not provide information about a separate "training set" or its sample size. This type of device (an ETEST strip) is a physical, pre-calibrated product based on a chemical gradient, not a machine learning algorithm that requires a training set in the conventional sense. Its design and manufacturing process would be informed by decades of antimicrobial susceptibility testing principles and prior ETEST product development, rather than a data-driven training phase as seen with AI/ML models.

9. How the Ground Truth for the Training Set Was Established

As no training set is described for this type of device, this question is not applicable. The device's fundamental principle is based on established scientific principles of antibiotic diffusion and bacterial growth inhibition, rather than being "trained" on data.

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