Related Experiment Video
Updated: Oct 21, 2025
11:28
A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically
Published on: September 9, 2015
29.3K
Accuracy of gradient diffusion method for susceptibility testing of dalbavancin and comparators
A G Leroy1, V Lavigne-Quilichini1, P Le Turnier2
1Department of Microbiology, University Hospital of Nantes, Nantes, France.
Expert Review of Anti-Infective Therapy
|September 1, 2021
Summary
Gradient diffusion (GD) is a viable alternative to broth microdilution (BMD) for testing dalbavancin, vancomycin, and teicoplanin susceptibility. Accurate daptomycin MIC determination remains challenging with GD.
Area of Science:
- Clinical Microbiology
- Antimicrobial Susceptibility Testing
- Infectious Diseases
Background:
- Accurate antimicrobial susceptibility testing is crucial for guiding treatment decisions.
- Gradient diffusion (GD) offers a potentially convenient alternative to traditional broth microdilution (BMD).
- Evaluating novel methods for established and newer antibiotics is essential.
Purpose of the Study:
- To compare the performance of GD with BMD for determining Minimum Inhibitory Concentrations (MICs).
- To assess the accuracy of GD for dalbavancin, daptomycin, vancomycin, and teicoplanin against staphylococci and enterococci.
- To identify potential challenges in using GD for specific antibiotics.
Main Methods:
- Retrospective determination of MICs using GD and BMD for 93 clinical isolates.
- BMD served as the gold standard for comparison.
- Calculation of essential agreement (EA) and categorical agreement (CA), with analysis of major (ME) and very major errors (VME).
Main Results:
- High essential and categorical agreement for dalbavancin, vancomycin, and teicoplanin.
- Lower essential agreement for daptomycin, though categorical agreement was perfect.
- Minor discrepancies observed for vancomycin and teicoplanin, with no very major errors for dalbavancin.
Conclusions:
- Gradient diffusion is an acceptable and convenient method for dalbavancin, vancomycin, and teicoplanin MIC determination.
- Achieving accurate daptomycin MICs using GD presents ongoing challenges.
- Further validation may be needed for daptomycin susceptibility testing with GD.
