Development of the EUCAST disk diffusion antimicrobial susceptibility testing method and its implementation in...

Area of Science:

• Clinical Microbiology
• Antimicrobial Resistance
• Diagnostic Testing

Background:

• The European Committee on Antimicrobial Susceptibility Testing (EUCAST) is a key body for antimicrobial susceptibility testing (AST) standards.
• Accurate AST is crucial for guiding antibiotic therapy and combating antimicrobial resistance.
• Disk diffusion methods offer a practical approach for AST in clinical laboratories.

Purpose of the Study:

• To describe the development of the EUCAST disk diffusion method.
• To establish quality control criteria and guidance for its implementation.
• To correlate disk diffusion zone diameter breakpoints with EUCAST clinical MIC breakpoints.

Main Methods:

• Standardized Mueller-Hinton agar formulations (supplemented for fastidious organisms) were used.
• A standardized inoculum was employed to ensure confluent bacterial growth.
• Incubation was performed for 16-20 hours, followed by zone diameter measurement and interpretation against calibrated breakpoints.

Main Results:

• A validated disk diffusion method with specific quality control criteria has been established.
• Zone diameter breakpoints are directly correlated with EUCAST clinical MIC breakpoints.
• The method is applicable to both non-fastidious and fastidious organisms.

Conclusions:

• The EUCAST disk diffusion method provides a reliable and standardized approach for AST.
• Implementation of this method supports accurate interpretation of antimicrobial susceptibility.
• Regular updates and detailed recommendations are available on the EUCAST website.