10.07.2025

SOP 9 updated

SOP 9: Procedure for establishing zone diameterbreakpoints and quality control criteria for newantimicrobial agents, has been updated from 9.3 to 9.4.

This SOP describes the necessary interaction between EUCAST, the EUCAST Development Laboratory (EDL) and when required, pharmaceutical companies to define the correlation between MIC and zone diameters to allow EUCAST to determine zone diameter breakpoints. The SOP also describes how quality control (QC) criteria for new antimicrobial agents are developed. This relates specifically to:

• Evaluation of disks of the selected content (potency)
• Identifying and defining relevant QC strains
• Establishing targets and acceptable ranges for QC strains
• Determining the correlation between MIC values and inhibition zone diameters to define zone diameter breakpoints.