BSAC standardized disc susceptibility testing method (version 10)

Abstract

The BSAC standardized disc susceptibility testing method remains unchanged, but there are considerable changes to the interpretative criteria due to continuing harmonization with the European Committee on Antimicrobial Susceptibility Testing (EUCAST) MIC breakpoints. There are a number of agents for which interpretative criteria have been removed. These MIC and/or zone diameter breakpoints will be published on the BSAC web site as a ‘Legacy’ table; they may be used for research or comparative purposes, but are not recommended for clinical management. Notably, testing of staphylococci for susceptibility to glycopeptides by disc diffusion has been removed because this method has been found to be unreliable, particularly for the detection of low-level resistance; low-level vancomycin resistance in staphylococci is increasingly deemed to be of clinical relevance. The tables for anaerobes have been expanded to include MIC breakpoints that have been determined by EUCAST. There are currently no zone diameter breakpoints for these organisms and an MIC method is recommended if susceptibility testing is required.