Edupath Newsletter April 2019 – ADVANCES IN MEDICAL MICROBIOLOGY: NEW DEFINITIONS OF SUSCEPTIBILITY TESTING CATEGORIES S, I AND R
The European Committee on Antimicrobial Susceptibility Testing (EUCAST) has redefined the antimicrobial
susceptibility testing categories S, I and R. Traditionally these are defined as S = susceptible, I = intermediate and R =
resistant. However, these definitions do not adequately take into account the pharmacokinetic (Pk) and
pharmacodynamic (Pd) aspects of antimicrobial usage. Dose optimization of antimicrobials is currently considered of
paramount importance in successful treatment of infectious diseases, and this is achieved through targeting the
optimal Pk-Pd parameter associated with each antimicrobial agent.