Current dosage regimens of antimicrobials have been determined for treatment without taking antimicrobial resistance into account. Enrofloxacin is commonly used to treat avian pathogenic Escherichia coli (APEC) infections. Hence, the first aim is to investigate the current enrofloxacin resistance prevalence in clinical APEC isolates in Kenya. Through PK/PD modelling the posology of the antimicrobial will be optimized for Kenyan broilers chickens taking the current resistance pattern of APEC towards enrofloxacin into account. This will lead to a reduced development and selection of antimicrobial resistance for this particular pathogen.