The overall objective of this research is out there to gain more insight into the epidemiology of the introduction, selection and spread of antimicrobial resistance (specifically fluoroquinolone and beta-lactam resistance) when the indicator germ (Escherichia coli) in broilers. Based on these insights will be developed that will allow to better understand the resistance problems and to reduce. To achieve this will be initially developed animal models that allow to study the introduction, selection and spread of antimicrobial resistance in broilers.