Since the new legislation in 2016, the use of (fluoro)quinolones in livestock farming has fallen enormously, but unexpectedly high levels of fluoroquinolone resistance in E. coli are still found in broiler chicken farms. Within the FLUPOUL project, research is being done into the possible explanations for this. A cross-sectional study on broiler farms examines the extent to which the environment is a source for the spread of FQ resistance in broiler chickens and whether FQ-resistant E. coli strains can already be found in the environment before there are any chicks present at the farm. In addition, the objective is to look at how the dynamics of the spread of FQ resistance progress within a flock of broiler chickens and which factors influence this. Subsequently, a longitudinal study investigates the extent to which FQ resistance is transmitted through the chain from parent farms over the hatcheries to broiler farms. Extensive bacteriological analysis, including the use of Whole Genome Sequencing, looks at the phenotypic and genotypic properties of the bacteria in order to find connections that can explain the high prevalence. In addition, an analysis method is set up to detect (fluoro)quinolone residues in broiler chicken feathers in order to determine to what extent residues of (fluoro)quinolones can be found in broiler chicken and parent animal feathers. To be able to rule out with certainty that no (fluoro) quinolone use underlies the FQ resistance. All these parts of the FLUPOUL project will contribute to a better understanding of the problem and the best (preventive) measures can be sought.