"Many results drawn from previous studies of the effect of antibiotic use on emergence, selection and spread of antimicrobial resistance (AMR) have lacked a holistic view combining all aspects into one study. The SATURN project aims to study the impact of antibiotic exposure on AMR with a multidisciplinary approach that bridges molecular, epidemiological, clinical and pharmacological research. Two types of clinical studies will be conducted: First, a randomized trial will be performed to resolve an issue of high controversy (antibiotic cycling vs. mixing). Second, 3 observational studies will be conducted to rigorously study issues surrounding the effect of antibiotic use on AMR that are not easily assessable through randomized trials. These clinical studies will serve as a platform to 2 complementary workpackages (microbiology & pharmacology) that will perform important investigations relevant to this call. The work package focusing on molecular studies will generate new evidence about the changes effected by antibiotic therapy on commensal organisms or opportunistic pathogens in the oropharyngeal, nasal and gastro-intestinal flora and study AMR mechanisms and the dissemination of successful clones of fluoroquinolone-resistant, carbapenem-resistant or extended-spectrum beta-lactamase harboring Gram-negative bacteria, MRSA and fluoroquinolone-resistant viridans streptococci. The purpose of the pharmacodynamic study is to model the relationships between antibiotic exposure and AMR emergence over time for various classes of agents. In summary, the overarching rationale of SATURN is to improve methodological standards and conduct research that will help to better understand the impact of antibiotic use on acquisition, selection and transmission of AMR in different environments, by combining analyses of molecular, individual patient-level and ecologic data. The anticipated results may guide clinical and policy decisions to ultimately reduce the burden of AMR in Europe."