PILGRIM

To determine the differential impact of inappropriate antibacterial prescription compared to adequate or no antibacterial prescription on intestinal microbiota domination by EPE or VRE or infection with C. difficile

• To determine the rate of in-hospital vs. pre-admission intestinal colonization with EPE, VRE, and/or C. difficile
• To determine the rate of in-hospital vs. pre-admission intestinal domination by EPE, VRE, or C. difficile infection
• To determine inter-rater reliability of interdisciplinary AMS specialists rating antibacterial prescription appropriateness
• To identify behavioral determinants and knowledge gaps leading to inappropriate antibacterial prescriptions
• To assess the acceptance rate of AMS Board ratings by the physicians participating in the qualitative study
• To assess correlation of appropriate antibacterial prescription with quality indicators of AMS implementation
• To identify risk factors for colonization, intestinal domination, and infection by EPE, VRE and C. difficile, including comorbidities and drugs known to disrupt the intestinal microbiota, and high-risk bacterial clones prone to dominate the microbiota due to high fitness

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• Age ≥ 18 years
• Planned treatment or high likelihood of any systemic antibacterial treatment except trimethoprim/sulfamethoxazole within the next 10 days for a duration of ≥ 5 days
• Patients able to provide a stool sample before or within 4 hours of receiving first antibiotic dosage
• Written informed consent provided prior to inclusion.

• Patients who have received courses of systemic antibacterials for 7 days or more within the past two months
• Patients having received any antibacterial compound other than trimethoprim/sulfamethoxazole within 14 days prior to study enrolment except first antibiotic dosage within 4 hours prior enrolment
• Patients with diarrhea at enrolment (≥3 unformed bowel movements within 24h)
• Patients with a stoma (jejunostomy, ileostomy, or colostomy) at time of inclusion
• Patients on enteral (tube fed or PEG) or parenteral nutrition
• Patient with any social or logistical condition which in the opinion of the investigator may interfere with the conduct of the study, such as incapacity to well understand, not willing to collaborate, or cannot easily be contacted after discharge
• Patients exclusively treated as outpatients without prior hospital admission
• Patient has previously participated in this study

There will be no invasive measures, incl. no additional blood samples. During the course of the study, stool samples will be collected.