Support of Colonization Resistance of the Gut Microbiota with the Synbiotic Food Supplement Nagasin®

Inclusion Criteria: * C. difficile infection (CDI) diagnosis * antimicrobial treatment (e.g. metronidazole, vancomycin or fidaxomicin) for C. difficile infection at ICF * Written informed consent by the participant after information about the research project Exclusion Criteria: * total parenteral nutrition * insulin-dependent (type 1) diabetes * severe disease defined as any of the following: * White blood cell count (WBC) \> 30,000 or \< 1000 cells/mm3 * Neutropenia \< 500 x 10\^9 per liter * Intensive care unit (ICU) patient at time C. difficile infection diagnosed * In case no hematology values are available, presence of severe can be evaluated by the local principal investigator or his designee * is severely immunocompromised as defined by any of the following: * active malignancy receiving severe immunosuppressive chemotherapy with subsequent leukopenia (as defined above) * long-term systemic steroid therapy ≥ 30 mg / d * recipients of stem cell transfer (≤ 12 months) * severe inborn immune deficiency or severe immunosuppressive therapy as evaluated by the investigator * HIV patients with low CD4+ cell count (\< 200 x 10\^9 per liter) * Inflammatory bowel disease patients if: * severe ulcerative colitis (classified as endoscopic Mayo = 3 (max. 30 days old) or as evaluated by investigator) * Severe Crohn's disease with acute penetrating complication (abscess and/or actively draining fistulae) or as evaluated by investigator * Liver cirrhosis (classified as Child C) with clinically significant portal hypertension and/or low thrombocyte count (20 × 10\^9 per liter) * Acute pancreatitis * prosthetic heart valves or endocarditis * consumption of other high-dose (\>10\^10 cfu/dose) probiotic products during the study period. * Inability to understand and follow study procedures * prosthetic heart valves or endocarditis * consumption of other high-dose (\>10\^10 cfu/dose) probiotic products during the study period. * Inability to understand and follow study procedures