**Study on Preventing C. difficile Infection with AZD5148** This study is testing a new treatment, AZD5148, to stop repeat infections from a germ called *Clostridioides difficile* (C. difficile). This germ can cause severe diarrhea and other health problems. AZD5148 is a monoclonal antibody, meaning it is a special protein made in a lab to help the immune system fight the infection. The study is for people 18 years and older who have had a recent C. difficile infection. About 230 participants will be randomly assigned to get either a dose of AZD5148 or a placebo, which is just a saltwater solution. The medicine can be given as a shot in the muscle or through a vein. Participants will need to visit the study site up to 9 times and keep a diary of their symptoms. **Key Points:** 1. **Participation**: Involves up to 9 visits and keeping a diary. 2. **Treatment**: Single dose of AZD5148 or placebo. 3. **Eligibility**: Must have had a recent C. difficile infection and be on specific antibiotic treatments. Make sure you meet the criteria and understand the commitment before joining the study.