This study explores recurrence of **C. Difficile infections (CDI)**, a bacterial infection causing diarrhea and more serious intestinal conditions, after standard antibiotic treatments. **C. Difficile** bacteria can produce toxins like **Toxin A and B**, which are harmful substances causing symptoms. Researchers aim to see how often the infection returns within **8 weeks** after treatment, and whether these toxin levels can predict recurrence. Participants will need to: - Be adults aged **18-75** with a history of CDI recurrence. - Have completed a recent antibiotic treatment and be symptom-free when starting the study. - Provide stool samples and attend **4 clinic visits** over about **9 weeks**; some visits can be by phone. **Key Points:** - Participants must have a documented CDI recurrence and completed treatment. - The study involves providing stool samples and attending multiple visits. - Individuals with certain health conditions or recently involved in other studies are excluded. This study helps in understanding how to better predict and prevent CDI recurrences, potentially improving treatment strategies. Participants will be screened for eligibility before enrolling.