The Trajectory of Gastrointestinal Symptom Experience Following Fecal Microbiota Transplant for Recurrent Clostridioides Difficile Infection

INTRODUCTION: Recurrent Clostridioides difficile infection (rCDI) increases the risk of persistent gastrointestinal symptoms after treatment. Although fecal microbiota transplantation (FMT) effectively prevents CDI recurrence after antibiotics, the trajectory of gastrointestinal symptom severity remains poorly characterized. METHODS: We tracked gastrointestinal symptom severity in a prospective, multicenter cohort study of adults with rCDI after treatment with standardized FMT products. Patients who experienced a CDI recurrence during the follow-up period were excluded. The IBS Symptom Severity Scale (IBS-SSS) was used as a measure of symptom severity, not as a diagnostic tool. Patients completed the IBS-SSS at the time of FMT, 1-week, 1-month, and 3-months post-FMT. The primary outcome was the change in IBS-SSS score after treatment. Subgroup analyses were conducted among patients with baseline IBS-SSS ≥175 (moderate/severe symptom severity) and <175 (none/mild symptom severity). Linear mixed-effects models were used to evaluate longitudinal changes and identify clinical predictors of IBS-SSS scores. RESULTS: Among 107 patients included, median IBS-SSS scores decreased from 170 (range: 0 to 440) at baseline to 76 (range: 0 to 390) at week 1 and 54 (0 to 445) at month 3 (P<0.001). In those with baseline IBS-SSS ≥175 (n=51), 64% had none or mild symptom severity at month 3. In those with baseline IBS-SSS <175 (n=53), symptom severity was observed to remain as none or mild at month 3 in all but one patient. CONCLUSION: FMT administered for prevention of rCDI was followed by a rapid (1 wk) and sustained (3 mo) reduction in gastrointestinal symptom scores in patients who did not develop CDI recurrence. These data help characterize the expected early post-FMT symptom trajectory, providing foundational evidence to better inform patient expectations and future interventions for persistent symptoms.