Background: Faecal microbiota transplant (FMT) is an effective treatment for multiply recurrent C. difficile infection (mrCDI). Less is known about rates of reinfection after successful FMT. We aimed to estimate the incidence of CDI reinfection, 6 or more months after FMT, to determine whether rates differ between mrCDI treated with and without FMT and whether proton pump inhibitor (PPI) therapy increases the risk of reinfection. Methods: Among patients with mrCDI (defined as >= 2 recurrences after the initial CDI episode) we compared reinfection with CDI (defined as a first recurrence > 183 days after treatment completion) in patients who underwent antibiotics followed by FMT with those treated with antibiotics alone in Optum's de-identified Clinformatics Data Mart Database (OPTUM CDM). We also compared reinfection between those with and without PPI use in OPTUM CDM and the American Gastroenterological Association FMT Registry. Results: In OPTUM CDM, 6384 patients treated with antibiotics alone and 1786 with antibiotics + FMT met inclusion criteria (median follow-up 704 days). One-year and 3-year CDI reinfection incidences were 5% and 10% in the FMT group and 6% and 12% in the antibiotics group: Cox regression HR 0.89, 95% CI 0.73-1.08. PPI use was associated with an increased risk of reinfection following FMT (HR 1.57, 1.03-2.41) in OPTUM CDM and in the FMT Registry (HR 1.62, 95% CI 0.84-3.12). Conclusions: CDI reinfection rates are low after successful FMT and similar to rates in patients treated with antibiotics alone. PPI use was associated with reinfection, supporting reassessment of the ongoing indication for PPI therapy in patients with mrCDI.
