Long-Term Outcomes After CDI: FMT Versus Antibiotic-Only Treatment

The goal of this observational study is to learn about the long-term effects of fecal microbiota transplantation (FMT) compared with antibiotic-only treatment in adults who were treated for Clostridioides difficile infection (CDI) at Umeå University Hospital between 2016 and 2024. The main questions it aims to answer are:

* Do patients treated with FMT maintain higher gut bacterial diversity up to 10 years after CDI compared with patients treated with antibiotics only? * Do donor gut bacteria introduced by FMT persist long-term in the recipient's gut? * Are there differences in gut metabolism, gut barrier function, and systemic inflammation between FMT-treated and antibiotic-only treated patients at long-term follow-up? * What are the long-term safety outcomes - including new diseases, hospitalizations, and mortality - in FMT-treated versus antibiotic-only treated patients?

Researchers will compare patients who received FMT to patients who received antibiotics only to see if FMT leads to lasting differences in gut microbiota, metabolism, immune markers, and clinical outcomes.

Participants will:

* Attend a single study visit at Umeå University Hospital * Provide samples of blood, stool, urine, and a nasal swab * Complete two quality-of-life questionnaires

Clinical data will be collected from medical records for all participants.