Additional Study Information: This study is examining how oral vancomycin, an antibiotic sometimes used to treat Primary Sclerosing Cholangitis (PSC), affects the bacteria living in the gut (the microbiome). The study is observational, meaning it does not alter medical care or prescribe treatment-participants will continue their usual therapy as decided by their doctors. The study will last about six months per participant and involves three study visits for stool collection and questionnaires, which may be completed in person or remotely. This research may help uncover how gut bacteria influence PSC and lead to better treatment strategies in the future. If you have any questions regarding this study, please contact the Transplant Clinical Research Center (TCRC).