Oral vancomycin may also decrease the production of TNF-α which has been implicated in T-cell reactivity in PSC patients.50,51 Vaughn et al28 have demonstrated that OV in PSC-IBD patients decreases the production of secondary bile acids and lastly, OV results in fecal microbiome changes that coincide with clinical and biochemical improvement and result in a decrease in Fusobacterium and Haemophilus as well as an increase in Veillonella.42 Here, TNF is linked to inflammatory bowel disease.