Pilot Study of Fundamental Modification of the Gut Microbiota in the Treatment of Refractory Crohn's Disease

Investigators will evaluate the efficacy of a novel treatment regimen, employing non-immunosuppressive medications, in the management of refractory CD or IBDU. Refractory patients include those patients who have experienced loss of responsiveness (LOR) or primary nonresponse to an immunomodulator or a biologic. Investigators will treat participants with a combination of gut microbiota-targeted therapies to restore a healthy gut microbiome composition. Investigators believe that this strategy will both treat the gut inflammation associated with inflammatory bowel disease (IBD) as well as salvage response to immune suppressive therapies. Investigators will also evaluate the effect of PEG lavage alone on fecal calprotectin and gut microbiota. Participants in this arm, will be undergoing a PEG lavage in preparation for a endoscopy for clinical care. They will be asked to provide stool samples, prior to and after their PEG lavage. Participants will not be receiving any investigational treatments.