The gut microbiota is considered to constitute a microbial organ which has pivotal roles in the intestinal diseases and body's metabolism. Evidence from animal and human studies strongly supports the link between intestinal bacteria and inflammatory bowel diseases (IBD). Dozens of studies reported its efficacy in treatment of severe Clostridium difficile colitis. Preliminary studies using fecal microbiota transplantation (FMT) for Ulcerative Colitis (UC), Crohn's diseases (CD), irritable bowel syndrome (IBS) and constipation have also met with some success. However, the results on CD is very limited. This marks the initial step in exploring the potential efficacy of fecal bacteriotherapy for CD. The investigators aim to evaluate the effectiveness, durability, and safety of FMT in a cohort of at least 500 patients with CD over a ten-year period