The goal of this research is to compare alterations of gut microbiota and fecal metabolomics alterations between inflammatory bowel disease patients infected with or without Clostridioides difficile. The main questions it aim to answer are: which bacterial genus or fecal metabolites can discriminate IBD patients infected or more likely to be infected with Clostridioides difficile and their role in the pathogenesis of Clostridioides difficile.

type of study: observational study participant population/health conditions

1. population diagnosed with Ulcerative colitis or Crohn's disease
2. Having diarrhea Participants will be included in this research. If there is a comparison group: Researchers will compare healthy people without IBD or any diarrhea to see if disease or diarrhea would affect the gut microbiota and metabolites.

Inclusion Criteria:

• inpatients diagnosed with ulcerative colitis or Crohn's disease in Renji hospital
• age from 18 to 75 years old

Exclusion Criteria:

• other infection caused diarrhea
• other metabolic diseases or inflammatory diseases
• patients who are not able to send back samples 4-6 weeks after therapy

1. IBD group: inpatients diagnosed with ulcerative colitis or Crohn's disease.
2. IBD+CDI group: IBD patients positive for C.difficile toxin and having diarrhea
3. Health control: people without diarrhea or any other intestinal diseases and negative for C.difficile toxin tests

gut microbiota and metabolites change