Advanced Metagenomic Analysis of Human Colonic Microbiota in Patients With Chronic GI Disorders

Inclusion Criteria:

IBS: 50 consecutive patients presenting to KFMC GI service after launching the project on July 2010, will be recruited if they meet the following conditions:

1. Meet the diagnostic criteria as per ROME-II classification and as judged by experienced consultants for not less than 5 years.
2. IBS with diarrhea or constipation or mixed predominance pattern will be included.
3. Standard diagnostic tests have to be done to exclude any possible organic lesion to explain the abdominal pain, and all have to be negative.

IBD: from the KFMC GI service database, 50 Ulcerative Colitis (UC) and 50 Crohn's Disease (CD) will be selected according to following:

1. Confirmed diagnosis as CD or UC based on clinical, endoscopic and histological criteria.
2. Specifically did not use antibiotics for last 6 months before enrollment.
3. Detailed information about current treatment regimen has to be provided, and current use of 5-ASA, Steroid or Azathioprine will not hold from enrolling the patients as we cannot have patients off any one or more of these medications. (Obviously, we cannot exclude effects of these medications on microbiota, but it is not the focus of the current study).
4. None of the patients selected would be on anti-TNF medications.

CRC: 50 consecutive cases of confirmed CRC as per histological diagnosis made by 2 experienced pathologists will be included. Feasibility to do full colonoscopy before any surgical resection would be a condition to recruit any patient.

Normal Subjects: 50 normal control groups that are matched for age and sex to the other 3 disease groups will be selected from consecutive CRC screening colonoscopy subjects who get referred to KFMC GI service during the study period, and proved to have no GI disorders. 25 will be selected from Urban and 25 from Rural areas of KSA.

Exclusion Criteria:

1. Treatment with antibiotics for the last 6 months before enrollment.
2. Absence of recent infective colitis, bowel obstruction, or colonic/small intestinal resection surgery.
3. Not on any medication that may affect gut microbiota, like: cholestyramine, ursodeoxycholic acid, gut prokinetic agents.
4. Refusal to comply with the unified bowel preparation instructions for all cases.