Diverticulosis of the colon is a frequent condition in adults in western countries and a significant number of patients experience clinical symptoms even when the diverticulosis is not complicated by diverticulitis.

Both central and mucosal immunity are altered in Uncomplicated Symptomatic Diverticular Disease (USDD) and Rifaximin ameliorate clinical symptoms and normalize the immunological abnormalities.

The Study Protocol is verify the modifications in the immunological pattern induced by reducing bacteria related activation of immunity by Rifaximin treatment.

Inclusion Criteria:

• male and female
• age 18 or more
• radiologic or endoscopic diagnosis of diverticular disease located in sigma or colon descendent
• Informed consent
• patients willing to participate in to the study

Exclusion Criteria:

• other colon diseases
• Inflammatory Bowel Diseases
• signs or symptoms of inflammation
• consumption of : antibiotics, anti-inflammatory drugs ( FANS and 5-ASA), prebiotics, Proton Pump Inhibitors, corticosteroids, fiber within three months
• pregnancy and breast feeding
• acute diverticulitis characterized by:
• moderate/sever pain in left iliac fossa
• fever > 38°C
• abdominal pain
• haematochezia
• leukocytosis (20% more than the normal range)
• remote acute diverticulitis
• rifaximin hypersensitivity
• neoplastic diseases
• immunodeficiencies
• poor physical conditions
• leaver deficiencies (Child C), kidney (Creatinine>2,2 mg/dl), heart (NYHA 3-4)
• major psychiatric illness
• drugs abuses and alcoholism
• participations in other clinical trials within 4 weeks
• patients unwillingness certificate