E.coli Nissle 1917 (Mutaflor®) is equivalent to mesalazine in preventing disease relapse in ulcerative colitis. However, data on ability of E.coli Nissle 1917 (Mutaflor®) to induce remission compared with placebo is limited. Investigators aim to investigate the efficacy of E.coli Nissle 1917 (Mutaflor®) as an add-on treatment to 5-ASA in mild to moderate ulcerative colitis.

This is a multicentre, double-blind, randomised, placebo-controlled study in patients with mild-to-moderate UC.

Subjects were randomly assigned to receive either E.coli Nissle 1917 (Mutaflor®) or placebo once daily for 8 weeks, and inflammatory bowel disease questionnaire (IBDQ) scores, clinical remission, and response rate were compared.

Inclusion Criteria:

• Ulcerative colitis patients over the age of 19 with mild to moderate symptoms using 5-ASA (Mayo score 3-9)
• Patient who signed the consent form

Exclusion Criteria:

• The extent of ulcerative colitis is limited to proctitis
• History of bowel resection
• History of using other medication than 5-ASA such as immunomodulators, steroid or biologics within 3months
• history of using antibiotics or probiotics within 2 weeks
• Pregnant or lactating woman
• Requiring hospitalization and imminent need for surgery