Search for enteric microbial pathogens in patients with ulcerative colitis.

Microbial pathogens were sought in faeces of patients with active ulcerative colitis and again after 3 months treatment. 64 patients were examined during their first episode of ulcerative colitis and 30 with relapse of chronic disease. At presentation, bacterial pathogens were not found; 1 patient had cryptosporidiosis. In 10 patients treatment appeared to result in some loss of colonisation resistance as evidenced by colonisation with beta-haemolytic streptococci, Staphylococcus aureus, candida and Clostridium difficile. Unidentified cytotoxic activity was present in the faeces of 4 patients at presentation and 2 patients during or after treatment. We conclude that enteric infection is an uncommon finding in patients with active ulcerative colitis.