Treatment with non-pathogenic Escherichia coli might help to maintain remission in ulcerative colitis. A study published in the Lancet (1999;354:635) has found E coli treatment to be as effective as mesalazine in maintaining remission. The authors comment that the results indicate a link between colonic bacteria and the relapses that occur in ulcerative colitis.
The randomised, double-dummy trial conducted by Dr Biorn Rembacken (centre for digestive diseases, Leeds General Infirmary) was divided into two phases: treatment of active disease, followed by maintenance therapy during remission. While patients had active disease, they were given oral gentamicin (to suppress their own E coli flora) and steroids as enemas or oral preparations. Fifty-nine of these patients then received mesalazine 800mg (400mg when in remission) three times daily and 57 received two enteric coated capsules twice daily (daily in remission) of non-pathogenic E coli. Seventy-five per cent of patients in the mesalazine group and 68 per cent in the E coli group achieved remission. If remission was not achieved by 12 weeks, the patient was withdrawn from the trial. In the one year follow-up period, 73 per cent of patients in the mesalazine group and 67 per cent in the E coli group relapsed.
The authors suggest three possible mechanisms by which non-pathogenic E coli may exert its effect: it may prevent pathogenic bacteria from binding to the intestinal mucosa by blocking receptors; it may produce bacteriocins or microcins that eliminate other enterobacteria; or it may alter the pH or chemical composition of the colon, resulting in unfavourable conditions for pathogenic bacteria. The authors conclude: “The manipulation of the colonic bacteria with antibiotics and probiotic agents may prove more effective and better tolerated than immunosuppressants in the future.”
Dr Rembacken told The Journal on August 25 that ulcerative colitis could be caused by an imbalance in gut flora. The treatment with E coli had a rebalancing effect. He said that he planned further work around the topic, possibly looking at the link between ulcerative colitis and the adhesive properties of E coli.