Use of Antibiotics to Eradicate Bacterial Pathogens Colonising the Colonic Mucosa in Ulcerative Colitis Patients

It is now widely acknowledged, as a result of experimental studies over the last 30 years, that the mucosal flora of the large bowel are essential to the pathogenesis of ulcerative colitis. Whilst treatment with antibiotics, therefore, might seem a logical approach, a number of clinical trials have proved disappointing. This is because the principal bacteria involved in the inflammatory process have not been identified and their sensitivities to the antibacterials determined. Moreover, we are only now beginning to understand the physiology of biofilm populations on mucosal surfaces, one property of which is antibiotic resistance. Our own studies have show a distinctive bacterial population of the mucosa with UC patients with reduced numbers of protective bifidobacteria and increased enterobacteria which we have linked to disease activity. Antibiotic resistance to commonly used gut antibiotics is widespread in these bacteria.

Our study, therefore, will commence with multiple biopsies of the distal large bowel mucosa being taken in patients with active UC and detailed microbiological characterization of the flora using viable counting, chemotaxonomy and molecular approaches. Antibiotic sensitivities of the likely pathogens will be determined and dissemination of antibiotic resistance genes in the mucosal microbiota followed using real time PCR. Markers of mucosal immune response including proinflammatory cytokines and human betea defensins will also be measured. Two weeks after initial biopsies, the patient will return to pur research IBD clinic where the appropriate combination of antibiotics will be prescribed and these will be taken for one month. A further assessment will occur at the end of this period including mucosal biopsies. endpoints will include clinical activity index, bowel habit diaries, sigmoidoscopy score, mucosal immune markers and routine haematology and biochemical indices. Because of the long term effect of antibiotics on the gut mucosa, which can last for many months, the study cannot be randomised and therefore, the run in period will be taken as a control period and the four weeks on the antibiotic will follow in all patients. The prime endpoint will be sigmoidoscopy score and the subjects will be followed up for a further six months after the study to look for long term benefits.