Study of Antibiotics in the Treatment of Colonic Crohn's Disease

Crohn's disease (CD) is a form of inflammatory bowel disease that can affect any part of the digestive system. Symptoms of this chronic illness include abdominal pain, bloating, nausea, vomiting, and diarrhea. CD also causes bowel wall ulcers, strictures (narrowings of a hollow structure due to scar tissue and swelling), and fistulae (abnormal passages from the intestines to another organ or to the skin). CD is thought to arise from a combination of inherited (genetic) factors and some undefined environmental factor(s). One environmental factor that has been shown to be intimately involved with the development of CD is the presence of bacteria that normally inhabit the intestines. As a result, some physicians have tried to alter the normal bacterial population as a means of controlling the inflammation (swelling) in the intestines of individuals with CD. Among such strategies is the use of a combination of metronidazole and ciprofloxacin. These broad-spectrum antibiotics control CD symptoms by acting on the intestinal bacteria that can contribute to chronic inflammation. More investigation is needed to firmly establish the usefulness of this therapy because previous clinical trials have given mixed results, although they have suggested that antibiotics can be particularly useful in cases of Crohn's colitis (CD that primarily affects the large intestine). Because these earlier studies have lacked a large enough patient population with colonic involvement, a trial focusing on this CD subgroup with a sufficient number of subjects will help to clarify the value of combining metronidazole and ciprofloxacin. The proposed study will test the hypothesis that combination antibiotic therapy is effective in the treatment of CD involving the colon. The study will compare the use of combination therapy consisting of metronidazole and ciprofloxacin with placebo (dummy tablets) and will examine the results of treatment at the end of 8 weeks of treatment.