The Role of Antibiotics in Inflammatory Bowel Disease

Broad-spectrum antibiotics are the mainstay of therapy for patients with Crohn's disease (CD) who present with localized peritonitis due to a microperforation bacterial overgrowth secondary to chronic strictures. They are essential adjuncts to drainage therapy for CD-associated abscesses and for complicated perineal disease. The lack of well-designed, placebo-controlled trials has led to much skepticism about the efficacy of antibiotics as primary therapy for CD. However, a careful review of the experience with antibiotics, including clinical observations and controlled trials, leads to the conclusion that antibiotics have a role as primary therapy in active uncomplicated CD. The efficacy of their response must be considered in well-defined subsets of patients. Ciprofloxacin and metronidazole, the two most widely studied antibiotics, are effective therapy for patients with active ileocolonic and colonic disease and have been shown to reduce recurrence rates after ileocolonic resection. The benefits of these drugs are less clear for patients with uncomplicated ileal disease. Additionally, ciprofloxacin and metronidazole may also serve as an adjunct to immunomodulator therapy. The role of antimycobacterial therapy in treatment of CD is an attractive alternative, and hopefully this therapy will be further clarified when results of ongoing trials become available. In toxic patients with fulminant ulcerative colitis (UC), with or without megacolon, broad-spectrum antibiotics should be a part of the treatment program. In less severely ill patients requiring hospitalization, antibiotics may be given to cover for the potential of a superimposed infection until the workup for infection, including Clostridium difficile is completed. There may be a subset of patients with severe nontoxic colitis with persistent fever and bandemia after steroid therapy who respond to antibiotics, but to date controlled trials have not shown efficacy in this group. Antibiotics should not be routinely used for mild to moderately ill patients with UC, although a trial of ciprofloxacin is not unreasonable prior to colectomy for otherwise refractory patients. The use of rifaximin in UC requires further evaluation in larger studies.