Treatment of functional bowel disorders: is there room for antibiotics?

Small bowel bacterial overgrowth is a syndrome associated with a broad range of predisposing conditions, characterized by the presence of pathological amounts or types of bacteria at the level of the small bowel, clinically evident with a spectrum of symptoms such as diarrhea, flatulence, abdominal pain and bloating. Some of these symptoms are very common complaints in patients suffering from functional bowel disorders (FBDs). Although the pathophysiological mechanisms responsible for FBDs are certainly multifactorial and not yet completely understood, several pieces of evidence suggest that an increased metabolic activity of intestinal bacteria is responsible for gas-related intestinal symptoms in a large subgroup of patients. In addition, byproducts of colonic fermentation might be able to trigger symptoms in those patients displaying visceral hypersensitivity. Targeting enteric bacteria with antibiotics therefore represents a logical approach to FBDs. Although systemic antimicrobials have been mostly used in the past, the availability of poorly absorbed antibiotics like rifaximin, being safe and effective, has represented a step forward in the treatment of this challenging clinical condition.