to the editor: I read the article on the treatment of irritable bowel syndrome (IBS) by Drs. Hadley and Gaarder with great interest.¹ Although the information was extensive and well referenced, it missed an important facet of the current understanding and treatment of IBS. The incidence of postinfectious inflammatory bowel disease (7 to 34 percent) has been well studied since the mid-1990s. These patients and patients with long-standing IBS show evidence of a motility disturbance of the nocturnal housekeeper stripping wave of the small intestine with subsequent overgrowth of the innate small intestinal bacteria.² Therefore, a new approach to the treatment of IBS is being applied by gastroenterologists.

Small intestinal bacterial overgrowth (SIBO) is indicated by a positive lactulose breath test in 10 to 85 percent of patients with IBS. Disruption of the normal small bowel bacterial population appears to result in symptoms of gas, bloating, flatulence, and altered bowel function, often in response to food intake. Several randomized, double-blind, and open-label studies have demonstrated the potential benefit of antibiotics, including the nonabsorbed antibiotic rifaximin (Xifaxan) for the treatment of SIBO in patients with IBS and functional bowel syndrome.^3–6 Furthermore, antibiotics are the only pharmacotherapy identified to date to confer sustained clinical benefit beyond cessation of therapy in a randomized, double-blind, placebo-controlled clinical trial of patients with IBS.⁴ The potential benefits of nonabsorbed antibiotics in the management of IBS should be considered.

editor's note: This letter was sent to the authors of “Treatment of Irritable Bowel Syndrome,” who declined to reply.