NEW ORLEANS – Both probiotics and antibiotics can be considered legitimate, evidence-based treatments for irritable bowel syndrome.
The gut flora of patients with irritable bowel syndrome (IBS) differs both quantitatively and qualitatively from that of unaffected individuals. The proposed mechanism of the demonstrated benefit for probiotics and antibiotics lies in the controversial notion that bacterial overgrowth in the small intestines may account for some cases of IBS.
Dr. Patrick E. Young
"The thought is that if you can restore a balanced intestinal flora in somebody with IBS, you may be able to eliminate the symptoms. So a better biome may mean a better life," explained Cmdr. Patrick E. Young, USN, a gastroenterologist at Walter Reed National Military Medical Center in Bethesda, Md.
By far the best-studied probiotic in the treatment of IBS is Bifidobacterium infantis. It is supported by "very powerful" data showing reductions in bloating, abdominal pain, and passing of gas, as well as easing of bowel movement difficulty and normalization of aberrant peripheral cytokine levels, according to Dr. Young.
The effective dose as demonstrated in a 362-patient, multicenter, randomized trial is 1 × 108 CFU/mL (Am. J. Gastroenterol. 2006;101:1581-90). Bifidobacterium infantis is commercially available as a nutritional supplement in fortified yogurt or in capsule form. Long-term efficacy data are lacking, but the probiotic is devoid of significant side effects, the gastroenterologist said.
He noted that a recent meta-analysis concluded that oral rifaximin (Xifaxan) provides significant short-term relief of bloating as well as improved global quality of life scores in patients with IBS. The meta-analysis included five randomized, placebo-controlled clinical trials with a total of 1,803 patients. The number needed to treat was roughly 10 for both outcomes. The outcomes were better in older female patients.
The investigators characterized the 10% therapeutic gain over placebo as "modest" and similar to that provided by other accepted therapies for IBS (Am. J. Gastroenterol. 2012;107:28-35).
To this Dr. Young added his own caveat: The longest study of rifaximin followed patients for only 12 weeks.
"I would caution you in using antibiotics for a benign, incurable condition in general. These typically 20- to 30-year-old patients are going to live for another 40-50 years with the consequences of repetitive antibiotic exposure. This is a relatively new agent, and we don’t know what the long-term effect is going to be. That being said, there have been cases where I have used this with some success," Dr. Young said.
The standard dosing is 550 mg TID for 14 days, he said.
Dr. Young reported having no financial conflicts.