The National Institutes of Health describe irritable bowel syndrome, or IBS, as group of symptoms such as abdominal pain, cramping, bloating, gas, diarrhea and/or constipation caused by abnormal bowel function. Doctors call IBS a syndrome rather than a disease because it occurs in the absence of identifiable anatomic or metabolic abnormalities. Recently, antibiotics have emerged as drugs of interest in the treatment of IBS.
Therapeutic Rationale
In a 2010 report published in the Journal of Gastroenterology and Hepatology, Drs. Uday C. Ghoshal, Hyojin Park and Kok-Ann Gwee explain how interest in antibiotic treatment for IBS evolved from the finding that some people with the disorder have unusually high levels of bacteria living in their intestines. In addition, other people with apparently normal levels of bacteria develop the disorder after gastrointestinal infections.
Evaluation
According to the American College of Gastroenterology, antibiotics work best in people who suffer from diarrhea-predominant IBS. For constipation-predominant IBS, a doctor may order stool cultures or lactulose breath testing first, in order to determine whether antibiotics are likely to be effective.
Drugs of Choice
According to Dr. Mark Pimentel in the June 2010 edition of the American Journal of Gastroenterology, rifaximin represents the agent of choice for people with diarrhea-predominant IBS and people with constipation-predominant IBS who demonstrate normal lactulose breath test results. People with constipation-predominant IBS who show high levels of methane production on lactulose breath tests experience better results with a combination of rifaximin and neomycin, sometimes followed by maintenance therapy with nocturnal erythromycin.
Dosing and Administration
Patients take rifaximin and/or neomycin by mouth three to four times per day, for a period of seven to 10 days. Afterward, some patients begin a single bedtime dose of oral erythromycin for six months or more.
Effectiveness
According to Pimentel, 70 percent of patients with IBS who take antibiotics experience significant symptom improvement. However, in many cases, symptoms recur within a few months or weeks, requiring retreatment. For patients with constipation-predominant IBS and initial abnormal lactulose breath test results, maintenance therapy with erythromycin offers more durable results--lasting six months or more.
References
- National Institutes of Health: What I Need to Know About Irritable Bowel Syndrome
- "Journal of Gastroenterology and Hepatology;" Bugs and Irritable Bowel Syndrome: The Good, the Bad and the Ugly; U.C. Ghoshal, H. Park, K.-A. Gwee; 2010
- American College of Gastroenterology: Understanding Irritable Bowel Syndrome
