Date: Wed, 13 Dec 2000 21:45:01 -0800

Study links intestinal bacteria to irritable bowel syndrome

December 13, 2000

Web posted at: 11:19 AM EST (1619 GMT)

LOS ANGELES, California (Reuters) -- Irritable bowel syndrome, a chronic condition believed to plague 20 percent of the adult population in developed countries, may be caused by too much bacteria in the small intestine, researchers said Wednesday.

It was the first time a potential cause for the disease has been identified and could lead to a radical shift in treatment, according to the lead investigator in the study.

"This is really exciting because it points to the cause of the disease. Treatments for irritable bowel syndrome (IBS) to this point have been directed at symptoms, not any cause," said Dr. Mark Pimentel, who is also assistant director of the gastrointestinal motility program at Cedars-Sinai Medical Center in Beverly Hills, California.

Symptoms of IBS, which is diagnosed in twice as many women as men, include gas, bloating, abdominal pain, constipation and diarrhea.

"We found that 78 percent of IBS patients have bacterial overgrowth in the small intestine. Antibiotics got rid of the disease in half of the patients that got rid of the overgrowth," Pimentel said.

Treatments for the gastrointestinal condition currently range from anti-depressants, which are supposed to alter nerve endings in the abdomen, to advice to eat more fiber in order to alleviate constipation.

Last month, the IBS drug Lotronex was pulled from the market by its maker Glaxo Wellcome after the U.S. Food and Drug Administration voiced concerns about side effects and said three deaths might have been related to the product.

Lotronex, marketed as a treatment for women with diarrhea-predominant IBS, was linked to reports of a bowel condition called ischemic colitis, which restricts blood flow to the colon. Some Lotronex users also reported severe complications from constipation.

Zelmac, an experimental drug described as a treatment for women with constipation symptoms of IBS, is expected to be approved by the FDA and launched by its maker Novartis AG by the middle of next year.

But Pimentel said pharmaceutical companies may want to redirect their research efforts to target alternatives for eradicating bacteria in the small intestine.

"Once they see this trial, they will really wonder what they're doing," Pimentel said.

Cedars-Sinai investigators evaluated 202 patients who underwent a specialized breath test to determine the presence of small intestinal bacterial overgrowth, a condition in which bacteria typically found in the colon makes its way up into the small intestine.

"The bacteria produces the bowel symptoms. The fact that we found the overgrowth in almost 80 percent of patients with IBS is quite dramatic," Pimental explained.

He noted that there are several mechanisms designed to prevent the build-up of bacteria in the small intestine, but researchers do not know what goes wrong to allow the bacteria to accumulate.

Participants in the study were treated for 10 days with antibiotics, which eliminated signs of the disease in 25 of the 47 patients who returned for follow-up exams. Treatment with alternative antibiotics has been effective in about 90 percent of patients at the Cedars-Sinai clinic, Pimental said.

Of the 25 study patients in which no small intestine bacteria was detected after treatment with antibiotics, 12 reported no symptoms of IBS and 13 reported significantly reduced symptoms, the researchers said.

"We are concerned about overtreatment with antibiotics and potential resistance to antibiotics. We are currently studying other therapies for eliminating the bacteria, but the results so far are not objective," the Cedars-Sinai doctor said.

The Cedars-Sinai team, which published its study results in the December issue of The American Journal of Gastroenterology, is currently conducting a double-blind study comparing treatment with antibiotics to placebo in IBS patients.