Irritable bowel syndrome (IBS) is a condition characterized by episodes of abdominal pain, bloating, diarrhea and constipation. Some patients are more likely to have diarrhea, while some are more likely to experience constipation. Others may have alternating episodes of diarrhea and constipation. IBS is also known as spastic colon, spastic colitis or irritable colon.

According to the American College of Gastroenterology, up to 20 percent of Americans have IBS. The condition is twice as common in women as in men. Symptoms usually first appear in late adolescence/early adulthood.

About 70 percent of patients with IBS have mild disease. Symptoms occur infrequently and only occasionally interfere with daily activities. Twenty-five percent of patients have moderate symptoms. The attacks are more intense and occur more frequently, often interfering with daily activities. Roughly five percent of IBS patients have severe disease, marked by frequent, intense bouts of symptoms. These patients often have great difficulty managing their daily activities due to the severity/frequency of symptoms.

The cause of IBS isn't exactly known. Some researchers theorize the condition is caused by problems with intestinal motility (the speed at which food passes through the digestive tract) and altered pain perception. Certain foods, stress or other illnesses may also trigger symptoms.

Treating IBS

There is no cure for IBS. Some patients get relief by avoiding triggers (like certain foods or stress) and adding fiber to their diets. Patients with constipation may need laxatives. Anticholinergic medications reduce painful bowel spasms. Some patients benefit from antidepressants.

The FDA has approved two specific medications for IBS. Alosetron hydrochloride (Lotronex®) relaxes the colon and slows the passage of waste products through the bowel. The drug must be used very cautiously because it has been linked to severe constipation, decreased blood flow to the colon and a few cases of death. Tegaserod maleate (Zelnorm®) is approved for women with IBS who have constipation as their main symptom.

An Antibiotic for IBS

There aren't any conclusive diagnostic tests for IBS. Doctors usually make a diagnosis after considering the patient's symptoms and performing tests to rule out other causes.

Researchers at Cedars-Sinai Medical Center say one of the possible causes of IBS is an overgrowth of bacteria in the small intestine. These bacteria normally reside in the colon, not the small bowel. When a person with IBS eats, the bacteria in the small intestine compete for the food being digested. As the bacteria breaks down the food, they produce a gas that causes bloating and a feeling of stomach pressure or fullness.

The investigators recently conducted a breath test in patients with gastrointestinal symptoms (those with IBS and those without the condition). The lactulose breath test looks for two types of gases that are produced by bacterial overgrowth: methane and hydrogen. Doctors found IBS patients who tested positive for methane gas were most likely to have constipation as their predominant symptom. Those who tested positive for hydrogen were more likely to have diarrhea as their main symptom.

The researchers then investigated the use of an antibiotic, called Rifaximin (Xifaxan ®), as a potential treatment for IBS. Rifaximin is a little different from other antibiotics. The body does not absorb it, so the active ingredients remain in the small intestine - hopefully killing off the unwanted bacteria. In one study, patients who received Rifaximin for ten days experienced a significant improvement in symptoms. In addition, the results lasted for up to ten weeks after discontinuing the drug.

Investigators say bacteria can eventually grow again in the small intestine. So they are now undertaking a new study to find out if the drug Tegaserod maleate (Zelnorm®) can prevent bacterial overgrowth for longer periods of time.

For general information on irritable bowel syndrome:

American College of Gastroenterology

Irritable Bowel Syndrome Association

National Institute of Diabetes and Digestive and Kidney Diseases Click Here for information about the breath test