Irritable Bowel Syndrome and bacterial overgrowth.

Irritable Bowel Syndrome is a condition that affects more than twenty percent of Americans and is in the top 10 most common chronic medical condition in USA. Sufferers with Irritable Bowel Syndrome have abdominal pain often eased by defaecation. In addition there is associated bloating and altered bowel habits and form. Constipation and/or diarrhoea are common.

At present no one knows the exact cause, no one treatment is effective in a large group of patients and there is no cure. In fact medical treatment has fallen well below patients’ expectation.

Although no one can give you a specific cause for Irritable Bowel Syndrome, there are various suggestions. There is a higher incidence of abuse in IBS patients (Talley et al 1994: 50% of IBS patients reported abuse). In addition at least 20% of severe gastroenteritis (especially bacterial) develops Irritable Bowel Syndrome.

Recently trials on a poorly absorbed antibiotic raises the possibility of another cause. Researchers at Cedars-Sinai Medical Centre, Los Angeles studied Rifaximin and found it to be very effective in controlling symptoms of Irritable Bowel Syndrome. Working on the theory that IBS is caused by bacterial overgrowth, they used Rifaximin, a non-absorbed antibiotic. This drug stays in the gut and is not absorbed into the blood stream.

Mark Pimental, MD at Cedars-Sinai linked bloating to bacterial fermentation by using Lactulose breath test to diagnose Small Intestine bacterial overgrowth (SIBO). This test monitors levels of hydrogen and methane on the breath. These two gases are released following bacterial fermentation. Rifaximin was shown to reduce the bacterial level and significantly reduce Irritable Bowel Syndrome symptoms in these patients.

The Lactulose test plus the significant benefits of Rifaximin suggests that small Intestine bacterial overgrowth may be a causative factor in Irritable Bowel Syndrome.

Leonard Weinstock, MD at Washington University tested 254 Irritable Bowel Syndrome sufferers that met the Rome 11 Criteria by using the Lactulose test and found Small Intestine bacterial overgrowth in 161. The patients tested positive for SIBO showed significant improvement of IBS symptoms following Rifaximin treatment.

It seems that Small Intestinal bacterial overgrowth is a possible cause of Irritable Bowel Syndrome and when recognised by a positive Lactulose breath test, a very effective treatment is Rifaximin.

This gives strength to the argument that Irritable Bowel Syndrome is caused by bad bacteria. More trials are needed. In addition not all patients have a positive Lactulose breath test. It is, however, an exiting and encouraging new avenue to pursue. At present Rifaximin is approved by the FDA for use in traveller’s diarrhoea.