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Small Intestinal Bacterial Overgrowth


Small Intestinal Bacterial Overgrowth (SIBO) is a condition where the small intestine is populated by an abnormal amount and/or types of bacteria. SIBO can be caused by many gastrointestinal conditions. It can be diagnosed by the lactulose breath test. In this test, a non-absorbable sugar solution is swallowed and hydrogen and methane gases are measured in the breath. Gas levels rise as the sugar solution passes through the intestine resulting from fermentation of the sugar by bacteria. If the gas levels rise quickly and to an abnormal level a diagnosis of small intestinal bacterial overgrowth can be made and treated. The majority of the gas that is produced by bacteria in the small intestine and then most of it is eventually absorbed by the lining and then taken up in the blood stream and then is expelled through the lungs. The effects of SIBO in people include a variety of symptoms including bloating, gas, pain, diarrhea, constipation, irritable bowel syndrome, muscle pain (fibromyalgia), interstitial cystitis, restless leg syndrome, rosacea, and bad breath.

The most common cause of SIBO is the reduction of the normal cycle of muscular activity of the small intestine at night. It is during these muscular contractions that the small intestine is stripped clean and by doing so keeping the bacterial population low. This disorder can result from an insult caused by infection in the past (including traveler’s diarrhea, gastroenteritis, and food poisoning). The effect can last for many years and as a result the normally small population of small intestinal bacteria will grow.

To treat SIBO we like to start with an antibiotic called Xifaxan. This non-absorbable, small intestinal targeting antibiotic is taken as follows: six pills a day for ten to twenty days depending on the severity of the breath test abnormality. A program to help with reimbursement by your insurance is available through Salix Pharmaceuticals (1-866-943-2926). When the insurance company refuses to pay for Xifaxan and the program to help get certification, other antibiotics can be used. These antibiotics (Cipro, Augmentin, Flagyl, and Neomycin) each have their own risks and side effects. Cipro and Augmentin can cause rash and antibiotic associated diarrhea. Flagyl (metronidazole) can cause a temporary metallic taste and nausea; rarely with short term treatment, there can be numbness or tingling in the arms or legs. Neomycin can rarely cause hearing loss or kidney problems when there are pre-existing problems. Neomycin is often prescribed with Xifaxan where there are excess methane-producing bacteria.

After antibiotic treatment is finished and the symptoms improve, then we treat the underlying muscular disturbance with either low dose erythromycin or naltrexone each night at bedtime. Erythromycin is a common antibiotic has properties of a hormone that stimulates small intestinal muscular activity. Medication is often needed as a long term treatment to prevent relapse of SIBO. For those who are allergic to erythromycin, Align probiotic can be taken once nightly to try to help prevent SIBO. Naltrexone is an anti-opioid medication that can stimulate small intestinal activity. In cases where erythromycin, naltrexone, or Align are not effective, then periodic or maintenance doses of Xifaxan may be prescribed. Some individuals may benefit from other medications.

In individuals where we suspect that there has been damage to the lining of the small intestine by SIBO, we will try to help repair this intestinal permeability (also known as “leaky gut”) with 1 month of Zinc 200 milligrams daily and a probiotic capsule (healthy bacteria – examples include Align and Flora-Q). If there is a relapse of the infection with return of the original symptoms, then Xifaxan or other antibiotics will need to be prescribed again.

During the first few days of Xifaxan treatment it is not unusual to have more gas, discomfort and diarrhea. It is important to reduce carbohydrates (bread, pasta, rice, cereal, dairy with lactose and fruit) during this time and continue to take the medication. People who have long standing of irritable bowel syndrome or fibromyalgia and are taking anti-depressants for these conditions will need to continue this therapy for a period of time. If SIBO is effectively treated then these medications can be discontinued under your doctor’s direction.

Restriction of artificial sugars can be helpful as a long-term way to reduce the risk of relapse of SIBO. Omit Splenda, gums with artificial sugar, and prepared foods that contain fructose and fructose corn syrup. Sensitivity to wheat products or the gluten sensitive disease called celiac disease should be considered. Lactose intolerance may be a temporary or a long-term problem for people who have SIBO.