To Your Good Health: Overgrown small intestine bacteria unresponsive to treatment

BY KEITH ROACH, M.D.

DEAR DR. ROACH: I have been suffering with small intestine bacterial overgrowth syndrome for five years. It started when I was treated for H. pylori with omeprazole. I’ve had two endoscopies, a colonoscopy and lab tests. I’m negative for celiac disease. I had a positive breath test four years ago. I’ve taken five courses of antibiotics, including rifaximin and neomycin with brief relief each time. I’ve followed gluten free and low FODMAP diets and tried several acupuncture sessions to no avail. I’m now taking “herbal antibiotics” without any relief so far. I have well-controlled diabetes.

There does not seem to be consistent or reliable information or treatment recommendations other than antibiotics and diet. Can you guide me toward reliable literature? Do you have any advice for this ailment? I worry about long-term effects like malnutrition and emaciation. — D.D.

ANSWER: Small intestine bacterial overgrowth syndrome is when there are more bacteria in the small intestine than normal. It is uncommon but not rare, although its exact prevalence is unknown. The major symptoms are bloating, gas, abdominal discomfort and diarrhea. It can be complicated by weight loss and vitamin deficiencies.

The diagnosis is made by a breath test, and this ideally looks at both methane and hydrogen in the breath after consuming a test meal of sugar. Whether the breath test result is methane-predominant or hydrogen-predominant affects the likelihood of success of treatment.

The first thing to consider after making the diagnosis is why the SIBO is there. The small bowel has a “transit” time of intestinal contents fast enough that the bacteria normally present in the colon do not have time to go up into the small bowel. Conditions that slow the small intestine, including irritable bowel syndrome, opiate drugs and diabetes affecting the gut all can predispose a person to SIBO, and treatment will not be effective if the underlying cause isn’t attended to. Omeprazole and other proton pump inhibitors prevent the stomach from making acid: Without acid to kill bacteria, SIBO can occur, so these drugs need to be stopped in a person with SIBO. Celiac disease is associated with SIBO and is often undiagnosed.

In hydrogen-predominant SIBO, rifaximin for two weeks usually is effective; however, in methane-predominant SIBO, a combination of rifaximin and neomycin will be more effective. Both regimens are usually two weeks long. In people who fail appropriate antibiotics, many experts recommend an “elemental” diet, which is expensive and not particularly appetizing, for up to three weeks. This diet contains the nutrients, such as amino acids and sugars, already broken down, allowing for faster transit time.

It is probably more effective than a low FODMAPS diet (a diet that restricts certain carbohydrates). That is an effective treatment for some people with irritable bowel syndrome, even if it didn’t work for you. Medication to improve how fast the small intestine squeezes may be helpful, especially in someone with diabetes. Erythromycin is one choice. Its effect of speeding up the gut is more important than its antibiotic effects. Probiotics often are recommended, but there is not good evidence to support their use. I doubt the effectiveness of herbal antibiotics (I’m not even sure what these are) or acupuncture for this condition.

If all of these fail, it’s time to re-evaluate whether the diagnosis was correct (another breath test is probably appropriate), and think about alternative possibilities for the symptoms.

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