Overview
Diagnosis
To diagnose small intestinal bacterial overgrowth, several tests may be used to check for excess bacteria in the small intestine, issues with fat absorption or other factors contributing to symptoms. Breath testing is a common noninvasive option. During this test, hydrogen or methane levels in your breath are measured after you drink a glucose and water mixture. A rapid rise in these gases may suggest bacterial overgrowth, though this test is less specific than other methods.
Small intestine aspirate and fluid culture was once considered a reliable test, but it can lead to inaccurate results due to contamination from bacteria in the mouth. Because of this, experts no longer recommend this method. Your healthcare professional may also recommend blood tests to identify vitamin deficiencies or stool tests to check for fat malabsorption. In some situations, imaging tests such as X-rays, CT scans or MRI may be used to look for structural issues that could contribute to bacterial overgrowth.
Treatment
When possible, treatment for small intestinal bacterial overgrowth begins with addressing the underlying cause. For example, surgery may be needed to correct a loop, stricture or fistula in the intestine. If the underlying issue cannot be reversed, treatment focuses on improving nutrition and reducing bacterial overgrowth.
Antibiotic therapy is often the first step in reducing excess bacteria. Healthcare professionals may begin treatment based on your symptoms and medical history, even if test results are inconclusive. A short course of antibiotics can significantly lower bacterial levels, though the bacteria may return once treatment stops. Some people go long periods without needing additional antibiotics, while others require them more frequently. Switching between different antibiotics may help prevent resistance and reduce side effects, such as diarrhea.
Nutritional support is an important part of managing SIBO, especially for those with significant weight loss or vitamin deficiencies. Treatments may include:
• Nutritional supplements, such as vitamin B-12 injections and oral supplements of vitamins, calcium and iron.
• A lactose-free diet if the small intestine can no longer properly digest lactose. Many people benefit from avoiding most lactose-containing foods or using lactase products to help with digestion. Some individuals may tolerate yogurt because the culture process breaks down lactose.
These approaches can help correct deficiencies, ease digestive symptoms and promote healthy weight gain.
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