After surgery involving the stomach and duodenum (most commonly with Billroth II antrectomy), a blind loop may be formed, leading to stasis of flow of intestinal contents. This can cause overgrowth, and is termed blind loop syndrome.Systemic or metabolic disorders may lead to conditions allowing bacterial overgrowth as well. For example, diabetes can cause intestinal neuropathy, pancreatitis leading to pancreatic insufficiency can impair digestive enzyme production, and bile may be affected as part of cirrhosis of the liver. Proton pump inhibitors, a class of medication that are used to reduce stomach acid, is associated with an increased risk of developing SIBO.Finally, abnormal connections between the bacteria-rich colon and the small bowel can increase the bacterial load in the small bowel. Patients with Crohns disease or other diseases of the ileum may require surgery that removes the ileocecal valve connecting the small and large bowel; this leads to an increased reflux of bacteria into the small bowel. After bariatric surgery for obesity, connections between the stomach and the ileum can be formed, which may increase bacterial load in the small bowel. Diagnosis
The diagnosis of bacterial overgrowth can be made by physicians in various ways. Malabsorption can be detected by a test called the D-xylose absorption test. Xylose is a sugar that does not require enzymes to be digested.
Although irritable bowel syndrome has been shown to respond to the treatment of poorly-absorbed antibiotics, there is limited evidence on the effectiveness of such treatment in cases of SIBO, and as of 2020, randomized controlled trials are still needed to further confirm the eradicating effect of such treatment in SIBO. A course of one week of antibiotics is usually sufficient to treat the condition. However, if the condition recurs, antibiotics can be given in a cyclical fashion in order to prevent tolerance. For example, antibiotics may be given for a week, followed by three weeks off antibiotics, followed by another week of treatment. Alternatively, the choice of antibiotic used can be cycled. There is still limited data to guide the clinician in developing antibiotic strategies for SIBO. Therapy remains, for the most part, empiric. However, concerns exist about the potential risks of long-term broad-spectrum antibiotic therapy.Probiotics are bacterial preparations that alter the bacterial flora in the bowel to cause a beneficial effect. Animal research has demonstrated that probiotics have barrier enhancing, antibacterial, immune modulating and anti-inflammatory effects which may have a positive effect in the management of SIBO in humans. Lactobacillus casei has been found to be effective in improving breath hydrogen scores after 6 weeks of treatment presumably by suppressing levels of a small intestinal bacterial overgrowth of fermenting bacteria. The multi-strain preparation VSL#3 was found to be effective in suppressing SIBO. Lactobacillus plantarum, Lactobacillus acidophilus, and Lactobacillus casei have all demonstrated effectiveness in the treatment and management of SIBO.