Small Intestinal Bacterial Overgrowth: Diagnosis, Pathophysiology and Treatment Methods

Small intestinal bacterial overgrowth (SIBO) is the excessive abundance of nonpatogenic microbes in the small bowel, which are characteristic to the large intestine. It is often referred to as dysbiosis. Typical symptoms include: immoderate flatulence, abdominal pain, steatorrhea or micronutrient deficiencies that may cause conditions like anemia or general fatigue associated with it. The dysfunction of the intestinal mucosal barrier and chronic inflammation, caused by SIBO, are the causes of many diseases, for example fatty liver disease and autoimmune diseases, which also act as predispositions to bacterial overgrowth. The diagnosis is based mainly on the breathing tests. The therapy is comprehensive and relies on pharmacological treatment, adequate diet (usually low-FODMAP diet is recommended) as well as preventive measures in order to avoid the relapse. The key to complete recovery is correct identification of the core cause and its removal, which is often not so clear as SIBO manifests itself with many nonspecific symptoms and therefore, may be misidentified as irritable bowel syndrome, celiac disease or other GI tract diseases.

This article reviews and summarizes the current state of knowledge about the bacterial overgrowth in the small intestine.