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Small intestinal bacterial overgrowth (SIBO), also termed bacterial overgrowth, or small bowel bacterial overgrowth syndrome (SBBOS), is a disorder of excessive bacterial growth in the small intestine. Unlike the colon (or large bowel), which is rich with bacteria, the small bowel usually has fewer than 10,000 organisms per millilitre. Patients with bacterial overgrowth typically develop symptoms including nausea, bloating, vomiting, diarrhea, malnutrition, weight loss and malabsorption which is caused by a number of mechanisms. The diagnosis of bacterial overgrowth is made by a number of techniques, with the gold standard diagnosis being an aspirate from the jejunum that grows in excess of 105 bacteria per millilitre. Risk factors for the development of bacterial overgrowth include dysmotility, anatomical disturbances in the bowel, including fistulae, diverticula and blind loops created after surgery, and resection of the ileo-cecal valve, gastroenteritis induced alterations to the small intestine as well as the use of certain medications, including proton pump inhibitors. Small bowel bacterial overgrowth syndrome is treated with an elemental diet or else antibiotics, which may be given in a cyclic fashion to prevent tolerance to the antibiotics sometimes followed by prokinetic drugs to prevent recurrence if dysmotility is a suspected cause. ==Signs and symptoms== Bacterial overgrowth can cause a variety of symptoms, many of which are also found in other conditions, making the diagnosis challenging at times.〔 Many of the symptoms are due to malabsorption of nutrients due to the effects of bacteria which either metabolize nutrients or cause inflammation of the small bowel, impairing absorption. The symptoms of bacterial overgrowth include nausea, flatus, constipation, bloating, abdominal distension, abdominal pain or discomfort, diarrhea, fatigue, and weakness. SIBO also causes an increased permeability of the small intestine.〔 Some patients may lose weight. Children with bacterial overgrowth may develop malnutrition and have difficulty attaining proper growth. Steatorrhea, a sticky type of diarrhea where fats are not properly absorbed and spill into the stool, may also occur.〔 Patients with bacterial overgrowth that is longstanding can develop complications of their illness as a result of malabsorption of nutrients. Anemia may occur from a variety of mechanisms, as many of the nutrients involved in production of red blood cells are absorbed in the affected small bowel. Iron is absorbed in the more proximal parts of the small bowel, the duodenum and jejunum, and patients with malabsorption of iron can develop a microcytic anemia, with small red blood cells. Vitamin B12 is absorbed in the last part of the small bowel, the ileum, and patients who malabsorb vitamin B12 can develop a megaloblastic anemia with large red blood cells.〔 In older adults, small bowel bacterial overgrowth is associated with a higher frequency of diarrhea, a lower body mass index, and a significantly lower serum albumin concentration. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Small intestinal bacterial overgrowth」の詳細全文を読む スポンサード リンク
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