Overgrowth free beta
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Gastric acid plays an important role in the regulation of microbiota in the stomach, and diminished acid production (hypochlorhydria), as seen with proton pump inhibitor use and after gastric bypass, has been implicated in development of SIBO. SIBO secondary to adjacent stomach and colon pathologies has been well described.
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SIBO develops when a disturbance occurs which increases the number of small bowel bacteria or alters the population of its microbiota. The ileum has an increased density of bacteria and contains a higher concentration of anaerobes, likely refluxing from the strictly anaerobic environment of the colon. 5 Although an individual's diet and environment can influence the composition, the gut microbiota of the duodenum and jejunum are primarily gram-positive aerobic bacteria with sparse anaerobes. In the small intestine of healthy individuals, there are estimated to be approximately 10 3–10 4 colony-forming units per milliliter (CFUs/mL) of bacteria. Along the GI tract, the concentration of bacteria increases from the mouth to the site of highest bacterial proliferation in the large intestine. In this review, we examine the relationship between SIBO and cirrhosis and what is known about its clinical, prognostic, and therapeutic implications.Ī discussion of SIBO requires an understanding of the gut microbiota and the mechanisms regulating them. 3, 4 Despite the high prevalence of gut flora derangement in cirrhotic patients, the role of SIBO in the pathogenesis of cirrhosis and its complications remains uncertain. In some studies, SIBO has been identified in as many as two-thirds of patients with cirrhosis. 2 Since then, investigators have sought to characterize the prevalence and impact of SIBO in patients with cirrhosis. The association between SIBO and cirrhosis was first reported in 1957, when increased Streptococcus faecalis was found in the small intestine of cirrhotic patients compared with normal subjects. 1 While SIBO has traditionally been considered a malabsorptive disorder associated with gut dysmotility, it has more recently been associated with many clinical conditions, including cirrhosis.
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SIBO is characterized by the presence of excessive density and/or abnormal composition of microbiota in the small bowel. Small intestinal bacterial overgrowth (SIBO) is a pathology of gut microbiota dysregulation. In healthy hosts, microorganisms are present throughout the GI tract and are essential for gut barrier function, digestive support, and immune homeostasis. The bacterial environment of the gastrointestinal (GI) tract has long been investigated for its role in health maintenance and relationship to various disease states. This review will discuss the risk factors, diagnosis, manifestations in cirrhosis, and treatment options of SIBO. However, prokinetics, probiotics, nonselective beta-blockers, and treatment of underlying liver-related pathophysiology with transjugular intrahepatic portosystemic shunt placement or liver transplantation are also being investigated. Antibiotics, especially rifaximin, are the best studied and most effective treatment options for SIBO. As a result, SIBO is implicated as a significant risk factor in the pathogenesis of both spontaneous bacterial peritonitis and hepatic encephalopathy in cirrhotics. Increased intestinal permeability in these patients predisposes to bacterial translocation into the systemic circulation. In cirrhotic patients, the presence of SIBO can lead to profound clinical consequences. Diagnosis of SIBO is performed by breath testing or jejunal aspiration, the gold standard. Additional risk factors for SIBO commonly encountered in cirrhotic patients include coexisting diabetes, autonomic neuropathy, and/or alcoholic use. SIBO is often encountered in patients with cirrhosis as a result of impaired intestinal motility and delayed transit time, both of which are exacerbated by more severe liver disease. Small intestinal bacterial overgrowth (SIBO) is defined by increased density and/or abnormal composition of microbiota in the small bowel.