Bacterial Overgrowth
John F. Pohl, Christopher Jolley, Daniel Gelfond in Pediatric Gastroenterology, 2014
Small intestine bacterial overgrowth (SIBO) is defined as a condition in which abnormally large numbers of bacteria are resident in the small intestine. SIBO is fairly rare, although its true prevalence and relationship to specific diseases and symptoms, such as irritable bowel syndrome, is in dispute. The proximal small intestine usually contains a small number of culturable bacteria that rarely exceeds 103 colony units (CFU)/ml in the jejunum. In about 33% of healthy individuals no bacteria can be cultured. It is important to note, however, that not all bacteria in the gastrointestinal (GI) tract can be cultured and that the application of molecular techniques to the study of small bowel ecology may change current understanding of SIBO. SIBO most commonly develops after surgery that creates a pouch or partial obstruction (25.1), when the small bowel has abnormal motility, or when the small bowel length is so short so that bacteria can increase substantially in number and even compete for nutrients.
Irritable Bowel Syndrome
Nicole M. Farmer, Andres Victor Ardisson Korat in Cooking for Health and Disease Prevention, 2022
Small intestinal bacterial overgrowth (SIBO) is one of the exciting but still somewhat controversial areas of IBS research. In general, it is thought that the bacteria of the gut microbiome belong, primarily, in the colon (large intestine) with a transition zone in the terminal ileum. For the most part, there shouldn’t be a large population of bacteria in the small intestine. This is because the high acidity of the stomach as well as the effects of digestive enzymes and bile retard the colonization of bacteria introduced to the small intestine via our food and, whatever does make it past these defenses, are swept down to the colon via the migrating motor complex (peristalsis). Finally, an intact ileocecal valve prevents bacteria from moving upwards from the colon to the small intestine. However, when these defenses break down, colonic bacteria can proliferate in the small intestine, and this can often cause problems. This is known as SIBO.
Palliative Care of Gastroparesis
Victor R. Preedy in Handbook of Nutrition and Diet in Palliative Care, 2019
Finally, there has been a correlation between GP and SIBO. In health, peristalsis and normal gastric acid production prevent the colonization of bacteria. It has been shown that an impairment of either would contribute to the colonization of bacteria within the small intestine. Many patients with GP are treated with acid-suppressive medication to reduce reflux symptoms. This resultant hypochlorhydria predisposes this specific subgroup to development of SIBO. Bacterial colonization in the small bowel results in mucosal inflammation, which further results in impaired nutrients absorption (Zaidel and Lin 2003). Patients with SIBO present with symptoms that mimic GP which include gas, bloating, abdominal distension, nausea, diarrhea and decline in nutritional status. It is imperative that patients with GP should be evaluated for concurrent SIBO (Reddymasu and Mccallum 2010). Treatment for SIBO includes a course of antibiotics such as metronidazole, ciprofloxacin, amoxicillin/clavulanate or rifaximin for 7–14 days.
Small intestinal bacterial overgrowth is associated with Diarrhea-predominant irritable bowel syndrome by increasing mainly Prevotella abundance
Published in Scandinavian Journal of Gastroenterology, 2019
Kang-Qi Wu, Wen-Jing Sun, Ning Li, Yu-Qin Chen, Yan-Ling Wei, Dong-Feng Chen
Previous studies have reported that the diversity, stability and metabolic activity of the intestinal microbiota in IBS-D patients differs from healthy population, indicating that some relations may exist between dysbiosis and IBS-D [4]. Small intestinal bacterial overgrowth (SIBO), which is caused by excessive bacteria in the small intestine, is a common type of dysbiosis. Gastrointestinal symptoms of SIBO patients, such as abdominal discomfort, dyspepsia, diarrhea and bloating, were similar as patients with IBS-D [3]. Recent investigations showed that more than one-third of IBS-D patients were SIBO positive [5]. Moreover, the occurrence of SIBO in IBS-D were nearly five-fold than healthy population [5]. These epidemiology data raise the potential relationship between SIBO and IBS-D, whereas how SIBO is associated with IBS-D remains uncertain [6–8]. The aim of the present study is to investigate the relationship between SIBO and IBS-D and relevant reasons.
Methane positive small intestinal bacterial overgrowth in inflammatory bowel disease and irritable bowel syndrome: A systematic review and meta-analysis
Published in Gut Microbes, 2021
Arjun Gandhi, Ayesha Shah, Michael P. Jones, Natasha Koloski, Nicholas J. Talley, Mark Morrison, Gerald Holtmann
There is emerging evidence that microbial dysbiosis, defined as the alterations in the composition, density and function of the intestinal microbes plays an important role in a variety of gastrointestinal and extraintestinal conditions.1, 2 Small intestinal bacterial overgrowth (SIBO), a condition where the overall homeostasis of the small intestine becomes dysregulated through presence of altered number and type of microbes is an example of gut microbial dysbiosis.3 The current gold standard for diagnosing SIBO remains small bowel aspirate and culture, however in clinical practice breath testing has largely replaced culture methods given the simplicity and noninvasive nature of these tests.3 Breath tests are based on the principle that human cells do not produce hydrogen and/or methane gas4 and presence of these gases in the human breath indicates the metabolism of (non-digested) carbohydrates by gut microbes.5
Breathing new life into clinical testing and diagnostics: perspectives on volatile biomarkers from breath
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
Jordan J. Haworth, Charlotte K. Pitcher, Giuseppe Ferrandino, Anthony R. Hobson, Kirk L. Pappan, Jonathan L. D. Lawson
Hydrogen and methane breath tests (HMBTs) are widely used for the diagnosis of SIBO. The development of SIBO is associated with motility disorders, after effects of surgery, structural disease, and stomach acid-suppression (i.e. achlorhydria or use of proton pump inhibitor drugs) [36]. There is no established gold standard investigation for SIBO [37]. Microbial culture of a jejunal aspirate has been used but is invasive, expensive, and not widely performed in clinical practice. In addition, aspirate cultures pose high risks of both false positives, through contamination by oral bacteria or saliva, and false negatives, through irregular distribution of bacteria through the bowel causing aspiration of a non-representative sample or of cultivation-resistant species [38]. Consequently, the use of HMBT for the assessment of SIBO has been widely adopted in clinical practice as a safe and noninvasive alternative.