Prevalence of small intestinal bacterial overgrowth in children with irritable bowel syndrome: a case-control study

Small intestinal bacterial overgrowth syndrome

Human intestinal microbiota create a complex polymicrobial ecology. This is characterised by its high population density, wide diversity and complexity of interaction. Any dysbalance of this complex intestinal microbiome, both qualitative and quantitative, might have serious health consequence for a macro-organism, including small intestinal bacterial overgrowth syndrome (SIBO). SIBO is defined as an increase in the number and/or alteration in the type of bacteria in the upper gastrointestinal tract. There are several endogenous defence mechanisms for preventing bacterial overgrowth: gastric acid secretion, intestinal motility, intact ileo-caecal valve, immunoglobulins within intestinal secretion and bacteriostatic properties of pancreatic and biliary secretion. Aetiology of SIBO is usually complex, associated with disorders of protective antibacterial mechanisms (e.g. achlorhydria, pancreatic exocrine insufficiency, immunodeficiency syndromes), anatomical abnormalities (e.g. small intestinal obstruction, diverticula, fistulae, surgical blind loop, previous ileo-caecal resections) and/or motility disorders (e.g. scleroderma, autonomic neuropathy in diabetes mellitus, post-radiation enteropathy, small intestinal pseudo-obstruction). In some patients more than one factor may be involved. Symptoms related to SIBO are bloating, diarrhoea, malabsorption, weight loss and malnutrition. The gold standard for diagnosing SIBO is still microbial investigation of jejunal aspirates. Non-invasive hydrogen and methane breath tests are most commonly used for the diagnosis of SIBO using glucose or lactulose. Therapy for SIBO must be complex, addressing all causes, symptoms and complications, and fully individualised. It should include treatment of the underlying disease, nutritional support and cyclical gastro-intestinal selective antibiotics. Prognosis is usually serious, determined mostly by the underlying disease that led to SIBO.

Stress-related modulation of inflammation in experimental models of bowel disease and post-infectious irritable bowel syndrome: role of corticotropin-releasing factor receptors

The interaction between gut inflammatory processes and stress is gaining increasing recognition. Corticotropin-releasing factor (CRF)-receptor activation in the brain is well established as a key signaling pathway initiating the various components of the stress response including in the viscera. In addition, a local CRF signaling system has been recently established in the gut. This review summarize the present knowledge on mechanisms through which both brain and gut CRF receptors modulate intestinal inflammatory processes and its relevance towards increased inflammatory bowel disease (IBD) activity and post-infectious irritable bowel syndrome (IBS) susceptibility induced by stress.

Chronic abdominal pain in children is associated with high prevalence of abnormal microbial fermentation

BACKGROUND

Chronic abdominal pain (CAP) in children, a condition that accounts for approximately 25% of pediatric gastroenterology office visits, may be a precursor to irritable bowel syndrome in adults. Recently, small intestinal bacterial overgrowth (SIBO) has been reported in 78-84% of IBS patients regardless of their abdominal symptoms, compared to 20% in healthy controls. Aims The aim of this study was, therefore, to assess the prevalence of SIBO in children with CAP.

METHODS

Seventy-five children aged 8-18 years diagnosed with CAP based on the Rome II criteria and 40 healthy controls were enrolled. All subjects underwent a lactulose breath hydrogen test (LBT) to assess for SIBO. Children with CAP also filled out symptom questionnaires.

RESULTS

There was a 91% prevalence of an abnormal LBT suggestive of SIBO in the children with CAP and 35% in controls (odds ratio = 16.7, 95% confidence interval 6.0-57.5, P < 0.0001). A comparison of CAP children with a positive LBT to CAP children with a negative LBT revealed the former had significantly more "urgency to have a bowel movement" (P = 0.049) and experienced less "soiling" (P = 0.016) than those with a negative LBT. No significant differences were found between the two groups in terms of the location of their pain or any other associated symptoms.

CONCLUSIONS

Similar to adults with IBS, there is a significantly higher prevalence of SIBO in children with CAP. Randomized controlled studies are needed to determine if eradication of SIBO will lead to symptom improvement in these patients.