Role of colonic fermentation in the perception of colonic distention in irritable bowel syndrome and functional bloating.
ABSTRACT Bloating represents a frequent gastrointestinal symptom, but the pathophysiologic mechanism responsible for its onset is still largely unknown. Patients very frequently attribute the sensation of bloating to the presence of excessive bowel gas, but not all patients with gas-related symptoms exhibit increased intestinal production of gas. It is therefore possible that other still unrecognized mechanisms might contribute to its pathophysiology. Our aim was to evaluate whether a subgroup of patients affected by functional abdominal bloating presents hypersensitivity to colonic fermentation.
Sixty patients affected by functional gastrointestinal disorders (11 functional bloating, 36 constipation-predominant, and 13 diarrhea-predominant irritable bowel syndrome) and moderate to severe bloating took part in the study. Twenty sex- and age-matched healthy volunteers were enrolled as a control group. All the subjects underwent a preliminary evaluation of breath hydrogen excretion after oral lactulose. Then, on a separate day, an evaluation of sensitivity thresholds at rectal level was performed with a barostat before and after the induction of colonic fermentation with oral lactulose. A control test with electrolyte solution was also performed.
Both breath hydrogen excretion and mouth-to-cecum transit time did not differ between the 4 groups studied. Neither electrolyte solution nor lactulose modified sensitivity thresholds in healthy volunteers. In low hydrogen producers, basal perception and discomfort thresholds were similar to high hydrogen producers, but after lactulose both perception and discomfort thresholds were significantly reduced only in low hydrogen producers.
A subgroup of patients with functional gastrointestinal disorders and moderate to severe bloating might have hypersensitivity to products of colonic fermentation.
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ABSTRACT: Irritable bowel syndrome (IBS) is a multifactorial disease. The pathophysiological focus has recently been on the likely significant role played by anomalies of gut microbiota, particularly in the sensitisation of sensory nerve endings and the activation of immune cells in the digestive tract walls. Epidemiologically, IBS, especially the diarrhoeapredominant form, can appear following an acute episode of gastroenteritis, mainly of bacterial origin. The metabolic action of the microbiota appears to be overly responsive and can result in certain symptoms, such as bloating, and might facilitate the occurrence of visceral hypersensitivity. Qualitative anomalies of the microbiota have been described at both the endoluminal level and the thin layer in contact with the epithelium. Lastly, endoluminal bacterial overgrowth seems to be present in a subgroup of patients with IBS, although it is not currently known whether this anomaly is primary or secondary to motor disorders, especially in the small bowel, which are seen during IBS. Knowledge of this deleterious role of the microbiota opens the way to new therapeutic options, with a possible use of prebiotics or probiotics, as well as antibiotics.Gastroentérologie Clinique et Biologique 09/2010; 34(4):56-60. · 1.14 Impact Factor
Article: Bacterial flora, gas and antibiotics[Show abstract] [Hide abstract]
ABSTRACT: The human gastrointestinal microflora is a complex ecosystem with about 500 different bacterial species. In healthy individuals, the human stomach and the proximal small bowel contain only a few bacterial species, with the terminal ileum considered a transitional zone between the proximal small bowel aerobic microflora and the colonic anaerobic bacteria. The colon hosts a complex and variegate microbiota, including anaerobes (bacteroides, bifidobacteria, lactobacilli and clostridium), and several other species. The enteric microflora is involved in protective, trophic and metabolic functions. The interaction between gut microflora and substrate leads to gas production, while their overproduction can be responsible of the “gas-related syndrome”, a constellation of non-specific gastrointestinal symptoms (bloating, borborygms, flatulence, abdominal distension and discomfort). Any condition leading to the perturbation of the equilibrium between enteric flora and the surrounding system is a predisposing factor for bacterial overgrowth. Proposed antimicrobic treatments, including tetracycline and norfloxacin, amoxicillin-clavulanic acid and S. Boulardii, are still highly empiric. The efficacy of rifaximin, a non-absorbable antibiotic with bactericidal action against anaerobes and aerobes and a low toxicity, has been evaluated in patients with small intestinal bacterial overgrowth and gas-related syndrome, and has a potential therapeutic role in a subgroup of patients.Digestive and Liver Disease Supplements 07/2009; 3(2):54-57.
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ABSTRACT: Irritable bowel syndrome patients with diarrhoea (IBS-D) often report intolerance to milk; however, the mechanism underlying these symptoms is unknown. To assess the role of psychological factors, immune activation and visceral sensitivity on the development of lactose intolerance (LI) in IBS-D patients. Fifty-five IBS-D patients and 18 healthy controls (HCs) with lactase deficiency underwent a 20-g lactose hydrogen breath test (LHBT). Patients were categorised as lactose malabsorption (LM; malabsorption only) or LI [malabsorption plus increase in total symptom score (TSS). Measurements included (i) psychological status; (ii) enteric biopsies with quantification of mast cells (MCs), T-lymphocytes and enterochromaffin cells; (iii) serum cytokines; (iv) rectal sensitivity before and after lactose ingestion. LI was more prevalent in IBS-D patients than HCs [25/55 (46%) vs. 3/18 (17%), P = 0.029]. IBS-D patients with LI had (i) higher levels of anxiety than those with LM (P = 0.017) or HCs (P = 0.006); (ii) increased mucosal MCs compared with LM (P = 0.006) and HCs (P < 0.001); (iii) raised serum TNF-α compared with LM (P = 0.034) and HCs (P < 0.001) and (iv) increased rectal sensitivity after lactose ingestion compared with LM (P < 0.001) or HCs (P < 0.001). Severity of abdominal symptoms after lactose ingestion was associated with the increase in visceral sensitivity after lactose intake (r = 0.629, P < 0.001), MCs (r = 0.650, P < 0.001) and anxiety (r = 0.519, P < 0.001). IBS-D patients with lactose intolerence are characterised by anxiety, mucosal immune activation and increased visceral sensitivity after lactose ingestion. The presence of these biomarkers may indicate an IBS phenotype that responds to dietary therapy and/or mast cell stabilisers (ClinicalTrials.gov Identifier: NCT01286597).Alimentary Pharmacology & Therapeutics 12/2013; · 4.55 Impact Factor