Altered profiles of intestinal microbiota and organic acids may be the origin of symptoms in irritable bowel syndrome.
ABSTRACT The profile of intestinal organic acids in irritable bowel syndrome (IBS) and its correlation with gastrointestinal (GI) symptoms are not clear. We hypothesized in this study that altered GI microbiota contribute to IBS symptoms through increased levels of organic acids.
Subjects were 26 IBS patients and 26 age- and sex-matched controls. Fecal samples were collected for microbiota analysis using quantitative real-time polymerase chain reaction and culture methods, and the determination of organic acid levels using high-performance liquid chromatography. Abdominal gas was quantified by image analyses of abdominal X-ray films. Subjects completed a questionnaire for GI symptoms, quality of life (QOL) and negative emotion.
Irritable bowel syndrome patients showed significantly higher counts of Veillonella (P = 0.046) and Lactobacillus (P = 0.031) than controls. They also expressed significantly higher levels of acetic acid (P = 0.049), propionic acid (P = 0.025) and total organic acids (P = 0.014) than controls. The quantity of bowel gas was not significantly different between controls and IBS patients. Finally, IBS patients with high acetic acid or propionic acid levels presented with significantly worse GI symptoms, QOL and negative emotions than those with low acetic acid or propionic acid levels or controls.
These results support the hypothesis that both fecal microbiota and organic acids are altered in IBS patients. A combination of Veillonella and Lactobacillus is known to produce acetic and propionic acid. High levels of acetic and propionic acid may associate with abdominal symptoms, impaired QOL and negative emotions in IBS.
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ABSTRACT: OBJECTIVE: Previous studies have reported that patients with irritable bowel syndrome (IBS) show high neuroticism. However, the precise association between the IBS subtypes and the degree of neuroticism in younger populations is largely unknown. We tested our hypothesis that subjects with diarrhea-predominant IBS may have a higher degree of neuroticism than subjects without IBS or those with other subtypes of IBS. We also verified the additional hypothesis that the severity of neuroticism might be correlated with the severity of IBS in younger populations. METHODS: We conducted a cross-sectional survey of 557 university students, ranging in age from 18 to 21 years. Presence/ absence of IBS and determination of the IBS subtype was by the Rome II Modular Questionnaire, while the severity of IBS was determined by the IBS severity index (IBS-SI). The degree of neuroticism was evaluated using the Maudsely Personality Inventory (MPI). The presence/absence of psychological distress was measured with the K6 scale. RESULTS: Neuroticism scores in the subjects with diarrhea-predominant IBS were significantly higher than those in the non-IBS subjects or subjects with constipation-predominant IBS. The neuroticism scores were significantly correlated with the IBS-SI scores in all subjects with IBS. CONCLUSION: These results suggest that neuroticism is involved in the pathophysiology of IBS in young subjects, especially in that of the diarrhea-predominant subtype.BioPsychoSocial Medicine 10/2012; 6(1):20.
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ABSTRACT: Diagnosing irritable bowel syndrome (IBS) can be a challenge; many clinicians resort to invasive investigations in order to rule out other diseases and reassure their patients. Volatile organic metabolites (VOMs) are emitted from feces; understanding changes in the patterns of these VOMs could aid our understanding of the etiology of the disease and the development of biomarkers, which can assist in the diagnosis of IBS. We report the first comprehensive study of the fecal VOMs patterns in patients with diarrhea-predominant IBS (IBS-D), active Crohn's disease (CD), ulcerative colitis (UC) and healthy controls. 30 patients with IBS-D, 62 with CD, 48 with UC and 109 healthy controls were studied. Diagnosis of IBS-D was made using the Manning criteria and all patients with CD and UC met endoscopic, histologic and/or radiologic criteria. Fecal VOMs were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). 240 VOMs were identified. Univariate analysis showed that esters of short chain fatty acids, cyclohexanecarboxylic acid and its ester derivatives were associated with IBS-D (p<0.05), while aldehydes were more abundant in IBD (p<0.05). A predictive model, developed by multivariate analysis, separated IBS-D from active CD, UC and healthy controls with a sensitivity of 94%, 96% and 90%; and a specificity of 82%, 80% and 80% respectively (p<0.05). The understanding of the derivation of these VOMs may cast light on the etiology of IBS-D and IBD. These data show that fecal VOMs analyses could contribute to the diagnosis of IBS-D, for which there is no laboratory test, as well as IBD.PLoS ONE 01/2013; 8(3):e58204. · 4.09 Impact Factor
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ABSTRACT: Metagenomics which combines the power of genomics, bioinformatics, and systems biology, provide new access to the microbial world. Metagenomics permit the genetic analysis of complex microbial populations without requiring prior cultivation. Through the conceptual innovations in metagenomics and the improvements in DNA high-throughput sequencing and bioinformatics analysis technology, gastrointestinal microbiology has entered the metagenomics era and become a hot topic worldwide. Human microbiome research is underway, however, most studies in this area have focused on the composition and function of the intestinal microbiota and the relationship between intestinal microbiota and metabolic diseases (obesity, diabetes, metabolic syndrome, etc.) and intestinal disorders [inflammatory bowel disease, colorectal cancer, irritable bowel syndrome (IBS), etc.]. Few investigations on microbiota have been conducted within the upper gastrointestinal tract (esophagus, stomach and duodenum). The upper gastrointestinal microbiota is essential for several gastrointestinal illnesses, including esophagitis, Barrett's esophagus, and esophageal carcinoma, gastritis and gastric cancer, small intestinal bacterial overgrowth, IBS and celiac disease. However, the constitution and diversity of the microbiota in different sections of the upper gastrointestinal tract under health and various disease states, as well as the function of microbiota in the pathogenesis of various digestive diseases are still undefined. The current article provides an overview of the recent findings regarding the relationship between upper gastrointestinal microbiota and gastrointestinal diseases; and discusses the study limitations and future directions of upper gastrointestinal microbiota research.World Journal of Gastroenterology 03/2013; 19(10):1541-50. · 2.47 Impact Factor