The Influence of Small Intestinal Bacterial Overgrowth in Digestive and Extra-Intestinal Disorders.
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ABSTRACT:
SUBMITTER: Losurdo G
PROVIDER: S-EPMC7279035 | biostudies-literature | 2020 May
REPOSITORIES: biostudies-literature
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The Influence of Small Intestinal Bacterial Overgrowth in Digestive and Extra-Intestinal Disorders.
Losurdo Giuseppe G Salvatore D'Abramo Fulvio F Indellicati Giuseppe G Lillo Chiara C Ierardi Enzo E Di Leo Alfredo A
International journal of molecular sciences 20200516 10
Small intestinal bacterial overgrowth (SIBO) is a condition hallmarked by an increase in the concentration of colonic-type bacteria in the small bowel. Watery diarrhea, bloating, abdominal pain and distension are the most common clinical manifestations. Additionally, malnutrition and vitamin (B12, D, A, and E) as well as minerals (iron and calcium) deficiency may be present. SIBO may mask or worsen the history of some diseases (celiac disease, irritable bowel disease), may be more common in some ...[more]
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Project description:Small intestinal bacterial overgrowth (SIBO) is an under-recognised diagnosis with important clinical implications when untreated. However, the optimal treatment regimen remains unclear.To perform a systematic review and meta-analysis comparing the clinical effectiveness of antibiotic therapies in the treatment of symptomatic patients with documented SIBO.Four databases were searched to identify clinical trials comparing effectiveness of: (i) different antibiotics, (ii) different doses of the same antibiotic and (iii) antibiotics compared with placebo. Data were independently extracted according to predetermined inclusion and exclusion criteria. Study quality was independently assessed. The primary outcome was normalisation of post-treatment breath testing. The secondary outcome was post-treatment clinical response.Of 1356 articles identified, 10 met inclusion criteria. Rifaximin was the most commonly studied antibiotic (eight studies) with overall breath test normalisation rate of 49.5% (95% confidence interval, CI 44.0-55.1) (44.0%-55.1%) then (46.7%-55.5%), then (4.6%-17.8%). Antibiotic efficacy varied by antibiotic regimen and dose. Antibiotics were more effective than placebo, with a combined breath test normalisation rate of 51.1% (95% CI 46.7-55.5) for antibiotics compared with 9.8% (95% CI 4.6-17.8) for placebo. Meta-analysis of four studies favoured antibiotics over placebo for breath test normalisation with an odds ratio of 2.55 (95% CI 1.29-5.04). Clinical response was heterogeneously evaluated among six studies, but tended to correlate with breath test normalisation.Antibiotics appear to be more effective than placebo for breath test normalisation in patients with symptoms attributable to SIBO, and breath test normalisation may correlate with clinical response. Studies were limited by modest quality, small sample size and heterogeneous design. Additional higher quality clinical trials of SIBO therapy are warranted.
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Project description:Small Intestinal Bacterial Overgrowth (SIBO) is a form of dysbiosis that involves increased bacterial colonization of the small intestine with some of the bacteria more characteristic of the colon microbiota. The prevalence of SIBO over recent decades has been estimated to range from 2.5 to 22% (depending on the source) and to increase with age and among individuals with comorbidities. Recently, an increase in the number of diagnosed SIBO cases has been observed, which is primarily due to the availability of noninvasive breath tests that facilitate the diagnostic process. However, SIBO is still both a diagnostic and a therapeutic problem. This review presents the pathophysiology, manifestations, diagnostics, and recommended management of SIBO.
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Project description:Small intestinal bacterial overgrowth (SIBO) is highly prevalent and is associated with numerous gastrointestinal disorders, but the microbes involved remain poorly defined. Moreover, existing studies of microbiome alterations in SIBO have utilized stool samples, which are not representative of the entire gastrointestinal tract. Therefore, we aimed to determine and compare the duodenal microbiome composition in SIBO and non-SIBO subjects, using duodenal aspirates from subjects undergoing standard-of-care esophagogastroduodenoscopy without colon preparation. Using the recently-redefined cutoff for SIBO of >103 colony forming units per milliliter (CFU/mL), 42 SIBO and 98 non-SIBO subjects were identified. Duodenal samples from SIBO subjects had 4x103-fold higher counts than non-SIBO subjects when plated on MacConkey agar (P<0.0001), and 3.8-fold higher counts when plated on blood agar (P<0.0001). Twenty subjects had also undergone lactulose hydrogen breath tests (LHBTs), of whom 7/20 had SIBO. At the 90-minute timepoint, 4/7 SIBO subjects had positive LHBTs (rise in hydrogen (H2) ??20 ppm above baseline), as compared to 2/13 non-SIBO subjects. 16S ribosomal RNA (rRNA) sequencing revealed that SIBO subjects had 4.31-fold higher relative abundance of Proteobacteria (FDR P<0.0001) and 1.64-fold lower Firmicutes (P<0.0003) than non-SIBO subjects. This increased relative abundance of Proteobacteria correlated with decreased ?-diversity in SIBO subjects (Spearman R = 0.4866, P<0.0001) Specific increases in class Gammaproteobacteria correlated with the area-under-the-curve for H2 for 0-90 mins during LHBT (R = 0.630, P = 0.002). Increases in Gammaproteobacteria resulted primarily from higher relative abundances of the family Enterobacteriaceae (FDR P<0.0001), which correlated with the symptom of bloating (Spearman R = 0.185, 2-tailed P = 0.028). Increases in family Aeromonadaceae correlated with urgency with bowel movement (Spearman R = 0.186, 2-tailed P = 0.028). These results validate the >103 CFU/mL cutoff for the definition of SIBO, and also reveal specific overgrowth of Proteobacteria in SIBO vs. non-SIBO subjects, coupled with an altered Proteobacterial profile that correlates with symptom severity. Future research may elucidate host-microbiome interactions underlying these symptoms in SIBO patients.
| S-EPMC7347122 | biostudies-literature
Project description:The overall gut microbial profile of patients with small intestinal bacterial overgrowth (SIBO) has not been thoroughly investigated. We investigated the microbial communities of mucosal specimens from the duodenum, ileum, sigmoid colon, and feces of patients with and without SIBO, as diagnosed by lactulose breath testing. The bacteria present in the mucosal and fecal samples were identified using 16S rRNA gene sequencing. Further analysis was performed using the linear discriminant analysis (LDA) effect size method, random forest analysis, and receiver operating characteristic analysis. The microbial diversities of the fecal samples were significantly lower than those of the mucosal samples from the duodenum, ileum, and sigmoid colon (P < 0.001, P < 0.001, and P < 0.001, respectively), while the bacterial compositions of the ileac mucosal samples and sigmoid mucosal samples were similar. The bacterial composition of either the fecal or duodenal mucosal samples were significantly different from those of the other three groups (ANOSIM R = 0.305, P = 0.001). The bacterial compositions of the mucosal samples of the duodenum, ileum, and sigmoid colon in the SIBO + subjects were significantly different from those of the SIBO- subjects (ANOSIM P = 0.039, 0.002, and 0.007, respectively). The relative abundances of 7, 18, and 8 genera were significantly different (LDA score > 3) in the mucosal samples of the duodenum, ileum, and sigmoid colon between the SIBO + and SIBO- groups. Four genera (Lactobacillus, Prevotella_1, Dialister, and norank_f__Ruminococcaceae) showed similar changes among the mucosal samples of the duodenum, ileum, and sigmoid colon in the SIBO + subjects. A signature consisting of four genera in the duodenal mucosa, three genera in the ileac mucosa, or six genera in the mucosa of the sigmoid colon exhibited predictive power for SIBO (area under the curve = 0.9, 0.93, and 0.87, respectively). This study provides a comprehensive profile of the gut microbiota in patients with SIBO. Dysbiosis was observed in the mucosa-associated gut microbiome but not in the fecal microbiome of patients with SIBO. Furthermore, we identified mucosa-associated taxa that may be potential biomarkers or therapeutic targets of SIBO. Further investigation is needed on their mechanisms and roles in SIBO.
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Project description:AimTo explore whether patients with a defective ileocecal valve (ICV)/cecal distension reflex have small intestinal bacterial overgrowth.MethodsUsing a colonoscope, under conscious sedation, the ICV was intubated and the colonoscope was placed within the terminal ileum (TI). A manometry catheter with 4 pressure channels, spaced 1 cm apart, was passed through the biopsy channel of the colonoscope into the TI. The colonoscope was slowly withdrawn from the TI while the manometry catheter was advanced. The catheter was placed across the ICV so that at least one pressure port was within the TI, ICV and the cecum respectively. Pressures were continuously measured during air insufflation into the cecum, under direct endoscopic visualization, in 19 volunteers. Air was insufflated to a maximum of 40 mmHg to prevent barotrauma. All subjects underwent lactulose breath testing one month after the colonoscopy. The results of the breath tests were compared with the results of the pressures within the ICV during air insufflation.ResultsNineteen subjects underwent colonoscopy with measurements of the ICV pressures after intubation of the ICV with a colonoscope. Initial baseline readings showed no statistical difference in the pressures of the TI and ICV, between subjects with positive lactulose breath tests and normal lactulose breath tests. The average peak ICV pressure during air insufflation into the cecum in subjects with normal lactulose breath tests was significantly higher than cecal pressures during air insufflation (49.33 ± 7.99 mmHg vs 16.40 ± 2.14 mmHg, P = 0.0011). The average percentage difference of the area under the pressure curve of the ICV from the cecum during air insufflations in subjects with normal lactulose breath tests was significantly higher (280.72% ± 43.29% vs 100% ± 0%, P = 0.0006). The average peak ICV pressure during air insufflation into the cecum in subjects with positive lactulose breath tests was not significantly different than cecal pressures during air insufflation 21.23 ± 3.52 mmHg vs 16.10 ± 3.39 mmHg. The average percentage difference of the area under the pressure curve of the ICV from the cecum during air insufflation was not significantly different 101.08% ± 7.96% vs 100% ± 0%. The total symptom score for subjects with normal lactulose breath tests and subjects with positive lactulose breath tests was not statistically different (13.30 ± 4.09 vs 24.14 ± 6.58). The ICV peak pressures during air insufflations were significantly higher in subjects with normal lactulose breath tests than in subjects with positive lactulose breath tests (P = 0.005). The average percent difference of the area under the pressure curve in the ICV from cecum was significantly higher in subjects with normal lactulose breath tests than in subjects with positive lactulose breath tests (P = 0.0012). Individuals with positive lactulose breath tests demonstrated symptom scores which were significantly higher for the following symptoms: not able to finish normal sized meal, feeling excessively full after meals, loss of appetite and bloating.ConclusionCompared to normal, subjects with a positive lactulose breath test have a defective ICV cecal distension reflex. These subjects also more commonly have higher symptom scores.
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Project description:Small intestinal bacterial overgrowth (SIBO) is a heterogenous and poorly understood entity characterised by an excessive growth of select microorganisms within the small intestine. This excessive bacterial biomass, in turn, disrupts host physiology in a myriad of ways, leading to gastrointestinal and non-gastrointestinal symptoms and complications. SIBO is a common cause of non-specific gastrointestinal symptoms in children, such as chronic abdominal pain, abdominal distention, diarrhoea, and flatulence, amongst others. In addition, it has recently been implicated in the pathophysiology of stunting, a disease that affects millions of children worldwide. Risk factors such as acid-suppressive therapies, alterations in gastrointestinal motility and anatomy, as well as impoverished conditions, have been shown to predispose children to SIBO. SIBO can be diagnosed via culture-dependant or culture-independent approaches. SIBO's epidemiology is limited due to the lack of uniformity and consensus of its diagnostic criteria, as well as the paucity of literature available. Antibiotics remain the first-line treatment option for SIBO, although emerging modalities such as probiotics and diet manipulation could also have a role. Herein, we present a state-of-the-art-review which aims to comprehensively outline the most current information on SIBO in children, with particular emphasis on the gut microbiota.
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Project description:BackgroundEvidence on small intestinal bacterial overgrowth (SIBO) in patients with chronic pancreatitis (CP) is conflicting.AimThe purpose of this study was to perform a systematic review and meta-analysis on the prevalence of SIBO in CP and to examine the relationship of SIBO with symptoms and nutritional status.MethodsCase-control and cross-sectional studies investigating SIBO in CP patients were analysed. The prevalence of positive tests was pooled across studies, and the rate of positivity between CP cases and controls was calculated.ResultsIn nine studies containing 336 CP patients, the pooled prevalence of SIBO was 36% (95% confidence interval (CI) 17-60%) with considerable heterogeneity (I2?=?91%). A sensitivity analysis excluding studies employing lactulose breath test gave a pooled prevalence of 21.7% (95% CI 12.7-34.5%) with lower heterogeneity (I2?=?56%). The odds ratio for a positive test in CP vs controls was 4.1 (95% CI 1.6-10.4) (I2?=?59.7%). The relationship between symptoms and SIBO in CP patients varied across studies, and the treatment of SIBO was associated with clinical improvement.ConclusionsOne-third of CP patients have SIBO, with a significantly increased risk over controls, although results are heterogeneous, and studies carry several limitations. The impact of SIBO and its treatment in CP patients deserve further investigation.
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Project description:OBJECTIVES:After subtotal colectomy, 40% of patients report chronic gastrointestinal symptoms and poor quality of life. Its etiology is unknown. We determined whether small intestinal bacterial overgrowth (SIBO) or small intestinal fungal overgrowth (SIFO) cause gastrointestinal symptoms after colectomy. METHODS:Consecutive patients with unexplained abdominal pain, gas, bloating and diarrhea (>1 year), and without colectomy (controls), and with colectomy were evaluated with symptom questionnaires, glucose breath test (GBT) and/or duodenal aspiration/culture. Baseline symptoms, prevalence of SIBO/SIFO, and response to treatment were compared between groups. RESULTS:Fifty patients with colectomy and 50 controls were evaluated. A significantly higher (p = 0.005) proportion of patients with colectomy, 31/50 (62%) had SIBO compared to controls 16/50 (32%). Patients with colectomy had significantly higher (p = 0.017) prevalence of mixed SIBO/SIFO 12/50 (24%) compared to controls 4/50 (8%). SIFO prevalence was higher in colectomy but not significant (p = 0.08). There was higher prevalence of aerobic organisms together with decreased anaerobic and mixed organisms in the colectomy group compared to controls (p = 0.008). Patients with colectomy reported significantly greater severity of diarrhea (p = 0.029), vomiting (p < 0.001), and abdominal pain (p = 0.05) compared to controls, at baseline. After antibiotics, 74% of patients with SIBO/SIFO in the colectomy and 69% in the control group improved (p = 0.69). CONCLUSION:Patients with colectomy demonstrate significantly higher prevalence of SIBO/SIFO and greater severity of gastrointestinal symptoms. Colectomy is a risk factor for SIBO/SIFO.
| S-EPMC5915536 | biostudies-literature
Project description:ObjectivesThe composition of the small intestinal microbiota has not yet been characterized thoroughly using culture-independent techniques. We compared small intestinal microbial communities in patients with and without small intestinal bacterial overgrowth (SIBO) using culture-dependent and culture-independent bacterial identification approaches.MethodsSmall bowel aspirate and mucosal samples were collected from patients with suspected SIBO. The aspirates were cultured to diagnose SIBO, defined as ≥10 colony-forming units/mL coliform or ≥10 colony-forming units/mL upper aerodigestive tract bacteria. Bacteria in the aspirates and mucosa were identified using 16S rRNA gene sequencing. We compared small intestinal microbiome composition between groups with and without a culture-based SIBO diagnosis.ResultsAnalysis of the aspirate and mucosal microbial communities from 36 patients revealed decreased α-diversity but no differences in β-diversity in patients with SIBO compared with those without SIBO. There were no significant differences in the relative abundance of individual taxa from the aspirates or mucosa after adjustment for false discovery rate between patients with and without SIBO. Subgroup analysis revealed significant differences in mucosal β-diversity between the coliform and upper aerodigestive tract subgroups. Relative abundances of a mucosal Clostridium spp. (P = 0.05) and an aspirate Granulicatella spp. (P = 0.02) were higher in coliform SIBO vs non-SIBO subgroups. The microbial composition and relative abundance of multiple taxa significantly differed in the mucosal and aspirate specimens.DiscussionCulture-based results of small bowel aspirates do not correspond to aspirate microbiota composition but may be associated with species richness of the mucosal microbiota.
| S-EPMC6736222 | biostudies-literature
Project description:Background/aimsThe pathophysiology of functional abdominal bloating and distention (FABD) is unclear yet. Our aim is to compare the diversity and composition of fecal microbiota in patients with FABD and healthy individuals, and to evaluate the relationship between small intestinal bacterial overgrowth (SIBO) and dysbiosis.MethodsThe microbiota of fecal samples was analyzed from 33 subjects, including 12 healthy controls and 21 patients with FABD diagnosed by the Rome IV criteria. FABD patients underwent a hydrogen breath test. Fecal microbiota composition was determined by 16S ribosomal RNA amplification and sequencing.ResultsOverall fecal microbiota composition of the FABD group differed from that of the control group. Microbial diversity was significantly lower in the FABD group than in the control group. Significantly higher proportion of Proteobacteria and significantly lower proportion of Actinobacteria were observed in FABD patients, compared with healthy controls. Compared with healthy controls, significantly higher proportion of Faecalibacterium in FABD patients and significantly higher proportion of Prevotella and Faecalibacterium in SIBO (+) patients with FABD were found. Faecalibacterium prausnitzii, was significantly more abundant, but Bacteroides uniformis and Bifidobacterium adolescentis were significantly less abundant in patients with FABD, compared with healthy controls. Significantly more abundant Prevotella copri and F. prausnitzii, and significantly less abundant B. uniformis and B. adolescentis were observed in SIBO (+) patients, compared with healthy controls.ConclusionThe fecal microbiota profiles in FABD patients are different from those in healthy controls, particularly in SIBO (+) patients, suggesting a role of gut microbiota in the pathogenesis of FABD.
| S-EPMC7547202 | biostudies-literature