Hydrogen glucose breath test to detect small intestinal bacterial overgrowth: a prevalence case-control study in irritable bowel syndrome

Body constitutions of traditional Chinese medicine caused a significant effect on irritable bowel syndrome

BACKGROUND

According to the theory of traditional Chinese medicine (TCM), all types of body constitutions, except for the Gentleness (ie, the control group in our study), have disease susceptibility and affect the disease development process. This study attempted to investigate the relationship between TCM body constitutions and irritable bowel syndrome (IBS).

METHODS

This cross-sectional study was based on Taiwan Biobank (TWB) and collected clinical data from 13 941 subjects aged 30 to 70. The results of the study showed that subjects with Yang-deficiency (N = 3161 subjects, odds ratio [OR] = 2.654, 95% CI = 1.740-3.910), Ying-deficiency (N = 3331 subjects, OR = 1.096, 95% CI = 0.627-1.782) or Stasis (N = 2335 subjects, OR = 1.680, 95% CI = 0.654-3.520) were more likely to have IBS.

RESULTS

If the subjects with two or more TCM body constitutions: Yang-deficiency + Ying-deficiency (OR = 3.948, 95% CI = 2.742-5.560), Yang-deficiency + Stasis (OR = 2.312, 95% CI = 1.170-4.112), Ying-deficiency + Stasis (OR = 1.851, 95% CI = 0.828-3.567), or Yang-deficiency + Ying-deficiency + Stasis (OR = 3.826, 95% CI = 2.954-4.932) were also prone to IBS.

CONCLUSION

These results confirmed the high correlation between TCM body constitutions and IBS. Because the current treatment for IBS is not entirely satisfactory, integrated traditional Chinese and Western medicine might provide patients with an alternative treatment option to alleviate IBS.

Comparison of jejunal aspirate culture and methane and hydrogen breath test in the diagnosis of small intestinal bacterial overgrowth

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) is still difficult to diagnose. Quantitative culture of small intestine aspirate is recommended to be the gold standard. The methane and hydrogen breath tests are easily repeatable, sufficiently sensitive and highly specific for SIBO diagnosis. Our goal is to contrast the diagnostic value of the breath tests with jejunal aspiration cultures.

METHODS

40 adult outpatients (age < 60) were enrolled in our study. Randomly, within 2 days, both the methane and the hydrogen breath test and jejunal aspiration culture were performed on each patient and the results of both tests were evaluated and contrasted.

RESULTS

The jejunal culture was positive (105CFU / mL) in 14/40(35%) subjects, the lactulose breath test (LBT) was positive in 18/40 (45%) subjects, and the glucose breath test (GBT) was positive in 12/40 (30%). The GBT showed good agreement (κ = 0.659) and LBT showed poor agreement (κ = 0.588) with the jejunal aspirate culture. The sensitivity, specificity, positive and negative predictive values of LBT/GBT were 85.7/71.4%,76.9/92.3%, 66.6/83.3% and 90.9/85.7%, respectively.

CONCLUSIONS

35% of patients with suspected SIBO are identified using jejunal aspirate cultures. For the identification of SIBO, GBT is more specific than LBT, but has a lower sensitivity. In individuals with suspected SIBO, the breath test should be initially due to its good agreement with the jejunal aspirate culture.

High Prevalence of Small Intestinal Bacterial Overgrowth Syndrome in ICU Patients: An Observational Study

Background: Small intestinal bacterial overgrowth (SIBO), although associated with potentially serious complications, has not been adequately studied in critically ill patients. The primary objective of this study was to assess the prevalence of SIBO in critically ill patients. Secondary outcomes included the assessment of its effect on ventilator-associated pneumonia (VAP), intensive care unit (ICU) length of stay (LOS), and all-cause in-hospital mortality rate. Methods: This prospective observational study was conducted in a mixed medical-surgical ICU. In 52 consecutive ICU patients, a noninvasive modified hydrogen breath test (HBT) with lactulose was employed for SIBO diagnosis. The HBT was conducted at predetermined time intervals (first day of admission; third, fifth, and seventh day of ICU stay). Patients with an abnormal HBT suggesting SIBO on the day of ICU admission were excluded from the study. Participants were classified as either positive or negative based on their HBT on the third, fifth, and/or seventh day. A comparative assessment of demographic data, APACHE II score, incidence of VAP, duration of ICU stay, and all-cause in-hospital mortality was conducted. Multivariate logistic regression analysis was performed to identify the predictive factors for SIBO. Results: The groups were homogeneous in terms of their baseline characteristics. The prevalence of SIBO was 36.5%. The all-cause in-hospital mortality was 34.6%. The presence of SIBO was associated with an increased incidence of VAP (P < .001) and a prolonged ICU length of stay (P < .033). All-cause in-hospital mortality was similar between the groups. Regarding the results of the multivariate logistic regression model, only age was identified as a statistically significant independent predictor of SIBO (OR 1.08, P = .018). Conclusions: The prevalence of SIBO in ICU patients appears to be increased. Both early diagnosis and effective treatment are of utmost importance, especially for critically ill patients since it appears to be associated with VAP and prolonged hospitalization.

Show Me What You Have Inside-The Complex Interplay between SIBO and Multiple Medical Conditions-A Systematic Review

The microbiota, as a complex of microorganisms in a particular ecosystem, is part of the wider term-microbiome, which is defined as the set of all genetic content in the microbial community. Imbalanced gut microbiota has a great impact on the homeostasis of the organism. Dysbiosis, as a disturbance in bacterial balance, might trigger or exacerbate the course of different pathologies. Small intestinal bacterial overgrowth (SIBO) is a disorder characterized by differences in quantity, quality, and location of the small intestine microbiota. SIBO underlies symptoms associated with functional gastrointestinal disorders (FGD) as well as may alter the presentation of chronic diseases such as heart failure, diabetes, etc. In recent years there has been growing interest in the influence of SIBO and its impact on the whole human body as well as individual systems. Therefore, we aimed to investigate the co-existence of SIBO with different medical conditions. The PubMed database was searched up to July 2022 and we found 580 original studies; inclusion and exclusion criteria let us identify 112 eligible articles, which are quoted in this paper. The present SIBO diagnostic methods could be divided into two groups-invasive, the gold standard-small intestine aspirate culture, and non-invasive, breath tests (BT). Over the years scientists have explored SIBO and its associations with other diseases. Its role has been confirmed not only in gastroenterology but also in cardiology, endocrinology, neurology, rheumatology, and nephrology. Antibiotic therapy could reduce SIBO occurrence resulting not only in the relief of FGD symptoms but also manifestations of comorbid diseases. Although more research is needed, the link between SIBO and other diseases is an important pathway for scientists to follow.

Quantitative sequencing clarifies the role of disruptor taxa, oral microbiota, and strict anaerobes in the human small-intestine microbiome

BACKGROUND

Upper gastrointestinal (GI) disorders and abdominal pain afflict between 12 and 30% of the worldwide population and research suggests these conditions are linked to the gut microbiome. Although large-intestine microbiota have been linked to several GI diseases, the microbiota of the human small intestine and its relation to human disease has been understudied. The small intestine is the major site for immune surveillance in the gut, and compared with the large intestine, it has greater than 100 times the surface area and a thinner and more permeable mucus layer.

RESULTS

Using quantitative sequencing, we evaluated total and taxon-specific absolute microbial loads from 250 duodenal-aspirate samples and 21 paired duodenum-saliva samples from participants in the REIMAGINE study. Log-transformed total microbial loads spanned 5 logs and were normally distributed. Paired saliva-duodenum samples suggested potential transmission of oral microbes to the duodenum, including organisms from the HACEK group. Several taxa, including Klebsiella, Escherichia, Enterococcus, and Clostridium, seemed to displace strict anaerobes common in the duodenum, so we refer to these taxa as disruptors. Disruptor taxa were enriched in samples with high total microbial loads and in individuals with small intestinal bacterial overgrowth (SIBO). Absolute loads of disruptors were associated with more severe GI symptoms, highlighting the value of absolute taxon quantification when studying small-intestine health and function.

CONCLUSION

This study provides the largest dataset of the absolute abundance of microbiota from the human duodenum to date. The results reveal a clear relationship between the oral microbiota and the duodenal microbiota and suggest an association between the absolute abundance of disruptor taxa, SIBO, and the prevalence of severe GI symptoms. Video Abstract.

The Role of Leaky Gut in Nonalcoholic Fatty Liver Disease: A Novel Therapeutic Target

The liver directly accepts blood from the gut and is, therefore, exposed to intestinal bacteria. Recent studies have demonstrated a relationship between gut bacteria and nonalcoholic fatty liver disease (NAFLD). Approximately 10–20% of NAFLD patients develop nonalcoholic steatohepatitis (NASH), and endotoxins produced by Gram-negative bacilli may be involved in NAFLD pathogenesis. NAFLD hyperendotoxicemia has intestinal and hepatic factors. The intestinal factors include impaired intestinal barrier function (leaky gut syndrome) and dysbiosis due to increased abundance of ethanol-producing bacteria, which can change endogenous alcohol concentrations. The hepatic factors include hyperleptinemia, which is associated with an excessive response to endotoxins, leading to intrahepatic inflammation and fibrosis. Clinically, the relationship between gut bacteria and NAFLD has been targeted in some randomized controlled trials of probiotics and other agents, but the results have been inconsistent. A recent randomized, placebo-controlled study explored the utility of lubiprostone, a treatment for constipation, in restoring intestinal barrier function and improving the outcomes of NAFLD patients, marking a new phase in the development of novel therapies targeting the intestinal barrier. This review summarizes recent data from studies in animal models and randomized clinical trials on the role of the gut–liver axis in NAFLD pathogenesis and progression.

Pharmacokinetics and Safety of Rifamycin SV after Single and Multiple Doses of MMX® Modified Release Tablets in Healthy Male and Female Volunteers

The primary objective of this single- and multiple-dose pharmacokinetic study was the investigation of rifamycin SV’s pharmacokinetic profile in plasma and urine. All the 18 enrolled healthy men and post-menopausal women received modified release tablets containing 600 mg of the oral non-absorbable antibiotic, rifamycin SV, according to a multiple dose regimen: one tablet three times a day (daily intake: 1800 mg) for 14 consecutive days. Blood sampling and urine collection were performed up to 24 h post-dose after the first dose on Days 1 and 7. On average, on Day 1, C_max,0–24 was 5.79 ± 4.24 ng/mL and was attained in a median time of 9 h. On Day 7, all the subjects had quantifiable levels of rifamycin SV in plasma at each sampling time. After a peak concentration attained 2 h post-dose (mean ± SD concentration: 10.94 ± 16.41 ng/mL), rifamycin SV decreased in plasma to levels similar to those of Day 1. The amounts of rifamycin SV excreted in urine paralleled the plasma concentration at the corresponding times. On Day 1, the total amount excreted in urine was 0.0013%, and was 0.0029% on Day 7. The study results confirmed those of the previous Phase I study: the systemic absorption of rifamycin SV was also proved negligible after 7 days of the 600 mg t.i.d. dose regimen of the newly formulated tablets, currently under development for the treatment of several small and large intestinal pathologies, including diarrhea-predominant irritable bowel syndrome, hepatic encephalopathy, and others. Registered at ClinicalTrials.gov with the identifier NCT02969252, last updated on 26JAN18.

Low-Temperature Hydrogen Sensor: Enhanced Performance Enabled through Photoactive Pd-Decorated TiO2 Colloidal Crystals

The high demand for H₂ gas sensors is not just limited to industrial process control and leak detection applications but also extends to the food and medical industry to determine the presence of various types of bacteria or underlying medical conditions. For instance, sensing of H₂ at low concentrations (<10 ppm) is essential for developing breath analyzers for the noninvasive diagnosis of some gastrointestinal diseases. However, there are major challenges to overcome in order to achieve high sensitivity and hence low limit of detection (LoD) toward H₂. In this study, it is demonstrated that light-assisted amperometric gas sensors employing sensitive layers based on Pd-decorated TiO₂ long-range ordered crystals can achieve excellent H₂ sensing performance. This unique combination of materials and novel layered structure enables the detection of H₂ gas down to 50 ppm with highly promising LoD capabilities. The sensor response profiles revealed that the sensor's signal-to-noise ratio was higher in the presence of light when operated with a 9 V bias (relative to other conditions used), producing a LoD of only 3.5 ppm at an operating temperature of 33 °C. The high performance of the sensor makes it attractive for applications that require low-level (ppm as opposed to conventional % levels) H₂ gas detection. Most importantly, the developed sensor exhibited high selectivity (>93%) toward H₂ over other gas species such as CO₂, C₄H₈O, C₃H₆O, CH₃CHO, and NO, which are commonly found to coexist in the environment.

A meta-analysis on small intestinal bacterial overgrowth in patients with different subtypes of irritable bowel syndrome

BACKGROUND

Enteric microbiota is increasingly being recognized as an important factor in the pathogenesis of irritable bowel syndrome (IBS). The reported prevalence of small intestinal bacterial overgrowth (SIBO) in subjects with IBS is highly variable, and there is no consensus on the role of SIBO in different subtypes of IBS, and indications and methods of testing.

METHODS

A comprehensive literature search was performed for studies applying tests for SIBO in subjects with IBS. After applying prospectively decided exclusion criteria, the eligible papers were examined using a meta-analysis approach for the prevalence of SIBO in subjects with IBS using different tests. The odds ratios of SIBO among subjects with IBS as compared with healthy controls using different tests were calculated.

RESULTS

Of the available studies (22, 17, 5, and 3 using lactulose and glucose hydrogen breath tests [LHBT and GHBT], jejunal aspirate culture, and more than one tests, respectively) meeting the inclusion criteria, 36.7% (95% confidence interval [CI] 24.2-44.6) had a positive test for SIBO. Patients with IBS were 2.6 (95% CI 1.3-6.9) and 8.3 (95% CI 3.0-5.9) times more likely to have a positive test for SIBO as compared with healthy controls using GHBT and jejunal aspirate culture, respectively. Patients with diarrhea-predominant IBS were more likely to have positive GHBT as compared with the other subtypes.

CONCLUSIONS

Patients with IBS were more likely to have SIBO as compared with healthy subjects using GHBT and jejunal aspirate culture but not using LHBT. Patients with diarrhea-predominant IBS more often have SIBO.

The Influence of Small Intestinal Bacterial Overgrowth in Digestive and Extra-Intestinal Disorders

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 extra-intestinal disorders (scleroderma, obesity), or could even represent a pathogenetic link with some diseases, in which a perturbation of intestinal microbiota may be involved. On these bases, we performed a review to explore the multiple links between SIBO and digestive and extra-intestinal diseases.

Effect of a Preparation of Four Probiotics on Symptoms of Patients with Irritable Bowel Syndrome: Association with Intestinal Bacterial Overgrowth

The effect of probiotics on small intestinal bacterial overgrowth (SIBO) in irritable bowel syndrome (IBS) has never been studied so far. In this prospective trial, five patients with IBS and SIBO and 21 patients with IBS without SIBO were administered an oral capsule containing Saccharomyces boulardii, Bifidobacterium lactis, Lactobacillus acidophilus, and Lactobacillus plantarum (Lactolevure^®) every 12 h for 30 days. SIBO was defined by quantitative culture of the third part of the duodenum; IBS was defined by the Rome III criteria. Severity of symptoms was graded by the IBS severity scoring system (SSS). The primary study endpoint was the efficacy of probiotics in improvement of symptoms of IBS in patients with SIBO. Thirty days after the end of treatment, a 71.3% decrease of the total IBS score was detected in patients with IBS and SIBO compared to 10.6% in those without SIBO (p 0.017). A similar decrease was achieved among patients with constipation-predominant IBS without SIBO. Post-treatment satisfaction from bowel function was greater in patients with SIBO. Similar satisfaction improvement was found among patients with diarrhea-predominant IBS irrespective from SIBO; pain intensity score decreased in patients with constipation-predominant IBS irrespective from SIBO. The benefit of probiotics was greater among patients with a pro-inflammatory cytokine pattern in the duodenal fluid. This is the first study that prospectively demonstrated superior clinical efficacy of probiotics in patients with IBS with SIBO. Analysis also showed considerable benefit from probiotic intake regarding certain symptoms of patients with diarrhea-predominant and constipation-predominant IBS.Trial registration: ClinicalTrials.gov identifier NCT02204891.

Irritable bowel syndrome and gut microbiota

PURPOSE OF REVIEW

To provide an overview of recent studies exploring the gut microbiota in pathogenesis and treatment of irritable bowel syndrome (IBS).

RECENT FINDINGS

Primary bacterial gut disturbances have been linked to the development and severity of IBS. Dysbiosis, or alteration in the normal intestinal flora, modulates intestinal permeability, inflammation, gut motility and likely quality of life. These biomechanical changes are associated with enteric and central nervous system processing as well. When compared to healthy controls, IBS patients display poor quality of life measures and are at increased risk of depression and anxiety. The severity of psychological and gastrointestinal symptoms in IBS has been linked with a distinct intestinal microbiota signature. Efforts to modulate intestinal dysbiosis in IBS have shown little improvement in large systematic reviews. The low FODMAP diet reduces bacteria, such as Bifidobacterum and Actinobacteria. Although rifaximin improves symptoms, it may only stimulate a transient effect on the gut microbiota. Fecal microbiota transplant does not provide prolonged symptom relief in IBS.

SUMMARY

This review elucidates recent advances in IBS and the gut microbiota. Microbiota changes are one underlying factor in perpetuating global IBS symptoms. The opportunity to exploit this disturbance through treatment modalities requires further investigation.

Small Intestinal Bacterial Overgrowth in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Case-Control Studies

INTRODUCTION

We conducted a systematic review and meta-analysis to compare the prevalence of small intestinal bacterial overgrowth (SIBO) in patients with irritable bowel syndrome (IBS) and controls.

METHODS

Electronic databases were searched up to December 2018 for studies reporting SIBO prevalence in patients with IBS. Prevalence rates, odds ratios (ORs), and 95% confidence intervals (CIs) of SIBO in patients with IBS and controls were calculated.

RESULTS

We included 25 studies with 3,192 patients with IBS and 3,320 controls. SIBO prevalence in patients with IBS was significantly increased compared with controls (OR = 3.7, 95% CI 2.3-6.0). In studies using only healthy controls, the OR for SIBO in patients with IBS was 4.9 (95% CI 2.8-8.6). With breath testing, SIBO prevalence in patients with IBS was 35.5% (95% CI 33.6-37.4) vs 29.7% (95% CI 27.6-31.8) in controls. Culture-based studies yielded a SIBO prevalence of 13.9% (95% CI 11.5-16.4) in patients with IBS and 5.0% (95% CI 3.9-6.2) in controls with a cutoff value of 10 colony-forming units per milliliter vs 33.5% (95% CI 30.1-36.9) in patients with IBS and 8.2% (95% CI 6.8-9.6) in controls with a cutoff value of 10 colony-forming unit per milliliter, respectively. SIBO prevalence diagnosed by lactulose breath test is much greater in both patients with IBS (3.6-fold) and controls (7.6-fold) compared with glucose breath test. Similar difference is seen when lactulose breath test is compared with culture methods. OR for SIBO in patients with IBS-diarrhea compared with IBS-constipation was 1.86 (95% CI 1.83-2.8). Methane-positive breath tests were significantly more prevalent in IBS-constipation compared with IBS-diarrhea (OR = 2.3, 95% CI 1.2-4.2). In patients with IBS, proton pump inhibitor was not associated with SIBO (OR = 0.8, 95% CI 0.5-1.5, P = 0.55).

DISCUSSION

This systematic review and meta-analysis suggests a link between IBS and SIBO. However, the overall quality of the evidence is low. This is mainly due to substantial "clinical heterogeneity" due to lack of uniform selection criteria for cases and controls and limited sensitivity and specificity of the available diagnostic tests.

Second-Generation Biomarker Testing for Irritable Bowel Syndrome Using Plasma Anti-CdtB and Anti-Vinculin Levels

BACKGROUND

ELISA testing for anti-CdtB and anti-vinculin can discriminate patients with irritable bowel syndrome with diarrhea (IBS-D) from those with inflammatory bowel disease (IBD). However, recent findings suggest the antigens can suffer from epitope instability.

AIM

This study aimed to assess effects of incorporating epitope stabilization on test characteristics for distinguishing IBS-D from IBD subjects.

METHODS

Plasma samples from IBS-D subjects from a large-scale clinical trial and subjects with endoscopically active IBD without concurrent immunomodulator therapy were used. After epitope stabilization, CdtB and vinculin were used in ELISA testing. Optical density readings were compared between IBS-D and IBD subjects.

RESULTS

Samples from 100 IBS-D and 31 IBD (22 UC and 9 CD) subjects were tested. IBS-D subjects had higher anti-CdtB titers (P = 0.0001) and higher anti-vinculin titers (P = 0.004) than IBD subjects. The specificities of anti-CdtB and anti-vinculin to differentiate IBS-D from IBD were 93.5% and 90.9%, respectively, with sensitivities of 43.0% and 52.2%, respectively. The positive likelihood ratios of identifying IBS-D with anti-CdtB and anti-vinculin were 6.7 and 5.7, respectively. Assuming a pretest probability of 57% for diagnosis of IBS-D in patients with abdominal pain and change in bowel habits, testing positive for both antibodies resulted in a posttest probability of > 98%.

CONCLUSIONS

Performing epitope stabilization for CdtB and vinculin enhances the test characteristics of ELISAs for anti-CdtB and anti-vinculin in discriminating IBS-D from IBD. Measurement of anti-CdtB and anti-vinculin with this second-generation methodology may further advance our understanding of the role of immunity in functional bowel diseases.

Systematic review with meta-analysis: efficacy of faecal microbiota transplantation for the treatment of irritable bowel syndrome

BACKGROUND

Increasing evidence supports the role of the gut microbiota in the aetiology of irritable bowel syndrome (IBS). Faecal microbiota transplantation (FMT) is a highly effective treatment against recurrent Clostridioides difficile infection in randomised controlled trials (RCTs), and may be beneficial in ulcerative colitis. However, its efficacy in IBS is uncertain.

AIM

To perform a systematic review and meta-analysis to examine this issue.

METHODS

We searched MEDLINE, EMBASE, EMBASE Classic, the Cochrane Central Register of Controlled Trials, and clinicaltrials.gov through to March 2019. RCTs recruiting adults with IBS, which compared FMT with placebo, were eligible. Dichotomous symptom data were pooled to obtain a relative risk (RR) of remaining symptomatic after therapy, with a 95% CI.

RESULTS

The search strategy identified 322 citations. Five RCTs were eligible for inclusion, containing 267 patients. Overall, 92.2% of included patients had IBS-D or IBS-M, and only 7.8% IBS-C. When data were pooled for all patients, irrespective of stool type, the RR of IBS symptoms not improving was 0.98 (95% CI 0.58-1.66). Placebo capsules administered orally were superior to capsules containing donor stool in two pooled trials (RR = 1.96; 95% CI 1.19-3.20). FMT from donor stool delivered via colonoscopy was superior to autologous stool in two pooled RCTs (RR = 0.63; 95% CI 0.43-0.93). FMT from donor stool via nasojejunal tube showed a trend towards a benefit over autologous stool in one trial (RR = 0.69; 95% CI 0.46-1.02).

CONCLUSIONS

Fresh or frozen donor stool delivered via colonoscopy or nasojejunal tube may be beneficial in IBS. Larger, more rigorously conducted trials of FMT in IBS are needed.

Prevalence and predictors of small intestinal bacterial overgrowth in irritable bowel syndrome: a systematic review and meta-analysis

BACKGROUND

The reported prevalence of small intestinal bacterial overgrowth (SIBO) among individuals with irritable bowel syndrome (IBS) is highly variable. The aim of the study is to estimate the prevalence and identify predictors of SIBO in IBS.

METHODS

PubMed, Cochrane Library, and EMBASE through July 2017 were searched to identify studies evaluating the prevalence of SIBO in IBS. The pooled prevalence of SIBO among individuals with IBS and the pooled odds ratio (OR) of SIBO among those with IBS compared with healthy controls were calculated. Predictors of SIBO among IBS patients were also evaluated.

RESULTS

Fifty studies (8398 IBS, 1432 controls) met the inclusion criteria. Overall pooled prevalence of SIBO in IBS was 38% (95% CI 32-44) and was higher among individuals with IBS (OR 4.7, 95% CI 3.1-7.2) compared with controls. The pooled prevalence of SIBO in IBS was higher in studies diagnosed by breath tests (40%, 95% CI 33-46) compared with cultures (19%, 95% CI 8-30). Among those with IBS, female gender (OR 1.5, 95% CI 1.0-2.1), older age (standard mean difference 3.1 years, 95% CI 0.9-5.4), and IBS-diarrhea (OR 1.7, 95% CI 1.3-2.3) compared with other IBS subtypes increased the odds of SIBO; proton pump inhibitor (PPI) use (OR 1.1, 95% CI 0.7-1.7) was not associated with SIBO.

CONCLUSIONS

More than one-third of IBS patients tested positive for SIBO, and the odds of SIBO in IBS were increased by nearly fivefold. The prevalence of SIBO varied according to the diagnostic modality performed. Female gender, older age, and IBS-diarrhea, but not PPI use, were associated with SIBO among individuals with IBS.

Increase in breath hydrogen concentration was correlated with the main pancreatic duct stenosis

BACKGROUND

Hydrogen is produced from unabsorbed carbohydrates in the intestine through degradation and metabolism by hydrogenase of intestinal bacteria. The hydrogen is then partially diffused into blood flow and released and detected in exhaled breath. Pancreatic juice production is decreased in patients with reduced pancreatic exocrine function, including those with pancreatic cancer, thus decreasing digestion and absorption of nutrients including carbohydrates, which may increase undigested carbohydrates in the intestine and increase breath hydrogen concentration (BHC). The aim of this study was to investigate the association between BHC and pancreatic diseases.

METHODS

A retrospective study was designed and 68 patients underwent morning fasting breath hydrogen test. Since there is no clear standard, normal BHC, the median of the measured values from the subjects (9 ppm) was adopted as the standard. The subjects were classified into those with a value exceeding the median (BHC high group: 32 patients) and a value equal to or below the median (BHC low group: 36 patients). Patients characteristics, blood test results and imaging findings characteristic of pancreatic diseases were compared between the groups.

RESULTS

The age was significantly higher (P = 0.010) and the incidences of pancreatic ductal adenocarcinoma and autoimmune pancreatitis were significantly higher (P = 0.018 and P = 0.004, respectively) in the BHC high group. With respect to the blood test items, the Alb level was significantly lower in the BHC high group (P = 0.005). With respect to the characteristic imaging findings of pancreatic diseases, the proportions of patients with pancreatic enlargement, the main pancreatic duct (MPD) stenosis, and the MPD dilatation were significantly higher in the BHC high group (P = 0.022, P < 0.001, and P = 0.002, respectively). On univariate analysis, only the MPD stenosis was extracted as an independent factor (P = 0.014).

CONCLUSION

It was suggested that the fasting BHC is associated with pancreatic diseases causing stenosis of the MPD, including pancreatic cancer (UMIN000020777).

Gut Microbiota-Based Therapies for Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common, heterogeneous disorder characterized by abdominal pain associated with changes in bowel habits. The pathogenesis of IBS is multifactorial and may relate to alterations in the gut microbiota, changes in visceral sensation and motility, and genetic and environmental factors. Administration of systemic antibiotics may increase the risk of IBS by altering gastrointestinal homeostasis. Therapeutic interventions for IBS with diarrhea that are thought to target alterations in the gut microbiota include the nonsystemic antibiotic rifaximin, the medical food serum-derived bovine immunoglobulin, prebiotics, probiotics, and dietary modification. SYN-010 is a modified-release statin formulation that reduces methane production by Methanobrevibacter smithii and is currently in development for the treatment of patients with constipation-predominant IBS. Use of these interventions in the management of patients with IBS may function to restore a healthy gut microbiota and ameliorate symptoms of IBS.

Association Between Small Intestinal Bacterial Overgrowth by Glucose Breath Test and Coronary Artery Disease

BACKGROUND

A possible role of gut bacteria and their metabolic by-products in the development of coronary artery disease (CAD) is suspected. There is a lack of studies evaluating the association of small intestinal bacterial overgrowth (SIBO) with the development of CAD.

AIM

To evaluate the frequency and risk factors for angiography-confirmed CAD in patients with or without SIBO.

METHODS

A total of 1059 patients tested for SIBO using the glucose hydrogen/methane breath test from 2006 to 2014 were evaluated. In total, 160 had coronary artery angiography and were included in the study. SIBO-positive patients were compared to SIBO-negative patients. Demographic, clinical, and laboratory variables and the presence of CAD on coronary angiography were analyzed.

RESULTS

Patients with SIBO had a higher frequency of CAD (78.9 vs. 38.6%, p < 0.001), diabetes mellitus (40.0 vs. 22.9%, p = 0.016), chronic kidney disease (26.7 vs. 12.9%, p = 0.025), use of angiotensin conversion enzyme inhibitor/blocker (45.5 vs. 32.9%, p = 0.008), and statins (75.6 vs. 61.4%, p = 0.004). Patients with SIBO had an increased number of coronary arteries affected compared to SIBO-negative patients (1-vessel disease 67.2 vs. 32.8%, p < 0.001; 2-vessel disease 85.7 vs. 14.3%, p < 0.001; and 3-vessel disease 82.4 vs. 17.6%, p < 0.001, respectively). In the stepwise multivariate logistic regression analysis, SIBO remained an independent risk factor for CAD (odds ratio 7.18, 95% confidence interval 3.09-16.67; p < 0.001).

CONCLUSION

SIBO was found to be associated with CAD and with the number of coronary arteries involved in this study from a single tertiary center. Further studies are necessary to confirm the association of SIBO with CAD. In the presence of risk factors, patients with SIBO may benefit from assessment for CAD.

Hydrogen breath test to detect small intestinal bacterial overgrowth: a prevalence case-control study in autism

The aim of this study is to assess the prevalence of small intestinal bacterial overgrowth (SIBO) by hydrogen breath test in patients with autism spectrum disorders (ASD) with respect to a consistent control group. From 2011 to 2013, 310 children with ASD and 1240 sex- and age-matched typical children were enrolled in this study to undergo glucose breath test. The study participants were considered to exhibit SIBO when an increase in H₂ of ≥20 ppm or CH₄ of ≥10 ppm with respect to the fasting value was observed up to 60 min after the ingestion of glucose. Ninety-six children with autism suffered from SIBO, giving a prevalence rate of SIBO was 31.0% (95% CI 25.8-36.1%). In contrast, 9.3% of the typical children acknowledged SIBO. The difference between groups was statistically significant (P < 0.0001). The median Autism Treatment Evaluation Checklist (ATEC) score in the children with autism and with SIBO was significantly high when compared with the children without autism and without SIBO [98 (IQR, 45-120) vs. 63 (32-94), P < 0.001]. For the autism group, the 6-GI Severity Index (6-GSI) score was found to be strongly and significantly correlated with the total ATEC score (r = 0.639, P < 0.0001). SIBO was significantly associated with worse symptoms of autism, demonstrating that children with SIBO may significantly contribute to symptoms of autism.

Consequences of Small Intestinal Bacterial Overgrowth in Obese Patients Before and After Bariatric Surgery

BACKGROUND AND AIMS

Small intestinal bacterial overgrowth (SIBO) has been described in obese patients. The aim of this study was to prospectively evaluate the prevalence and consequences of SIBO in obese patients before and after bariatric surgery.

PATIENTS AND METHODS

From October 2001 to July 2009, in obese patients referred for bariatric surgery (BMI >40 kg/m² or >35 in association with comorbidities), a glucose hydrogen (H₂) breath test (BT) was performed before and/or after either Roux-en-Y gastric bypass (RYGBP) or adjustable gastric banding (AGB) to assess the presence of SIBO. Weight loss and serum vitamin concentrations were measured after bariatric surgery while a multivitamin supplement was systematically given.

RESULTS

Three hundred seventy-eight (mean ± SD) patients who performed a BT before and/or after surgery were included: before surgery, BT was positive in 15.4 % (55/357). After surgery, BT was positive in 10 % (2/20) of AGB and 40 % (26/65) of RYGBP (p < 0.001 compared to preoperative situation). After RYGBP, patients with positive BT had similar vitamin levels, a lower caloric intake (983 ± 337 vs. 1271 ± 404 kcal/day, p = 0.014) but a significant lower weight loss (29.7 ± 5.6 vs. 37.7 ± 12.9 kg, p = 0.002) and lower percent of total weight loss (25.6 ± 6.0 vs. 29.2 ± 6.9 %, p = 0.044).

CONCLUSION

In this study, SIBO is present in 15 % of obese patients before bariatric surgery. This prevalence does not increase after AGB while it rises up to 40 % of patients after RYGBP and it is associated with lower weight loss.

Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy

The pathogenesis of irritable bowel syndrome (IBS), once thought to be largely psychogenic in origin, is now understood to be multifactorial. One of the reasons for this paradigm shift is the realization that gut dysbiosis, including small intestinal bacterial overgrowth (SIBO), causes IBS symptoms. Between 4% and 78% of patients with IBS and 1% and 40% of controls have SIBO; such wide variations in prevalence might result from population differences, IBS diagnostic criteria, and, most importantly, methods to diagnose SIBO. Although quantitative jejunal aspirate culture is considered the gold standard for the diagnosis of SIBO, noninvasive hydrogen breath tests have been popular. Although the glucose hydrogen breath test is highly specific, its sensitivity is low; in contrast, the early-peak criteria in the lactulose hydrogen breath test are highly nonspecific. Female gender, older age, diarrhea-predominant IBS, bloating and flatulence, proton pump inhibitor and narcotic intake, and low hemoglobin are associated with SIBO among IBS patients. Several therapeutic trials targeting gut microbes using antibiotics and probiotics have further demonstrated that not all symptoms in patients with IBS originate in the brain but rather in the gut, providing support for the micro-organic basis of IBS. A recent proof-of-concept study showing the high frequency of symptom improvement in patients with IBS with SIBO further supports this hypothesis.

Post-infectious IBS, tropical sprue and small intestinal bacterial overgrowth: the missing link

Evidence is emerging that IBS, a hitherto enigmatic disorder thought to be predominantly related to psychological factors, has a microorganic basis in a subset of patients with the disease. Post-infectious IBS (PI-IBS), commonly of the diarrhoea-predominant subtype (defined as new development of IBS following acute infectious diarrhoea), is one such condition known to occur in up to 10-30% individuals after acute gastroenteritis. However, following acute infectious gastroenteritis, patients can also develop post-infectious malabsorption syndrome (PI-MAS), popularly known as tropical sprue. As no study on PI-IBS has rigorously excluded tropical sprue by appropriate investigations, including small intestinal biopsy, the frequency of tropical sprue among patients with PI-IBS is not known. Small intestinal bacterial overgrowth (SIBO) has been suggested to be associated with IBS in general, and in particular diarrhoea-predominant IBS, including PI-IBS. SIBO is also known to be associated with tropical sprue. As both IBS, particularly the subset probably associated with SIBO, and tropical sprue improve with antibiotic treatment, we provide evidence and an explanatory model to support a link among these disorders.

Small intestinal bacterial overgrowth as a cause for irritable bowel syndrome: guilty or not guilty?

PURPOSE OF REVIEW

Small intestinal bacterial overgrowth (SIBO) has been proposed as a cause of irritable bowel syndrome (IBS). However, this relationship has been subject to controversy. This review aims to provide a current perspective on the SIBO-IBS hypothesis.

RECENT FINDINGS

Case-control studies evaluating the prevalence of SIBO in IBS and healthy individuals have shown conflicting results. Moreover, the tests available in routine clinical practice to diagnose SIBO are not valid and lack both sensitivity and specificity. Hence, interpreting the effect of interventions based on these tests is fraught with uncertainty. Furthermore, the SIBO-IBS hypothesis has paved the way to assess antibiotic therapy in nonconstipated IBS, with rifaximin, a nonabsorbable antibiotic, showing modest but significant clinical benefit. However, individuals were not tested for SIBO and the mechanism of action of rifaximin in IBS remains to be elucidated. Preliminary data suggest that rifaximin decreases microbial richness and previous studies have noted antibacterial interventions in IBS to reduce colonic fermentation and improve symptoms. The advent of rapid culture-independent molecular techniques is a promising tool that will seek to clarify and advance our understanding of the gut microbial function.

SUMMARY

The SIBO-IBS hypothesis lacks convincing evidence but remains under scrutiny. The mechanism resulting in symptom improvement after rifaximin treatment in some IBS individuals requires exploration. Novel molecular techniques provide an exciting and challenging opportunity to explore the host-gut microbiota interaction.

Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus

OBJECTIVES

Breath tests (BTs) are important for the diagnosis of carbohydrate maldigestion syndromes and small intestinal bacterial overgrowth (SIBO). However, standardization is lacking regarding indications for testing, test methodology and interpretation of results. A consensus meeting of experts was convened to develop guidelines for clinicians and research.

METHODS

Pre-meeting survey questions encompassing five domains; indications, preparation, performance, interpretation of results, and knowledge gaps, were sent to 17 clinician-scientists, and 10 attended a live meeting. Using an evidence-based approach, 28 statements were finalized and voted on anonymously by a working group of specialists.

RESULTS

Consensus was reached on 26 statements encompassing all five domains. Consensus doses for lactulose, glucose, fructose and lactose BT were 10, 75, 25 and 25 g, respectively. Glucose and lactulose BTs remain the least invasive alternatives to diagnose SIBO. BT is useful in the diagnosis of carbohydrate maldigestion, methane-associated constipation, and evaluation of bloating/gas but not in the assessment of oro-cecal transit. A rise in hydrogen of ≥20 p.p.m. by 90 min during glucose or lactulose BT for SIBO was considered positive. Methane levels ≥10 p.p.m. was considered methane-positive. SIBO should be excluded prior to BT for carbohydrate malabsorption to avoid false positives. A rise in hydrogen of ≥20 p.p.m. from baseline during BT was considered positive for maldigestion.

CONCLUSIONS

BT is a useful, inexpensive, simple and safe diagnostic test in the evaluation of common gastroenterology problems. These consensus statements should help to standardize the indications, preparation, performance and interpretation of BT in clinical practice and research.

Small intestinal bacterial overgrowth is associated with irritable bowel syndrome and is independent of proton pump inhibitor usage

BACKGROUND

Current knowledge suggests that small intestinal overgrowth participates in the pathogenesis of irritable bowel syndrome. It is questionable if this association is modulated by intake of proton pump inhibitors (PPIs).

METHODS

In a prospective study, quantitative cultures of duodenal aspirates were performed for aerobic species in 897 consecutive patients undergoing upper GI tract endoscopy. SIBO was defined as equal to or more than 10(3) cfu/ml. The effect of PPI intake on the relationship between SIBO and IBS was the primary endpoint.

RESULTS

Analysis among patients without any history of PPI intake (n = 713) showed that odds ratio (OR) for IBS in the event of SIBO was 5.63 (3.73-8.51, p < 0.0001); this was 4.16 (1.91-9.06) when analysis was done among patients with history of PPI intake (n = 184, p: 0.498 between patients without and with PPI intake). Multiple logistic regression analysis found that factors independently associated with SIBO were age above or equal to 60 years (OR: 2.36), body mass index more than or equal to 22 kg/m(2) (OR: 0.60), presence of IBS (OR: 6.29), type 2 diabetes mellitus (OR: 1.59) and gastritis (OR: 0.47).

CONCLUSIONS

The association between IBS and SIBO was completely independent from PPI intake. Although gastritis was protective against SIBO, results show that PPI intake cannot prime SIBO.

Small Intestinal Bacterial Overgrowth in Patients with Irritable Bowel Syndrome: Clinical Characteristics, Psychological Factors, and Peripheral Cytokines

Small intestinal bacterial overgrowth (SIBO) has been implicated in the pathogenesis of irritable bowel syndrome (IBS). Psychosocial factors and low-grade colonic mucosal immune activation have been suggested to play important roles in the pathophysiology of IBS. In total, 94 patients with IBS and 13 healthy volunteers underwent a 10 g lactulose hydrogen breath test (HBT) with concurrent ^99mTc scintigraphy. All participants also completed a face-to-face questionnaire survey, including the Hospital Anxiety and Depression Scale, Life Event Stress (LES), and general information. Serum tumour necrosis factor-α, interleukin- (IL-) 6, IL-8, and IL-10 levels were measured. The 89 enrolled patients with IBS and 13 healthy controls had no differences in baseline characteristics. The prevalence of SIBO in patients with IBS was higher than that in healthy controls (39% versus 8%, resp.; p = 0.026). Patients with IBS had higher anxiety, depression, and LES scores, but anxiety, depression, and LES scores were similar between the SIBO-positive and SIBO-negative groups. Psychological disorders were not associated with SIBO in patients with IBS. The serum IL-10 level was significantly lower in SIBO-positive than SIBO-negative patients with IBS.

Hydrogen sulphide in exhaled breath: a potential biomarker for small intestinal bacterial overgrowth in IBS

There is a pressing need to develop a novel early-detection strategy for the precise evolution of small intestinal bacterial overgrowth (SIBO) in irritable bowel syndrome (IBS) patients. The current method based on a hydrogen breath test (HBT) for the detection of SIBO is highly controversial. HBT has many limitations and drawbacks. It often fails to indentify SIBO when IBS individuals have 'non-hydrogen-producing' colonic bacteria. Here, we show that hydrogen sulphide (H2S) in exhaled breath is distinctly altered for diarrhea-predominant IBS individuals with positive and negative SIBO by the activity of intestinal sulphate-reducing bacteria. Subsequently, by analyzing the excretion kinetics of breath H2S, we found a missing link between breath H2S and SIBO when HBT often fails to diagnose SIBO. Moreover, breath H2S can track the precise evolution of SIBO, even after the eradication of bacterial overgrowth. Our findings suggest that the changes in H2S in the bacterial environment may contribute to the pathogenesis of SIBO and the breath H2S as a potential biomarker for non-invasive, rapid and precise assessment of SIBO without the endoscopy-based microbial culture of jejunal aspirates, and thus may open new perspectives into the pathophysiology of SIBO in IBS subjects.

Refining small intestinal bacterial overgrowth diagnosis by means of carbohydrate specificity: a proof-of-concept study

BACKGROUND

Diagnosis of small intestinal bacterial overgrowth (SIBO) remains challenging. This study aimed at proving the diagnostic concept of carbohydrate-specific SIBO (cs-SIBO) using glucose, fructose and sorbitol hydrogen (H2)/methane (CH4) breath testing (HMBT).

METHODS

In this study 125 patients referred to our outpatient clinic for SIBO testing were included. All individuals underwent glucose (50 g), fructose (25 g) and sorbitol (12.5 g) HMBT at 3 consecutive days. Patients with cs-SIBO (i.e. early H2/CH4 peak) were given rifaximin (600 mg/day) in a 10-day treatment. HMBT results were reassessed in a subset of patients 3-6 months after antibiotic therapy. In view of cs-SIBO diagnosis, agreements between HMBT results obtained for different sugars were calculated using Cohen's kappa (κ) with 95% confidence intervals (CIs).

RESULTS

A total of 59 (47.2%) patients presented an early H2/CH4 peak with one or more sugars. Among these, 21 (16.8%), 10 (8.0%) and 7 (5.6%) individuals had a positive HMBT result with either glucose, fructose or sorbitol, respectively. Another 21 (16.8%) patients with a positive glucose HMBT result were also found positive with an early H2/CH4 peak obtained after ingestion of fructose and/or sorbitol. Fair agreement was observed between glucose and fructose (κ = 0.26, p = 0.0018) and between glucose and sorbitol (κ = 0.18, p = 0.0178) HMBT results. Slight agreement was observed between fructose and sorbitol (κ = 0.03, p = 0.6955) HMBT results only. Successful antibiotic therapy with rifaximin could be demonstrated in 26/30 (86.7%) of patients as indicated by normal HMBT results and symptom remission.

CONCLUSIONS

Combined glucose, fructose and sorbitol HMBT has the potential to optimize cs-SIBO diagnosis. Furthermore, the majority of patients with cs-SIBO seem to benefit from rifaximin therapy regardless of its carbohydrate specificity.

Irritable bowel syndrome: new insights into symptom mechanisms and advances in treatment

Despite being one of the most common conditions leading to gastroenterological referral, irritable bowel syndrome (IBS) is poorly understood. However, recent years have seen major advances. These include new understanding of the role of both inflammation and altered microbiota as well as the impact of dietary intolerances as illuminated by magnetic resonance imaging (MRI), which has thrown new light on IBS. This article will review new data on how excessive bile acid secretion mediates diarrhea and evidence from post infectious IBS which has shown how gut inflammation can alter gut microbiota and function. Studies of patients with inflammatory bowel disease (IBD) have also shown that even when inflammation is in remission, the altered enteric nerves and abnormal microbiota can generate IBS-like symptoms. The efficacy of the low FODMAP diet as a treatment for bloating, flatulence, and abdominal discomfort has been demonstrated by randomized controlled trials. MRI studies, which can quantify intestinal volumes, have provided new insights into how FODMAPs cause symptoms. This article will focus on these areas together with recent trials of new agents, which this author believes will alter clinical practice within the foreseeable future.

Molecular assessment of differences in the duodenal microbiome in subjects with irritable bowel syndrome

OBJECTIVE

Breath testing and duodenal culture studies suggest that a significant proportion of irritable bowel syndrome (IBS) patients have small intestinal bacterial overgrowth. In this study, we extended these data through 16S rDNA amplicon sequencing and quantitative PCR (qPCR) analyses of duodenal aspirates from a large cohort of IBS, non-IBS and control subjects.

MATERIALS AND METHODS

Consecutive subjects presenting for esophagogastroduodenoscopy only and healthy controls were recruited. Exclusion criteria included recent antibiotic or probiotic use. Following extensive medical work-up, patients were evaluated for symptoms of IBS. DNAs were isolated from duodenal aspirates obtained during endoscopy. Microbial populations in a subset of IBS subjects and controls were compared by 16S profiling. Duodenal microbes were then quantitated in the entire cohort by qPCR and the results compared with quantitative live culture data.

RESULTS

A total of 258 subjects were recruited (21 healthy, 163 non-healthy non-IBS, and 74 IBS). 16S profiling in five IBS and five control subjects revealed significantly lower microbial diversity in the duodenum in IBS, with significant alterations in 12 genera (false discovery rate < 0.15), including overrepresentation of Escherichia/Shigella (p = 0.005) and Aeromonas (p = 0.051) and underrepresentation of Acinetobacter (p = 0.024), Citrobacter (p = 0.031) and Microvirgula (p = 0.036). qPCR in all 258 subjects confirmed greater levels of Escherichia coli in IBS and also revealed increases in Klebsiella spp, which correlated strongly with quantitative culture data.

CONCLUSIONS

16S rDNA sequencing confirms microbial overgrowth in the small bowel in IBS, with a concomitant reduction in diversity. qPCR supports alterations in specific microbial populations in IBS.

Scintigraphy Demonstrates High Rate of False-positive Results From Glucose Breath Tests for Small Bowel Bacterial Overgrowth

BACKGROUND & AIMS

Breath tests for hydrogen and/or methane are used to detect small bowel bacterial overgrowth (SBBO), but false-positive results can arise from clinical conditions that accelerate small bowel transit and deliver unabsorbed glucose to the colon. We investigated the prevalence of false-positive results from glucose breath tests by also evaluating patients with scintigraphy.

METHODS

In a retrospective study, we reviewed data from glucose breath tests performed with concurrent scintigraphy on 139 patients with suspected SBBO at the Medical College of Wisconsin from January 2003 through July 2013. Results from breath tests were considered abnormal (positive) if there was an increasing curve of hydrogen or methane by >15 parts per million above baseline within 90 minutes. Scintigraphy was used to determine whether this increase occurred before or after the glucose bolus arrived at the cecum. Data from a subset of 45 patients with prior upper gastrointestinal surgery were analyzed separately.

RESULTS

Forty-six of the patients (33%) had abnormal results from breath tests. On the basis of scintigraphy findings, 22 of these patients (48%) had false-positive results, which were caused by colon fermentation of unabsorbed glucose. Colon fermentation caused false-positive results in 65% of patients who had undergone upper gastrointestinal surgery and 13% of patients without prior surgery. Patients with false-positive results caused by colonic fermentation had shorter mean oro-cecal transit times (18 minutes) compared with patients with positive breath-test results because of SBBO (79 minutes) or negative results (86 minutes).

CONCLUSIONS

Almost half of positive results from glucose breath tests are false because of colonic fermentation. All patients with abnormal results from breath tests should be considered for confirmatory repeat breath testing with concurrent scintigraphy to distinguish SBBO from colonic fermentation. Most patients who have undergone upper gastrointestinal surgery have abnormal results from breath tests and should be assessed by using concurrent scintigraphy with the initial breath test.

Irritable Bowel Syndrome May Be Associated with Elevated Alanine Aminotransferase and Metabolic Syndrome

PURPOSE

Recent studies have revealed close relationships between hepatic injury, metabolic pathways, and gut microbiota. The microorganisms in the intestine also cause irritable bowel syndrome (IBS). The aim of this study was to examine whether IBS was associated with elevated hepatic enzyme [alanine aminotransferase (ALT) and aspartate aminotransferase (AST)], gamma-glutamyl transferase (γ-GT) levels, and metabolic syndrome (MS).

MATERIALS AND METHODS

This was a retrospective, cross-sectional, case-control study. The case and control groups comprised subjects who visited our health promotion center for general check-ups from June 2010 to December 2010. Of the 1127 initially screened subjects, 83 had IBS according to the Rome III criteria. The control group consisted of 260 age- and sex-matched subjects without IBS who visited our health promotion center during the same period.

RESULTS

Compared to control subjects, patients with IBS showed significantly higher values of anthropometric parameters (body mass index, waist circumference), liver enzymes, γ-GT, and lipid levels. The prevalences of elevated ALT (16.9% vs. 7.7%; p=0.015) and γ-GT (24.1% vs. 11.5%; p=0.037) levels were significantly higher in patients with IBS than in control subjects. A statistically significant difference was observed in the prevalence of MS between controls and IBS patients (12.7% vs. 32.5%; p<0.001). The relationships between elevated ALT levels, MS, and IBS remained statistically significant after controlling for potential confounding factors.

CONCLUSION

On the basis of our study results, IBS may be an important condition in certain patients with elevated ALT levels and MS.

Specific carbohydrate diet: irritable bowel syndrome patient case study

Purpose

– The purpose of this paper was to investigate the impact of specific carbohydrate restriction (polysaccharides and disaccharides) in the form of the specific carbohydrate diet (SCD) in treating irritable bowel syndrome (IBS).

Design/methodology/approach

– A female patient diagnosed with diarrhea predominant IBS was assigned to the SCD for six months. The diet occurred in phases and was advanced based on the individual’s tolerance level under the guidance of a registered dietitian. Quality of life was measured by a pre- and post-IBS severity score questionnaire. Gastrointestinal symptoms were measured by self-assessment of IBS symptoms using a seven-point Likert-like scale, with −3 = substantially worse to +3 = substantially better. Probiotics were consumed throughout the duration of the study.

Findings

– The quality of life severity score significantly improved from a severity of 315 (with 500 being the most severe) to 15. The initial symptoms from the first day on the diet compared to the total period for bloating, abdominal pain/discomfort, flatulence/wind, diarrhea, bowel urgency, stool consistency, stool frequency, energy levels, incomplete evacuation and abdominal rumbling were improved significantly (p < 0.0005). The SCD diet significantly improved the quality of life and IBS symptoms in a female patient with IBS-diarrhea.

Originality/value

– This study is the first of its kind to evaluate the efficacy of the SCD to treat IBS. The SCD should be considered a therapeutic option to treating IBS after fermentable carbohydrate restriction.

Prevalence of organic disease at colonoscopy in patients with symptoms compatible with irritable bowel syndrome: cross-sectional survey

OBJECTIVE

Guidelines for the management of irritable bowel syndrome (IBS) encourage a positive diagnosis, but some evidence suggests organic disease may be missed unless investigations are performed. We examined yield of colonoscopy in a cohort of secondary care patients meeting criteria for IBS.

MATERIALS AND METHODS

Demographic data, symptoms and findings at colonoscopy were recorded prospectively in consecutive, unselected adults with gastrointestinal (GI) symptoms compatible with IBS according to the Rome III criteria. Prevalence of organic GI disease was compared between those meeting criteria for IBS, according to the presence or absence of co-existent alarm features, and by IBS subtype.

RESULTS

A total of 559 patients met Rome III criteria for IBS, of whom 423 reported ≥1 alarm feature and 136 none. There was a significantly higher prevalence of organic GI disease among those reporting alarm features (117 [27.7%]), compared with those without (21 [15.4%]) (p = 0.002). In the latter group of 136 patients, Crohn's disease was the commonest finding (10 [7.4%] subjects), followed by coeliac disease (4 [2.9%] subjects), and microscopic colitis (3 [2.2%] subjects). Regardless of presence or absence of alarm features, patients with constipation-predominant IBS were less likely to exhibit organic GI disease than those with diarrhea-predominant or mixed IBS (12.7% vs. 32.1% and 23.8%, p = 0.006).

CONCLUSIONS

One in six patients with symptoms compatible with IBS without alarm features in this selected group exhibited organic GI disease following investigation. Assessment of alarm features in a comprehensive history is vital to reduce diagnostic uncertainty that can surround IBS.

Clinical significance of the glucose breath test in patients with inflammatory bowel disease

BACKGROUND AND AIM

Small intestinal bacterial overgrowth which has recently been diagnosed with the glucose breath test is characterized by excessive colonic bacteria in the small bowel, and results in gastrointestinal symptoms that mimic symptoms of inflammatory bowel disease. This study aimed to estimate the positivity of the glucose breath test and investigate its clinical role in inflammatory bowel disease.

METHODS

Patients aged > 18 years with inflammatory bowel disease were enrolled. All patients completed symptom questionnaires. Fecal calprotectin level was measured to evaluate the disease activity. Thirty historical healthy controls were used to determine normal glucose breath test values.

RESULTS

A total of 107 patients, 64 with ulcerative colitis and 43 with Crohn's disease, were included. Twenty-two patients (20.6%) were positive for the glucose breath test (30.2%, Crohn's disease; 14.1%, ulcerative colitis). Positive rate of the glucose breath test was significantly higher in patients with Crohn's disease than in healthy controls (30.2% vs 6.7%, P=0.014). Bloating, flatus, and satiety were higher in glucose breath test-positive patients than glucose breath test-negative patients (P=0.021, 0.014, and 0.049, respectively). The positivity was not correlated with the fecal calprotectin level.

CONCLUSIONS

The positive rate of the glucose breath test was higher in patients with inflammatory bowel disease, especially Crohn's disease than in healthy controls; gastrointestinal symptoms of patients with inflammatory bowel disease were correlated with this positivity. Glucose breath test can be used to manage intestinal symptoms of patients with inflammatory bowel disease.

Small intestinal bacterial overgrowth as an uncommon cause of false positive lactose hydrogen breath test among patients with diarrhea-predominant irritable bowel syndrome in Asia

BACKGROUND AND AIM

It has been reported that small intestinal bacterial overgrowth (SIBO) may lead to false positive diagnoses of lactose malabsorption (LM) in irritable bowel syndrome patients. The aim of this study was to determine the influence of SIBO on lactose hydrogen breath test (HBT) results in these patients.

METHODS

Diarrhea-predominant irritable bowel syndrome patients with abnormal lactose HBTs ingested a test meal containing (99m) Tc and lactose. The location of the test meal and the breath levels of hydrogen were recorded simultaneously by scintigraphic scanning and lactose HBT, respectively. The increase in hydrogen concentration was not considered to be caused by SIBO if ≥ 10% of (99m) Tc accumulated in the cecal region at the time or before of abnormal lactose HBT.

RESULTS

LM was present in 84% (31/37) of irritable bowel syndrome patients. Twenty of these patients agreed to measurement of oro-cecal transit time. Only three patients (15%) with abnormal lactose HBT might have had SIBO. The median oro-cecal transit time between LM and lactose intolerance patients were 75 min and 45 min, respectively (Z=2.545, P=0.011).

CONCLUSIONS

Most of irritable bowel syndrome patients with an abnormal lactose HBT had LM. SIBO had little impact on the interpretation of lactose HBTs. The patients with lactose intolerance had faster small intestinal transit than LM patients.

Small Bowel Bacterial Overgrowth Associated with Persistence of Abdominal Symptoms in Children Treated with a Proton Pump Inhibitor

Small bowel bacterial overgrowth (SBBO) was diagnosed in 22.5% of 40 children treated for 3 months with a proton pump inhibitor (PPI). Compared with those without SBBO, children with SBBO had higher frequency of abdominal pain, bloating, eructation, and flatulence. Patients with gastrointestinal symptoms after PPI treatment should be evaluated for SBBO rather than empirically prolonging PPI therapy.

Autoimmunity Links Vinculin to the Pathophysiology of Chronic Functional Bowel Changes Following Campylobacter jejuni Infection in a Rat Model

BACKGROUND

Acute gastroenteritis can precipitate irritable bowel syndrome (IBS) in humans. Cytolethal distending toxin is common to all pathogens causing gastroenteritis. Its active subunit, CdtB, is associated with post-infectious bowel changes in a rat model of Campylobacter jejuni infection, including small intestinal bacterial overgrowth (SIBO).

AIM

To evaluate the role of host antibodies to CdtB in contributing to post-infectious functional sequelae in this rat model.

METHODS

Ileal tissues from non-IBS human subjects, C. jejuni-infected and control rats were immunostained with antibodies to CdtB, c-Kit, S-100, PGP 9.5 and vinculin. Cytosolic and membrane proteins from mouse enteric neuronal cell lysates were immunoprecipitated with anti-CdtB and analyzed by mass spectrometry. ELISAs were performed on rat cardiac serum using CdtB or vinculin as antigens.

RESULTS

Anti-CdtB antibodies bound to a cytosolic protein in interstitial cells of Cajal (ICC) and myenteric ganglia in C. jejuni-infected and naïve rats and human subjects. Mass spectrometry identified vinculin, confirmed by co-localization and ELISAs. Anti-CdtB antibodies were higher in C. jejuni-infected rats (1.27 ± 0.15) than controls (1.76 ± 0.12) (P < 0.05), and rats that developed SIBO (2.01 ± 0.18) vs. rats that did not (1.44 ± 0.11) (P = 0.019). Vinculin expression levels were reduced in C. jejuni-infected rats (0.058 ± 0.053) versus controls (0.087 ± 0.023) (P = 0.0001), with greater reductions in rats with two C. jejuni infections (P = 0.0001) and rats that developed SIBO (P = 0.001).

CONCLUSIONS

Host anti-CdtB antibodies cross-react with vinculin in ICC and myenteric ganglia, required for normal gut motility. Circulating antibody levels and loss of vinculin expression correlate with number of C. jejuni exposures and SIBO, suggesting that effects on vinculin are important in the effects of C. jejuni infection on the host gut.

Glucose hydrogen breath test for small intestinal bacterial overgrowth in children with abdominal pain-related functional gastrointestinal disorders

OBJECTIVES

A potential link between small intestinal bacterial overgrowth (SIBO) and abdominal pain-related functional gastrointestinal disorders (AP-FGID) has been suggested by symptom similarities and by the reported prevalence of SIBO in children with irritable bowel syndrome (IBS) and functional AP. The aim of this study is to evaluate the prevalence of SIBO using the glucose hydrogen breath test (GHBT), in a cohort of Dutch children with AP-FGID fulfilling the Rome III criteria, and to identify potential predictors.

METHODS

Children ages 6 to 18 years with AP-FGID fulfilling the Rome III criteria were included. All of the children underwent a GHBT. SIBO was diagnosed if the fasting breath hydrogen concentration was ≥20 ppm or an increase in H2 levels of ≥12 ppm above the baseline value was measured after ingestion of glucose. Gastrointestinal symptoms were collected using a standardised AP questionnaire.

RESULTS

A total of 161 Dutch children with AP-FGID were enrolled. Twenty-three patients (14.3%) were diagnosed as having SIBO, as assessed by GHBT; 78% of the children diagnosed as having SIBO had fasting hydrogen levels ≥20 ppm. IBS was significantly more found in children with SIBO compared with children without SIBO (P = 0.001). An altered defecation pattern (ie, change in frequency or form of stool) (P = 0.013), loss of appetite (P = 0.007), and belching (P = 0.023) were significantly more found in children with SIBO compared with those without SIBO.

CONCLUSIONS

SIBO is present in 14.3% of children presenting with AP-FGID. IBS, altered defecation pattern, loss of appetite, and belching were predictors for SIBO in children with AP-FGID.

Small intestinal bacterial overgrowth: duodenal aspiration vs glucose breath test

BACKGROUND

The diagnosis of small intestinal bacterial overgrowth (SIBO) remains challenging. Our aim was to examine the diagnostic yield of duodenal aspiration/culture and glucose breath test (GBT), and effects of gender, race and demographics on prevalence of SIBO.

METHODS

Patients with unexplained gas, bloating and diarrhea and negative endoscopy, imaging and blood tests were prospectively enrolled in two centers in USA. Randomly, within 1 week each patient underwent both duodenal aspiration/culture and GBT. The diagnostic yield of each test and relationship of symptoms, and effects of ethnicity, age, and gender on prevalence of SIBO were assessed and compared.

KEY RESULTS

Duodenal culture was positive in 62/139 (44.6%) subjects and GBT was positive in 38/139 (27.3%) subjects with an overall diagnostic agreement of 65.5%. The sensitivity, specificity, positive and negative predictive value of GBT was 42%, 84%, 68%, and 64%, respectively. Ethnicity or gender did not influence SIBO, but SIBO positive patients were older (p = 0.0018). Symptom patterns were similar except bloating was more prevalent in GBT positive and gas in culture positive subjects.

CONCLUSIONS & INFERENCES

Duodenal aspiration/culture identifies 45% of patients with suspected SIBO. GBT has lower sensitivity but good specificity for detection of SIBO. There were no ethnic or gender differences in the prevalence of SIBO, but patients with SIBO were older. Because GBT is non-invasive, it should be considered first in patients with suspected SIBO.

Small intestinal bacterial overgrowth in patients with chronic pancreatitis

GOALS

To assess the prevalence of small intestinal bacterial overgrowth (SIBO) in chronic pancreatitis (CP), and analyze factors related with SIBO in CP.

BACKGROUND

SIBO is to be considered a factor that worsens symptoms and nutritional status in patients with CP. However, the few studies evaluating the rate of SIBO in CP patients used nonuniform and nonstandardized procedures, and reported a wide range of positivity (0% to 92%). Those studies often investigated CP patients with previous resection surgery (cause of SIBO per se).

STUDY

CP patients and controls evaluated for SIBO by the H2 glucose breath test with a standard protocol. For CP patients, the relationship between test results, abdominal symptoms, and clinical and biochemical variables was analyzed.

RESULTS

A total of 43 CP patients and 43 controls were enrolled. Of the CP patients, 8 had advanced disease (defined by M-ANNHEIM index) and none had undergone previous surgery. The glucose breath test positivity rate was higher in the CP patients than in the controls (21% vs. 14%), albeit without a significant difference (P=0.57). Mean fasting H2 excretion and mean H2 excretion at 120 minutes also had a trend toward higher levels in CP patients. There were no clinical differences between CP patients with or without SIBO, but there were nutritional differences for lower levels of vitamin D and higher levels of folate in these patients with SIBO.

CONCLUSIONS

Our findings suggest that SIBO is not uncommon in uncomplicated CP patients. The lack of a significant difference compared with controls might be due to the study being underpowered. SIBO in CP patients does not seem to be related to peculiar clinical features, but it might affect nutritional status.

Rifaximin for small intestinal bacterial overgrowth in patients without irritable bowel syndrome

BACKGROUND

Rifaximin is a minimally absorbed antibiotic with high luminal activity, used to treat various gastrointestinal diseases. Although rifaximin has been proposed as first line treatment for small intestinal bacterial overgrowth (SIBO), few data are available regarding its efficacy in non-IBS subjects. We aimed to assess the ability of rifaximin to normalize lactulose-H2 breath tests in non-IBS subjects with symptoms suggestive of SIBO.

MATERIALS AND METHODS

Consecutive non-IBS patients presenting with bloating and flatulence were prospectively recruited and submitted to lactulose-H2 breath testing (LBT). Patients who had a positive result were offered rifaximin 1200 mg daily for 10 days. Breath testing was repeated two weeks after treatment completion in all patients in order to assess for response.

RESULTS

A total of 19 patients with a positive result received rifaximin and repeated the breath test (7 (36.8%) males, age 56.5 ± 17.6 years). The mean peak hydrogen excretion was 13.7 ± 2.8 and 10.3 ± 7.3 ppm at baseline and following rifaximin treatment, respectively (t = 1.98, p = 0.06). LBT normalized in 8/19 (42.1%) subjects. No patients reported symptom resolution. No adverse events were reported.

DISCUSSION

Strengths include the study's prospective design. Limitations include the small sample size and open label design.

CONCLUSION

Rifaximin was not effective in normalizing LBT in our cohort of non-IBS subjects with symptoms suggestive of SIBO.

Prevalence, investigational pathways and diagnostic outcomes in differing irritable bowel syndrome subtypes

BACKGROUND

There has been increasing interest in subclassifying irritable bowel syndrome (IBS) to make a positive diagnosis.

AIM

The aim of this study was to assess the population prevalence of differing subtypes, investigational pathways and diagnostic outcomes.

MATERIALS AND METHODS

Data were prospectively collected from three groups between 2005 and 2012. Group 1 [n=1002, 55% female, mean age 39 years (range 16-93 years)] comprised healthy volunteers who were interviewed using the Rome III diagnostic questionnaire. In secondary care, group 2 [n=64, 80% female, mean age 44 years (range 23-79 years)] comprised patients with constipation-predominant IBS (IBS-C) and group 3 [n=333, 66% female, mean age 51 years (range 23-92 years)] comprised patients with diarrhoea-predominant IBS (IBS-D). In groups 2 and 3, demographic data and diagnostic yield of investigations were evaluated as per normal clinical practice.

RESULTS

IBS prevalence in group 1 was 6% (60/1002). IBS-C patients were significantly older than those with IBS-D (mean age 45 vs. 30 years, P=0.027). In groups 2 and 3, patients with IBS-C underwent a total of 56 additional investigations (mean 0.88 per patient), which was significantly lower than the number of investigations undertaken in the IBS-D group of 734 (mean 2.2 per patient, P<0.001). Further investigations in group 3 (IBS-D) identified an alternative diagnosis in 22%, whereas in group 2 (IBS-C) this was 0% (P<0.0001).

CONCLUSION

This is the first study to evaluate the population prevalence of different IBS subtypes within a UK population. Although further investigations in IBS-D patients have led to alternative diagnoses, none were identified in the IBS-C population. The merits of investigating IBS-C patients should be questioned.

Small Intestinal Bacterial Overgrowth is Associated with Intestinal Inflammation in the Irritable Bowel Syndrome

Background and aim

Small intestinal bacterial overgrowth is encountered in bowel disorders, including irritable bowel symptoms. Low degrees of inflammation have been recently reported in the irritable bowel syndrome. We looked for the association between intestinal inflammation and small intestinal bacterial overgrowth in irritable bowel syndrome.

Methods

Small intestinal bacterial overgrowth was assessed by the H2 glucose breath test in 90 consecutive patients with irritable bowel syndrome. A check-up of the oral cavity was carried out before the breath testing. Further on, the patients were classified into two groups, positive and negative, at the breath test. Then they were tested for intestinal inflammation with a fecal test for calprotectin. We used a semiquantitative test for this study. Both groups were compared for the association of intestinal inflammation with small intestinal bacterial overgrowth.

Results

A number of 24/90 (26.7%) patients with irritable bowel syndrome had small intestinal bacterial overgrowth. A positive test for intestinal inflammation was significantly more frequent in patients with irritable bowel syndrome and small intestinal bacterial overgrowth (chi²: p<0.05).

Conclusions

Small intestinal bacterial overgrowth is present in almost one quarter of patients with irritable bowel syndrome. It is significantly associated with intestinal inflammation.

Breath tests and irritable bowel syndrome

Breath tests are non-invasive tests and can detect H₂ and CH₄ gases which are produced by bacterial fermentation of unabsorbed intestinal carbohydrate and are excreted in the breath. These tests are used in the diagnosis of carbohydrate malabsorption, small intestinal bacterial overgrowth, and for measuring the orocecal transit time. Malabsorption of carbohydrates is a key trigger of irritable bowel syndrome (IBS)-type symptoms such as diarrhea and/or constipation, bloating, excess flatulence, headaches and lack of energy. Abdominal bloating is a common nonspecific symptom which can negatively impact quality of life. It may reflect dietary imbalance, such as excess fiber intake, or may be a manifestation of IBS. However, bloating may also represent small intestinal bacterial overgrowth. Patients with persistent symptoms of abdominal bloating and distension despite dietary interventions should be referred for H₂ breath testing to determine the presence or absence of bacterial overgrowth. If bacterial overgrowth is identified, patients are typically treated with antibiotics. Evaluation of IBS generally includes testing of other disorders that cause similar symptoms. Carbohydrate malabsorption (lactose, fructose, sorbitol) can cause abdominal fullness, bloating, nausea, abdominal pain, flatulence, and diarrhea, which are similar to the symptoms of IBS. However, it is unclear if these digestive disorders contribute to or cause the symptoms of IBS. Research studies show that a proper diagnosis and effective dietary intervention significantly reduces the severity and frequency of gastrointestinal symptoms in IBS. Thus, diagnosis of malabsorption of these carbohydrates in IBS using a breath test is very important to guide the clinician in the proper treatment of IBS patients.

Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth

OBJECTIVE

Patients with small intestine bacterial overgrowth (SIBO) have chronic intestinal and extraintestinal symptomatology which adversely affects their quality of life. Present treatment of SIBO is limited to oral antibiotics with variable success. A growing number of patients are interested in using complementary and alternative therapies for their gastrointestinal health. The objective was to determine the remission rate of SIBO using either the antibiotic rifaximin or herbals in a tertiary care referral gastroenterology practice.

DESIGN

One hundred and four patients who tested positive for newly diagnosed SIBO by lactulose breath testing (LBT) were offered either rifaximin 1200 mg daily vs herbal therapy for 4 weeks with repeat LBT post-treatment.

RESULTS

Three hundred ninety-six patients underwent LBT for suspected SIBO, of which 251 (63.4%) were positive 165 underwent treatment and 104 had a follow-up LBT. Of the 37 patients who received herbal therapy, 17 (46%) had a negative follow-up LBT compared to 23/67 (34%) of rifaximin users (P=.24). The odds ratio of having a negative LBT after taking herbal therapy as compared to rifaximin was 1.85 (CI=0.77-4.41, P=.17) once adjusted for age, gender, SIBO risk factors and IBS status. Fourteen of the 44 (31.8%) rifaximin non-responders were offered herbal rescue therapy, with 8 of the 14 (57.1%) having a negative LBT after completing the rescue herbal therapy, while 10 non-responders were offered triple antibiotics with 6 responding (60%, P=.89). Adverse effects were reported among the rifaximin treated arm including 1 case of anaphylaxis, 2 cases of hives, 2 cases of diarrhea and 1 case of Clostridium difficile. Only one case of diarrhea was reported in the herbal therapy arm, which did not reach statistical significance (P=.22).

CONCLUSION

SIBO is widely prevalent in a tertiary referral gastroenterology practice. Herbal therapies are at least as effective as rifaximin for resolution of SIBO by LBT. Herbals also appear to be as effective as triple antibiotic therapy for SIBO rescue therapy for rifaximin non-responders. Further, prospective studies are needed to validate these findings and explore additional alternative therapies in patients with refractory SIBO.

Irritable bowel syndrome and small intestinal bacterial overgrowth: Meaningful association or unnecessary hype

Irritable bowel syndrome (IBS) is a common condition characterized by abdominal pain or discomfort, bloating, and altered stool form and passage. Small intestinal bacterial overgrowth (SIBO) is a condition in which there is overgrowth of bacteria in small bowel in excess of 10⁵ colony forming units per milliliter on culture of the upper gut aspirate. Frequency of SIBO varied from 4%-78% among patients with IBS and from 1%-40% among controls. Higher frequency in some studies might be due to fallacious criteria [post-lactulose breath-hydrogen rise 20 PPM above basal within 90 min (early-peak)]. Glucose hydrogen breath test (GHBT) has a low sensitivity to diagnose SIBO. Hence, studies based on GHBT might have under-estimated frequency of SIBO. Therefore, it is important to analyze these studies carefully to evaluate whether the reported association between IBS and SIBO is over or under-projected. This review evaluates studies on association between SIBO and IBS, discordance between different studies, their strength and weakness including methodological issues and evidence on therapeutic manipulation of gut flora on symptoms of IBS.