Small intestinal bacterial overgrowth in patients with irritable bowel syndrome

Microbial Influences on Irritable Bowel Syndrome

Since the description of postinfection irritable bowel syndrome (IBS), a role for gut microbes in the pathogenesis of IBS has been proposed. Molecular microbiological tools have now been applied to IBS, though data are largely derived from fecal samples with attendant limitations. Metagenomics, metabolomics, and other 'omics facilitate a comprehensive picture of the microbiome and its metabolic activity. Has a microbial signature characteristic of IBS been identified? The answer is no; this should not be a surprise given the heterogeneity of the phenotype and each individual's microbiome profile.

Small Intestinal Bacterial Overgrowth and Pediatric Obesity-A Systematic Review

Background/Objectives: Childhood obesity is a growing global concern linked to metabolic disorders such as nonalcoholic fatty liver disease (NAFLD). Small intestinal bacterial overgrowth (SIBO) may exacerbate these conditions by promoting systemic inflammation and metabolic dysfunction. This review evaluates the prevalence of SIBO in obese children, its association with inflammatory and metabolic markers, and the efficacy of diagnostic and therapeutic strategies. Methods: A systematic search of PubMed, Scopus, and Web of Science (2010-present) was conducted using Boolean operators: ('small intestinal bacterial overgrowth' OR 'SIBO') AND 'prevalence' AND ('low-grade inflammatory markers' OR 'metabolic status') AND 'gut microbiome' AND 'dysbiosis' AND 'obese children'. Results: The data show that SIBO is frequently observed in obese pediatric populations and is associated with gut dysbiosis, impaired nutrient absorption, and reduced production of short-chain fatty acids. These changes contribute to increased intestinal permeability, endotoxemia, and chronic low-grade inflammation. Several microbial taxa have been proposed as biomarkers and therapeutic targets. Diagnostic inconsistencies persist, but treatments such as probiotics, prebiotics, dietary interventions, and selective antibiotics show potential, pending further validation. Conclusions: Early identification and treatment of SIBO with tailored strategies may help reduce metabolic complications and improve outcomes in children with obesity.

An evidence-based update on the diagnosis and management of irritable bowel syndrome

INTRODUCTION

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction affecting 5% of the population. The cardinal symptoms are abdominal pain and altered stool form or frequency.

AREAS COVERED

Diagnosis and management of IBS. We searched the literature for diagnostic accuracy studies, randomized controlled trials, and meta-analyses. A positive diagnosis of IBS, alongside testing to exclude celiac disease, is recommended. Exhaustive investigation has a low yield. Patients should be offered traditional dietary advice. If response is incomplete, specialist dietetic guidance should be considered. Probiotics may be beneficial, but quality of evidence is poor. First-line treatment of constipation is with laxatives, with secretagogues used where these are ineffective. Anti-diarrheal drugs should be used first-line for diarrhea, with second-line drugs including 5-hydroxytryptamine-3 antagonists, eluxadoline, or rifaximin, where available. First-line treatment of abdominal pain should be with antispasmodics, with gut-brain neuromodulators prescribed second-line. Low-dose tricyclic antidepressants, such as amitriptyline, are preferred. Brain-gut behavioral therapies are effective and have evidence for efficacy in patients refractory to standard therapies.

EXPERT OPINION

Despite substantial advances, there remains scope for improvement in terms of both the diagnosis and management of IBS. Reinforcement of positive diagnostic strategies for the condition and novel treatment paradigms are required.

Small Intestinal Bacterial Overgrowth (SIBO), a clinically overdiagnosed entity?

Small intestinal bacterial overgrowth (SIBO) is a clinical entity recognized since ancient times; it represents the consequences of bacterial overgrowth in the small intestine associated with malabsorption. Recently, SIBO as a term has been popularized due to its high prevalence reported in various pathologies since the moment it is indirectly diagnosed with exhaled air tests. In the present article, the results of duodenal/jejunal aspirate culture testing as a reference diagnostic method, as well as the characteristics of the small intestinal microbiota described by culture-dependent and culture-independent techniques in SIBO, and their comparison with exhaled air testing are presented to argue about its overdiagnosis.

Small intestinal bacterial overgrowth in diabetic gastroenteropathy

BACKGROUND

Although diabetic gastroenteropathy (DGE) is associated with small intestinal bacterial overgrowth (SIBO), most studies have evaluated SIBO with a hydrogen breath test, which may be affected by altered transit in DGE. The risk factors for the consequences of SIBO in DGE are poorly understood. We aimed to evaluate the prevalence of, risk factors for, and gastrointestinal symptoms associated with SIBO in patients with DGE.

METHODS

In 75 patients with DGE and dyspepsia, we tested for SIBO (≥105 colony forming units /mL of aerobic and/or anaerobic bacteria in a duodenal aspirate) and assessed gastric emptying (GE) of solids, symptoms during a GE study and during an enteral lipid challenge (300 kcal/2 h), and daily symptoms with a Gastroparesis Cardinal Symptom Index diary for 2 weeks. Symptoms and GE were compared in patients with versus without SIBO.

KEY RESULTS

Of 75 patients, 34 (45%) had SIBO, which was not associated with the use of proton pump inhibitors, daily symptoms, GE, or symptoms during a GE study. During enteral lipid challenge, severe nausea (p = 0.006), fullness (p = 0.02) and bloating (p = 0.009) were each associated with SIBO. Twenty patients (59%) with versus 13 (32%) without SIBO had at least one severe symptom during the lipid challenge (p = 0.006).

CONCLUSIONS & INFERENCES

Among patients with DGE 45% had SIBO, which was associated with symptoms during enteral lipid challenge but not with delayed GE, symptoms during a GE study, or daily symptoms. Perhaps bacterial products and even fatty acids are recognized by and activate mast cells that drive the increased lipid sensitivity in SIBO.

Small Intestinal Bacterial Overgrowth (SIBO) and Twelve Groups of Related Diseases-Current State of Knowledge

The human gut microbiota creates a complex microbial ecosystem, characterized by its high population density, wide diversity, and complex interactions. Any imbalance of the intestinal microbiome, whether qualitative or quantitative, may have serious consequences for human health, including small intestinal bacterial overgrowth (SIBO). SIBO is defined as an increase in the number of bacteria (103-105 CFU/mL), an alteration in the bacterial composition, or both in the small intestine. The PubMed, Science Direct, Web of Science, EMBASE, and Medline databases were searched for studies on SIBO and related diseases. These diseases were divided into 12 groups: (1) gastrointestinal disorders; (2) autoimmune disease; (3) cardiovascular system disease; (4) metabolic disease; (5) endocrine disorders; (6) nephrological disorders; (7) dermatological diseases; (8) neurological diseases (9); developmental disorders; (10) mental disorders; (11) genetic diseases; and (12) gastrointestinal cancer. The purpose of this comprehensive review is to present the current state of knowledge on the relationships between SIBO and these 12 disease groups, taking into account risk factors and the causal context. This review fills the evidence gap on SIBO and presents a biological-medical approach to the problem, clearly showing the groups and diseases having a proven relationship with SIBO, as well as indicating groups within which research should continue to be expanded.

Evaluating the accuracy and reproducibility of ChatGPT-4 in answering patient questions related to small intestinal bacterial overgrowth

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) poses diagnostic and treatment challenges due to its complex management and evolving guidelines. Patients often seek online information related to their health, prompting interest in large language models, like GPT-4, as potential sources of patient education.

AIM

To investigate ChatGPT-4's accuracy and reproducibility in responding to patient questions related to SIBO.

METHODS

A total of 27 patient questions related to SIBO were curated from professional societies, Facebook groups, and Reddit threads. Each question was entered into GPT-4 twice on separate days to examine reproducibility of accuracy on separate occasions. GPT-4 generated responses were independently evaluated for accuracy and reproducibility by two motility fellowship-trained gastroenterologists. A third senior fellowship-trained gastroenterologist resolved disagreements. Accuracy of responses were graded using the scale: (1) Comprehensive; (2) Correct but inadequate; (3) Some correct and some incorrect; or (4) Completely incorrect. Two responses were generated for every question to evaluate reproducibility in accuracy.

RESULTS

In evaluating GPT-4's effectiveness at answering SIBO-related questions, it provided responses with correct information to 18/27 (66.7%) of questions, with 16/27 (59.3%) of responses graded as comprehensive and 2/27 (7.4%) responses graded as correct but inadequate. The model provided responses with incorrect information to 9/27 (33.3%) of questions, with 4/27 (14.8%) of responses graded as completely incorrect and 5/27 (18.5%) of responses graded as mixed correct and incorrect data. Accuracy varied by question category, with questions related to “basic knowledge” achieving the highest proportion of comprehensive responses (90%) and no incorrect responses. On the other hand, the “treatment” related questions yielded the lowest proportion of comprehensive responses (33.3%) and highest percent of completely incorrect responses (33.3%). A total of 77.8% of questions yielded reproducible responses.

CONCLUSION

Though GPT-4 shows promise as a supplementary tool for SIBO-related patient education, the model requires further refinement and validation in subsequent iterations prior to its integration into patient care.

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.

Low prevalence of positive hydrogen breath tests in patients with functional gastrointestinal conditions and hypermobile Ehlers-Danlos syndrome

BACKGROUND

Using hydrogen breath testing (HBT) to diagnose small intestinal bacterial overgrowth (SIBO) remains controversial in patients with functional gastrointestinal (GI) disorders, and unknown in those with hypermobility Ehlers-Danlos syndrome (hEDS). We assessed prevalence of positive HBTs in these groups, evaluated the predictive value of GI symptoms and the potential role of proton pump inhibitors (PPIs) on test results.

METHODS

Sequential patients referred for HBT to a tertiary unit were classified into the following groups: GI maldigestion/malabsorption, GI sensorimotor disorders, hEDS, and functional GI disorders. All underwent standardized HBT, and the yield was assessed against symptoms and PPI use.

KEY RESULTS

A total of 1062 HBTs were performed over 3 years (70% female, mean age 48 ± 16 years). Overall, 7.5% (80/1062) patients had a positive HBT. Prevalence of positive HBT was highest in patients with GI maldigestion/malabsorption (17.9%; DOR 16.16, p < 0.001), GI sensorimotor disorders (15.9%; DOR 8.84, p < 0.001), compared to functional GI disorders (1.6%; DOR 1.0) (p < 0.0001). None of the hEDS patients tested positive for HBT. A positive HBT was independently associated with increased age (DOR 1.03; p < 0.001) and symptoms of diarrhea (DOR 3.95; p < 0.0001). Patients on PPIs tended towards a positive HBT than patients off PPIs (16.1% vs 6.9%; DOR 2.47; p < 0.0001).

CONCLUSIONS & INFERENCES

Less than 2% of patients with functional GI disorders, and none of the patients with hEDS had a positive HBT. Pre-test probability was higher in patients with: GI structural or neurological disorders; use of long-term PPIs and symptoms of diarrhea. These criteria may be helpful in making appropriate therapeutic decisions and avoiding unnecessary hydrogen breath testing.

Associations between irritable bowel syndrome and non-alcoholic fatty liver disease: A systematic review

BACKGROUND

Irritable bowel syndrome (IBS) is associated with obesity and metabolic syndrome. IBS and non-alcoholic fatty liver disease (NAFLD) are highly prevalent entities worldwide and may share similar mechanisms including gut dysbiosis, impaired intestinal mucosal barrier and immune system activation.

AIM

To systematically review their association according to the Preferred Reporting Items for Systemic Review and Meta-analyses guidelines.

METHODS

PubMed, EMBASE and Cochrane Database of Systematic Reviews were searched for relevant papers. Manual searches were also performed.

RESULTS

Six studies were included. Both IBS and NAFLD subjects had significantly more metabolic risk factors like hypertension, obesity, dyslipidaemia and diabetes. Our review showed that 23.2% to 29.4% of NAFLD patients had IBS. IBS was significantly higher in NAFLD patients compared with patients without NAFLD (23.2% vs 12.5%, P < 0.01). A higher proportion of IBS patients had NAFLD (65.8% to 74.0%). IBS patients were three times more likely to have NAFLD compared with non-IBS patients (P < 0.001). Two studies showed a significant correlation between the severity of IBS and NAFLD. The proportion of NAFLD subjects with IBS increased with NAFLD severity.

CONCLUSION

Further prospective studies are warranted to evaluate the relationship and shared pathways between IBS and NAFLD, potentially leading to the development of future therapeutics.

Clinical Presentation of Small Intestinal Bacterial Overgrowth from Aerodigestive Tract Bacteria Versus Colonic-Type Bacteria: A Comparison Study

BACKGROUND

Small Intestinal Bacterial Overgrowth (SIBO) is a heterogenous syndrome from excessive bacteria in the small intestine lumen. It is unknown if differences in type of bacterial overgrowth lead to differences in symptoms.

METHODS

Patients with suspected SIBO were recruited prospectively. Exclusion criteria were probiotics, antibiotics, or bowel prep in preceding 30 days. Clinical characteristics, risk factors, and labs were collected. Proximal jejunal aspiration via upper enteroscopy was performed. Aerodigestive tract (ADT) SIBO was defined as > 10⁵ CFU/mL of oropharyngeal and respiratory bacteria. Colonic-type SIBO was defined as > 10⁴ CFU/mL of distal small bowel and colon bacteria. Aims were to compare symptom profiles, clinical complications, labs, and underlying risk factors between ADT and colonic-type SIBO.

KEY RESULTS

We consented 166 subjects. Aspiration was not obtained in 22 and SIBO was found in 69 (49%) of 144 subjects. Daily abdominal distention trended towards more prevalent in ADT SIBO versus colonic-type SIBO (65.2% vs 39.1%, p = 0.09). Patient symptom scores were similar. Iron deficiency was more prevalent in ADT SIBO (33.3% vs 10.3%, p = 0.04). Subjects with colonic-type SIBO were more likely to have a risk factor for colonic bacteria colonization (60.9% vs 17.4%, p = 0.0006). Subjects with ADT SIBO were more likely to have a risk factor for diminished gastric acid (91.3% vs 67.4%, p = 0.02).

CONCLUSIONS & INFERENCES

We found differences in iron deficiency and underlying risk factors between ADT and colonic-type SIBO. However, distinct clinical profiles remained elusive. Future research is needed to develop validated symptom assessment tools and distinguish cause from correlation.

Antibiotics and Probiotics for Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a disorder of a gut-brain interaction characterised by abdominal pain and a change in stool form or frequency. Current symptom-based definitions and the classification of IBS promote heterogeneity amongst patients, meaning that there may be several different pathophysiological abnormalities leading to similar symptoms. Although our understanding of IBS is incomplete, there are several indicators that the microbiome may be involved in a subset of patients. Techniques including a faecal sample analysis, colonic biopsies, duodenal aspirates or surrogate markers, such as breath testing, have been used to examine the gut microbiota in individuals with IBS. Because of a lack of a clear definition of what constitutes a healthy gut microbiota, and the fact that alterations in gut microbiota have only been shown to be associated with IBS, a causal relationship is yet to be established. We discuss several hypotheses as to how dysbiosis may be responsible for IBS symptoms, as well as potential treatment strategies. We review the current evidence for the use of antibiotics and probiotics to alter the microbiome in an attempt to improve IBS symptoms. Rifaximin, a non-absorbable antibiotic, is the most studied antibiotic and has now been licensed for use in IBS with diarrhoea in the USA, but the drug remains unavailable in many countries for this indication. Current evidence also suggests that certain probiotics, including Lactobacillus plantarum DSM 9843 and Bifidobacterium bifidum MIMBb75, may be efficacious in some patients with IBS. Finally, we describe the future challenges facing us in our attempt to modulate the microbiome to treat IBS.

Prevalence of small intestinal bacterial overgrowth in irritable bowel syndrome (IBS): Correlating H 2 or CH 4 production with severity of IBS

Background and Aim

The prevalence and the role of small intestinal bacterial overgrowth (SIBO) in irritable bowel syndrome (IBS) remain unclear, as the literature provides heterogeneous information on the subject. The aim of this study was to determine the prevalence of SIBO in IBS and to assess the correlation between methane and hydrogen levels measured during breath tests and the severity of IBS.

Method

Two-hundred and forty-seven patients with IBS were prospectively included. A glucose breath test (GBT) measured H₂ and CH₄ production to diagnose SIBO. A test was positive when H₂ values exceeded 12 ppm in the first 90 min and/or when a CH₄ value exceeded 10 ppm at any time. IBS severity (IBS-SSS), quality of life (GIQLI), and anxiety and depression (HAD) were assessed to investigate the correlation with H₂ and CH₄ production.

Results

The prevalence of SIBO in IBS was 36.4% (9.7% with H₂, 26.7% with CH₄). CH₄ levels were significantly higher in the predominantly constipated patients (P = 0.00), while H₂ levels were significantly higher within the diarrheal phenotype (P = 0.01). IBS severity was not correlated with either H₂ levels (r = 0.02; P = 0.84) or CH₄ levels (r = 0.05; P = 0.64). H₂ production was inversely correlated with the quality of life (r = -0.24; P = 0.03) and significantly correlated with the HAD scale (r = 0.22; P = 0.03). The pain and discomfort experienced during GBT was not correlated with methane levels (r = -0.09, P = 0.40), hydrogen levels (r = -0.01, P = 0.93), or sum of both (r = 0.06, P = 0.58), but significantly associated with IBS severity (r = 0.50, P <0.00).

Conclusion

SIBO has a high prevalence in IBS but does not increase its severity. Individual susceptibility to pain may have a greater influence on the severity of IBS.

Association between Gut Dysbiosis and the Occurrence of SIBO, LIBO, SIFO and IMO

Gut microbiota is the aggregate of all microorganisms in the human digestive system. There are 1014 CFU/mL of such microorganisms in the human body, including bacteria, viruses, fungi, archaea and protozoa. The Firmicutes and Bacteroidetes bacteria phyla comprise 90% of the human gut microbiota. The microbiota support the healthy functioning of the human body by helping with digestion (mainly via short-chain fatty acids and amino acids) and producing short-chain fatty acids. In addition, it exhibits many physiological functions, such as forming the intestinal epithelium, intestinal integrity maintenance, the production of vitamins, and protection against pathogens. An altered composition or the number of microorganisms, known as dysbiosis, disrupts the body's homeostasis and can lead to the development of inflammatory bowel disease, irritable bowel syndrome, and metabolic diseases such as diabetes, obesity and allergies. Several types of disruptions to the gut microbiota have been identified: SIBO (Small Intestinal Bacterial Overgrowth), LIBO (Large Intestinal Bacterial Overgrowth), SIFO (Small Intestinal Fungal Overgrowth), and IMO (Intestinal Methanogen Overgrowth). General gastrointestinal problems such as abdominal pain, bloating, gas, diarrhoea and constipation are the main symptoms of dysbiosis. They lead to malabsorption, nutrient deficiencies, anaemia and hypoproteinaemia. Increased lipopolysaccharide (LPS) permeability, stimulating the inflammatory response and resulting in chronic inflammation, has been identified as the leading cause of microbial overgrowth in the gut. The subject literature is extensive but of limited quality. Despite the recent interest in the gut microbiome and its disorders, more clinical research is needed to determine the pathophysiology, effective treatments, and prevention of small and large intestinal microbiota overgrowth. This review was designed to provide an overview of the available literature on intestinal microbial dysbiosis (SIBO, LIBO, SIFO and IMO) and to determine whether it represents a real threat to human health.

Gut Bacterial Dysbiosis in Irritable Bowel Syndrome: a Case-Control Study and a Cross-Cohort Analysis Using Publicly Available Data Sets

Research on the gut microbiota in irritable bowel syndrome (IBS) shows discordant results due to inconsistent study designs or small sample sizes. This study aimed to characterize how gut microbiota in IBS patients differs from that in healthy controls by performing a case-control study and cross- and mega-cohort analysis. Multiple publicly shared data sets were examined by using a unified analytical approach. We performed 16S rRNA gene (V3-4) sequencing and taxonomic profiling of the gut bacterial communities. Fecal samples from children with IBS (n = 19) and age-matched healthy controls (n = 24) were used. Next, we analyzed 10 separate data sets using a unified data-processing and analytical approach. In total, 567 IBS patients and 487 healthy controls were examined. In our data sets, no significant differences existed in stool α-diversity between IBS patients and healthy controls. After combining all the data sets using a unified data-processing method, we found significantly lower α-diversity in IBS patients than in healthy controls. In addition, the relative abundance of 21 bacterial species differed between the IBS patients and healthy participants. Although the causal relationship is uncertain, gut bacterial dysbiosis is associated with IBS. Further functional studies are needed to assess whether the change in gut microorganisms contributes to the development of IBS. IMPORTANCE Research on the gut bacteria in irritable bowel syndrome (IBS) shows discordant results due to inconsistent study designs or small sample sizes. To overcome these issues, we analyzed microbiota of 567 IBS patients and 487 healthy people from 10 shared data sets using a unified method. We demonstrated that gut bacteria are less diverse in IBS patients than in healthy people. In addition, the abundance of 21 bacterial species is different between the two groups. Altered bacterial balance, called dysbiosis, has been reported in several disease states. Although the causal relationship is uncertain, gut bacterial dysbiosis also seems to be associated with IBS.

Associations between postprandial symptoms, hydrogen and methane production, and transit time in irritable bowel syndrome

BACKGROUND

Abnormal oroanal transit time (OATT) and visceral hypersensitivity are key pathophysiological factors in irritable bowel syndrome (IBS). The lactulose nutrient challenge test (LNCT) has been developed to assess the postprandial symptoms and gut microbial fermentation. We aimed to investigate associations between OATT, rectal sensitivity, and LNCT in IBS patients.

METHODS

We included 263 IBS patients from two study cohorts, where the link between pathophysiology and symptoms was investigated. During the LNCT, severity of postprandial symptoms was graded, and breath hydrogen/methane concentrations were measured after ingestion of a combined lactulose nutrient drink every 15 min for 4 h. The patients underwent rectal sensitivity (rectal barostat) and OATT (radiopaque markers) investigations. Comorbid conditions (functional dyspepsia, anxiety, depression, and somatization) were assessed with questionnaires.

KEY RESULTS

After controlling for comorbid conditions, rectal sensitivity was associated with abdominal pain (p < 0.05), and more rapid OATT was associated with higher severity of abdominal discomfort, rumbling, nausea, and urgency (p < 0.05 for all) both pre- and post-prandially. Postprandial nausea, urgency, and abdominal pain changed differently over time depending on OATT (p < 0.05 for all). OATT, but not rectal sensitivity, was associated with hydrogen and methane concentrations (p = 0.002 for both). Trajectories over time of postprandial symptoms and exhaled hydrogen/methane concentrations were correlated with different correlations depending on OATT.

CONCLUSION AND INFERENCES

This study highlights the importance of oroanal transit and hydrogen and methane production in the pathophysiology of IBS and increases our understanding of pathophysiological factors involved in postprandial symptom generation. Treatments targeting oroanal transit and hydrogen and methane production may improve specific postprandial symptoms.

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.

Small Intestinal Bacterial Overgrowth-Pathophysiology and Its Implications for Definition and Management

The concept of small intestinal bacterial overgrowth (SIBO) arose in the context of maldigestion and malabsorption among patients with obvious risk factors that permitted the small bowel to be colonized by potentially injurious colonic microbiota. Such colonization resulted in clinical signs, symptoms, and laboratory abnormalities that were explicable within a coherent pathophysiological framework. Coincident with advances in medical science, diagnostic testing evolved from small bowel culture to breath tests and on to next-generation, culture-independent microbial analytics. The advent and ready availability of breath tests generated a dramatic expansion in both the rate of diagnosis of SIBO and the range of associated gastrointestinal and nongastrointestinal clinical scenarios. However, issues with the specificity of these same breath tests have clouded their interpretation and aroused some skepticism regarding the role of SIBO in this expanded clinical repertoire. Furthermore, the pathophysiological plausibility that underpins SIBO as a cause of maldigestion/malabsorption is lacking in regard to its purported role in irritable bowel syndrome, for example. One hopes that the application of an ever-expanding armamentarium of modern molecular microbiology to the human small intestinal microbiome in both health and disease will ultimately resolve this impasse and provide an objective basis for the diagnosis of SIBO.

Modulating the gut microenvironment as a treatment strategy for irritable bowel syndrome: a narrative review

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction with a complex pathophysiology. Growing evidence suggests that alterations of the gut microenvironment, including microbiota composition and function, may be involved in symptom generation. Therefore, attempts to modulate the gut microenvironment have provided promising results as an indirect approach for IBS management. Antibiotics, probiotics, prebiotics, food and faecal microbiota transplantation are the main strategies for alleviating IBS symptom severity by modulating gut microbiota composition and function (eg. metabolism), gut barrier integrity and immune activity, although with varying efficacy. In this narrative review, we aim to provide an overview of the current approaches targeting the gut microenvironment in order to indirectly manage IBS symptoms.

Organizing and Developing a GI Motility Lab in Community Practice: Challenges and Rewards

PURPOSE OF REVIEW

Neurogastroenterology and motility is a rapidly evolving subspecialty that encompasses over 33% of gastroenterological disorders, and up to 50% of referrals to gastroenterology practice. It includes common problems such as dysphagia, gastroesophageal reflux disease, irritable bowel syndrome, chronic constipation, gastroparesis, functional dyspepsia, gas/bloating, small intestinal bacterial overgrowth, food intolerance and fecal incontinence Standard diagnostic tests such as endoscopy or imaging are normal in these conditions. To define the underlying mechanism(s)/etiology of these disorders, diagnostic motility tests are often required. These are best performed by well-trained personnel in a dedicated motility laboratory. Our purpose is to provide an up-to-date overview on how to organize and develop a motility laboratory based on our collective experiences in setting up such facilities in academia and community practice.

RECENT FINDINGS

A lack of knowledge, training and facilities for providing diagnostic motility tests has led to suboptimal patient care. A motility laboratory is the hub for diagnostic and therapeutic motility procedures. Common procedures include esophageal function tests such as esophageal manometry and pH monitoring, anorectal function tests suchlike anorectal manometry, neurophysiology and balloon expulsion, dysbiosis and food intolerance tests such as hydrogen/methane breath tests, and gastrointestinal transit assessment. These tests provide an accurate diagnosis and guide clinical management including use of medications, biofeedback therapy, neuromodulation, behavioral therapies, evidence-based dietary interventions and endoscopic or surgical procedures. Further, there have been recent developments in billing and coding of motility procedures and training requirements that are not well known. This review provides a stepwise approach on how to set-up a motility laboratory in the community or academic practice and includes the rationale, infrastructure, staffing needs, commonly performed motility tests and their clinical utility, billing and coding strategies, training needs and economic considerations for setting up this service.

Expression of TRP Channels in Colonic Mucosa of IBS-D Patients and Its Correlation with the Severity of the Disease

Aim

Lots of researches have endeavored to elucidate the pathogenetic mechanism of visceral hypersensitivity in order to guide the therapy of diarrhea predominant-irritable bowel syndrome (IBS-D). Transient receptor potential (TRP) channels and their role in visceral nociception have been vastly investigated. We investigated the expression of TRP channels in IBS-D colonic biopsies and its correlation with the severity of the disease.

Methods

Sigmoid biopsies were obtained from 34 IBS-D patients and 28 healthy controls (HCs). IBS-D was diagnosed according to Rome IV criteria. Their clinical parameters were assessed through questionnaires. Expression of TRPV1, TRPV4, TRPA1, TRPM2, and TRPM8 was evaluated with immunohistology staining.

Results

Expression levels of TRPV1, TRPV4, and TRPA1 in the colonic mucosa of IBS-D patients were significantly higher than those in HCs (p < 0.05), while there was no obvious difference of TRPM2 and TRPM8 expression between IBS-D patients and HCs. In addition, the expression levels of TRPV1 and TRPA1, but TRPV4, in the colonic mucosa correlated positively with the severity of diseases (r = 0.6303 and 0.4506, respectively, p < 0.05).

Conclusions

Expression of TRPV1, TRPA1, and TRPV4 in the colonic mucosa was enhanced in IBS-D patients compared with HCs with the former two correlated with the severity of the disease. TRP channels might be promising biomarkers in the diagnosis and estimate of the severity in IBS-D.

Colonic mucosal eosinophilia and immunohistochemical expression of COX-2 and NF-kB in patients with irritable bowel syndrome

BACKGROUND

There is growing evidence that eosinophilic infiltration can release mediators which are harmful to the intestinal epithelium in patients with irritable bowel syndrome (IBS). Although cyclooxygenase 2 (COX-2) and nuclear factor-kappa beta (NF-kB) expression had been previously reported to increase in many inflammatory conditions, there is a paucity in data investigating their expressions in IBS. Our aim was to evaluate colonic mucosal eosinophilia and immunohistochemical expression of COX-2 and NF-kB in patients with irritable bowel syndrome.

METHODS

A total of 80 patients who met the inclusion criteria of IBS based on Rome IV symptoms questionnaire were subjected to abdominal ultrasound, laboratory investigations, serum immunoglobulin E (IgE) level assessment and colonoscopic examination. Immunohistochemistry was performed to detect COX-2 and NF-kB expression in colonic biopsies obtained from IBS patients.

RESULTS

Histopathological examination showed that 60 colonic biopsy specimens (75%) showed few mixed inflammatory cells ≤3 cells/ HPF, 12 biopsy specimens (15%) showed eosinophilic infiltration ≥25 eosinophils/HPF and 8 biopsy specimens (10%) showed severe lymphocytic infiltration and aggregation. Colonic eosinophilic infiltrate was significantly higher among patients presented with IBS-D subtype. Serum IgE was significantly higher among patients with colonic eosinophilic infiltrate than the others. In IBS-D patients, colonic mucosa showed positive expression of COX-2 and NF-kB in 52.1% and 81.25% of cases, respectively.

CONCLUSION

Patients with IBS -particularly IBS-D subtype- should undergo colonoscopy and biopsy to exclude underlying inflammatory pathology. Moreover, patients with positive COX-2 and NF-kB need further evaluation and follow-up.

Asian-Pacific consensus on small intestinal bacterial overgrowth in gastrointestinal disorders: An initiative of the Indian Neurogastroenterology and Motility Association

In the clinical setting, small intestinal bacterial overgrowth (SIBO) is a frequent, but under-diagnosed entity. SIBO is linked to various gastrointestinal (GI) and non-GI disorders with potentially significant morbidity. The optimal management of SIBO is undefined while there is a lack of published consensus guidelines. Against this background, under the auspices of the Indian Neurogastroenterology and Motility Association (INMA), formerly known as the Indian Motility and Functional Diseases Association (IMFDA), experts from the Asian-Pacific region with extensive research and clinical experience in the field of gut dysbiosis including SIBO developed this evidence-based practice guideline for the management of SIBO utilizing a modified Delphi process based upon 37 consensus statements, involving an electronic voting process as well as face-to-face meetings and review of relevant supporting literature. These statements include 6 statements on definition and epidemiology; 11 on etiopathogenesis and pathophysiology; 5 on clinical manifestations, differential diagnosis, and predictors; and 15 on investigations and treatment. When the proportion of those who voted either to accept completely or with minor reservations was 80% or higher, the statement was regarded as accepted. The members of the consensus team consider that this guideline would be valuable to inform clinical practice, teaching, and research on SIBO in the Asian-Pacific region as well as in other countries.

Adding a liquid test meal to a standardized lactulose hydrogen breath test significantly influences abdominal symptom generation and hydrogen values

OBJECTIVE

While single sugar tests are controversially discussed, combination tests with meals are gaining more attention. The aim of this study was to analyze the impact of adding a test meal to lactulose hydrogen breath tests (LHBT) on hydrogen values and abdominal symptoms in patients with functional gastrointestinal disorders (FGIDs).

METHODS

Data of 81 FGID patients between 2014-2018 were analyzed. Patients underwent LHBT with 30 g lactulose + 300 mL water and a nutrient challenge test (NCT) including 400 mL liquid test meal + 30 g lactulose. To statistically assess the effect of a test meal on abdominal symptoms and H2, mixed-effect models were used.

RESULTS

Adding a test meal to LHBT showed a significant increase in nausea [odds ratio (OR) 1.4; 95% confidence interval (CI), 1.1-1.7], decrease in abdominal pain (OR 0.7; 95% CI, 0.6-0.9), borborygmi (OR 0.5; 95% CI, 0.4-0.6), diarrhea (OR 0.4; 95% CI, 0.3-0.6), and H2 production (estimate -5.3, SE 0.7, P < 0.001). The effect on bloating was only significant in functional dyspepsia, irritable bowel syndrome-functional dyspepsia mixed type and functional abdominal pain/bloating (OR 0.1; 95% CI, 0.0-0.2; OR 1.7; 95% CI, 1.2-2.3 resp OR 4.4; 95% CI, 1.8-10.6).

CONCLUSIONS

Significant effects on abdominal symptoms and H2 production by adding a test meal to LHBT in FGID patients are shown. Increased occurrence of nausea may be caused by gastric/duodenal hypersensitivity; decreased H2, diarrhea and borborygmi by slower and more physiologic gastric emptying resulting in later arrival of the test substance in the bowel. We recommend NCTs instead of LHBT to more physiologically represent FGID patients' meal-induced burden.

Review article: Diagnosis and investigation of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common disorder of gut-brain interaction. It is defined by the Rome criteria as the presence of abdominal pain, related to defaecation, associated with a change in stool form and/or frequency. The approach to diagnosis and investigation of suspected IBS varies between clinicians and, due in part to the uncertainty that can surround the diagnosis, many still consider it to be a diagnosis of exclusion. However, exhaustive investigation is both unnecessary and costly, and may also be counterproductive. Instead, physicians should aim to make a positive diagnosis, based on their clinical assessment of symptoms, and limit their use of investigations. The yield of routine blood tests in suspected IBS is low overall, but normal inflammatory markers may be reassuring. All patients should have serological testing for coeliac disease, irrespective of their predominant stool form. Routine testing of stool microbiology or faecal elastase is unnecessary; however, all patients with diarrhoea aged <45 should have a faecal calprotectin or a similar marker measured which, if positive, should lead to colonoscopy to exclude possible inflammatory bowel disease. Colonoscopy should also be undertaken in any patient reporting alarm symptoms suggestive of colorectal cancer, and in those whose presentation raises suspicion for microscopic colitis. Testing for bile acid diarrhoea should be considered for patients with IBS with diarrhoea where available. Hydrogen breath tests for lactose malabsorption or small intestinal bacterial overgrowth have no role in the routine assessment of suspected IBS. Adopting a standardised approach to the diagnosis and investigation of IBS will help to promote high-quality and high-value care for patients overall.

Targeting the Gut Microbiota to Relieve the Symptoms of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common, chronic, functional disorder with a large impact on world population. Its pathophysiology is not completely revealed; however, it is certain that dysregulation of the bidirectional communications between the central nervous system (CNS) and the gut leads to motility disturbances, visceral hypersensitivity, and altered CNS processing characterized by differences in brain structure, connectivity and functional responsiveness. Emerging evidence suggests that gut microbiota exerts a marked influence on the host during health and disease. Gut microbiome disturbances can be also important for development of IBS symptoms and its modulation efficiently contributes to the therapy. In this work, we review the current knowledge about the IBS therapy, the role of gut microbiota in pathogenesis of IBS, and we discuss that its targeting may have significant impact on the effectiveness of IBS therapy.

Progress in understanding of relationship between gut microbiota and gastrointestinal motility

Gastrointestinal motility disorders are a group of common clinical disorders in which abnormal gastrointestinal motility is the major pathogenesis, including irritable bowel syndrome, functional dyspepsia, and diabetic gastroparesis. With the rapid development of microbial sequencing technology in the past 10 years, the understanding of the gut microbiota has greatly improved, and it is generally found that patients with gastrointestinal motility diseases have gut microbiota disorders. Some progress has been made on the correlation between gut microbiota and gastrointestinal motility. This review aims to elucidate the relationship between gut microbiota and gastrointestinal motility and the mechanism of their interaction.

Emerging Role of the Gut Microbiome in Irritable Bowel Syndrome

Advances in bioinformatics have facilitated investigation of the role of gut microbiota in patients with irritable bowel syndrome (IBS). This article describes the evidence from epidemiologic and clinical observational studies highlighting the link between IBS and gut microbiome by investigating postinfection IBS, small intestinal bacterial overgrowth, and microbial dysbiosis. It highlights the effects of gut microbiota on mechanisms implicated in the pathophysiology of IBS, including gut-brain axis, visceral hypersensitivity, motility, epithelial barrier, and immune activation. In addition, it summarizes the current evidence on microbiome-guided therapies in IBS, including probiotics, antibiotics, diet, and fecal microbiota transplant.

A Promising Approach: Artificial Intelligence Applied to Small Intestinal Bacterial Overgrowth (SIBO) Diagnosis Using Cluster Analysis

Small intestinal bacterial overgrowth (SIBO) is characterized by abnormal and excessive amounts of bacteria in the small intestine. Since symptoms and lab tests are non-specific, the diagnosis of SIBO is highly dependent on breath testing. There is a lack of a universally accepted cut-off point for breath testing to diagnose SIBO, and the dilemma of defining "SIBO patients" has made it more difficult to explore the gold standard for SIBO diagnosis. How to validate the gold standard for breath testing without defining "SIBO patients" has become an imperious demand in clinic. Breath-testing datasets from 1071 patients were collected from Xiangya Hospital in the past 3 years and analyzed with an artificial intelligence method using cluster analysis. K-means and DBSCAN algorithms were applied to the dataset after the clustering tendency was confirmed with Hopkins Statistic. Satisfying the clustering effect was evaluated with a Silhouette score, and patterns of each group were described. Advantages of artificial intelligence application in adaptive breath-testing diagnosis criteria with SIBO were discussed from the aspects of high dimensional analysis, and data-driven and regional specific dietary influence. This research work implied a promising application of artificial intelligence for SIBO diagnosis, which would benefit clinical practice and scientific research.

Fecal microbiome differs between patients with systemic sclerosis with and without small intestinal bacterial overgrowth

Introduction:

Gastrointestinal manifestations of systemic sclerosis affect up to 90% of patients, with symptoms including diarrhea and constipation. Small intestinal bacterial overgrowth is a condition associated with increased numbers of pathogenic bacteria in the small bowel. While currently unknown, it has been suggested that dysregulation of the fecal microbiota may play a role in the development of systemic sclerosis and small intestinal bacterial overgrowth.

Objectives:

Our study aimed to describe the fecal microbiota of patients with systemic sclerosis and compare it between those with and without a diagnosis of small intestinal bacterial overgrowth. We also compared the fecal microbiota of systemic sclerosis patients with that of healthy controls to understand the association between particular bacterial taxa and clinical gastrointestinal manifestations of systemic sclerosis.

Methods:

A total of 29 patients with systemic sclerosis underwent breath testing to assess for small intestinal bacterial overgrowth, provided stool samples to determine taxonomic assignments, and completed the University of California Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract 2.0, which details symptoms and quality-of-life factors. Stool samples were compared between systemic sclerosis patients with and without small intestinal bacterial overgrowth, and between patients with systemic sclerosis and a healthy control cohort (n = 20), aged 18–80 years.

Results:

Fecal microbiome analyses demonstrated differences between systemic sclerosis patients with and without small intestinal bacterial overgrowth and differences in the diversity of species between healthy controls and patients with systemic sclerosis. Trends were also observed in anticentromere antibody systemic sclerosis patients, including higher Alistipies indistincus spp. levels associated with increased methane levels of breath gas testing and higher Slakia spp. levels associated with increased rates of fecal soiling.

Conclusions:

Our results suggest that changes to the fecal microbiome occur in patients with small intestinal bacterial overgrowth and systemic sclerosis when compared to healthy controls. As a cross-sectional study, the potential pathophysiologic role of an altered microbiome in the development of systemic sclerosis was not considered and hence needs to be further investigated.

Clinical guidelines “Chronic diarrhea in adults”

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Comparative effectiveness of 5-hydroxytryptamine 3 receptor antagonists in irritable bowel syndrome: a network meta-analysis of randomized controlled studies

BACKGROUND

There is evidence demonstrating the beneficial effects of 5-hydroxytryptamine 3 receptor antagonists (5-HT3) for the treatment of non-constipated irritable bowel syndrome (NC-IBS). We aimed to determine the comparative effectiveness of 5-HT3 antagonists in NC-IBS, as evidenced by the results of a network meta-analysis (NWM) of published relevant randomized controlled trials (RCTs).

METHODS

We searched the PubMed/Medline, EMBASE, and Cochrane Library databases for relevant RCTs through September 2020 and data from each selected RCT were extracted. A Bayesian NWM was then performed to investigate the efficacy of 5-HT3 antagonists and to explore the effectiveness rank order in treating NC-IBS patients.

RESULTS

Twenty-one eligible RCTs were identified and entered into this NWM. They included a total of 10,421 NC-IBS patients, randomized to alosetron, cilansetron, ondansetron, ramosetron, placebo, and mebeverine. The cumulative ranking probability for each intervention at the end of treatment period, was evaluated by means of surfaces under cumulative ranking (SUCRA) values. These results showed that alosetron had the best performance for global symptom improvement (SUCRA 0.82), cilansetron showed the best performance (SUCRA 0.90) for abdominal pain/discomfort improvement, while ondansetron (SUCRA 0.98) was by far the best choice concerning bowel habits/consistency improvement. The control regimens (mebeverine and placebo) represented the least efficacious interventions.

CONCLUSIONS

This NWM showed that 5-HT3 receptor antagonists performed better in comparison to control drugs. Consequently, this class of drugs may play an important role in improving the debilitating symptoms in NC-IBS patients, in particular those with diarrhea.

British Society of Gastroenterology guidelines on the management of irritable bowel syndrome

Irritable bowel syndrome (IBS) remains one of the most common gastrointestinal disorders seen by clinicians in both primary and secondary care. Since publication of the last British Society of Gastroenterology (BSG) guideline in 2007, substantial advances have been made in understanding its complex pathophysiology, resulting in its re-classification as a disorder of gut-brain interaction, rather than a functional gastrointestinal disorder. Moreover, there has been a considerable amount of new evidence published concerning the diagnosis, investigation and management of IBS. The primary aim of this guideline, commissioned by the BSG, is to review and summarise the current evidence to inform and guide clinical practice, by providing a practical framework for evidence-based management of patients. One of the strengths of this guideline is that the recommendations for treatment are based on evidence derived from a comprehensive search of the medical literature, which was used to inform an update of a series of trial-based and network meta-analyses assessing the efficacy of dietary, pharmacological and psychological therapies in treating IBS. Specific recommendations have been made according to the Grading of Recommendations Assessment, Development and Evaluation system, summarising both the strength of the recommendations and the overall quality of evidence. Finally, this guideline identifies novel treatments that are in development, as well as highlighting areas of unmet need for future research.

Hydrogen and methane breath test results are negatively associated with IBS and may reflect transit time in post-surgical patients

BACKGROUND

Contention surrounds hydrogen and methane breath tests as putative measures of small intestinal bacterial overgrowth. We aimed to explore the clinical characteristics associated with positive and negative results to help clarify their role.

METHODS

525 glucose hydrogen/methane breath tests completed over 3 years were analyzed to look for positively and negatively associated predictive factors. Characteristics such as height and weight and underlying medical conditions, medications, and surgical history were collated.

KEY RESULTS

There were 85 and 42 positive hydrogen and methane tests, respectively. Patients with irritable bowel syndrome (IBS) (HR = 0.17, p = 0.004) and those with a higher body mass index (HR = 0.93, p = 0.004) were significantly less likely to have a positive test. Patients who underwent the test post-surgically were significantly more likely to have a positive test (HR = 2.76, p = 0.001). A sub-analysis of post-surgical patients by type and region of surgical resection demonstrated that none were statistically more likely than the next to have a positive test. However, for the surgical group as a whole the number of motility-depressing drugs taken (such as opioids) was associated with a significantly decreased likelihood of a positive test (HR = 0.752, p = 0.045).

CONCLUSION

Our data suggest that patients with a diagnosis of IBS are statistically less likely to have a positive test and it is of limited utility in this group. Post-surgical patients are more likely to have a positive test, possibly secondary to fast transit rather than bacterial overgrowth, as suggested by a significantly negative association with motility-suppressing drugs in this sub-group.

Effects of Medium Chain Fatty Acids on Intestinal Health of Monogastric Animals

Medium-chain fatty acids (MCFAs) are the main form of Medium Chain Triglycerides (MCTs) utilized by monogastric animals. MCFAs can be directly absorbed and supply rapid energy to promote the renewal and repair of intestinal epithelial cells, maintain the integrity of intestinal mucosal barrier function, and reduce inflammation and stress. In our review, we pay more attention to the role of MCFAs on intestinal microbiota and mucosa immunity to explore MCFA's positive effect. It was found that MCFAs and their esterified forms can decrease pathogens while increasing probiotics. In addition, being recognized via specific receptors, MCFAs are capable of alleviating inflammation to a certain extent by regulating inflammation and immune-related pathways. MCFAs may also have a certain value to relieve intestinal allergy and inflammatory bowel disease (IBD). Unknown mechanism of various MCFA characteristics still causes dilemmas in the application, thus MCFAs are used generally in limited dosages and combined with short-chain organic acids (SOAs) to attain ideal results. We hope that further studies will provide guidance for the practical use of MCFAs in animal feed.

Treating the Metabolic Syndrome by Fecal Transplantation-Current Status

The intestinal microbiome (IM) is important for normal gastrointestinal (GI) and other organ systems' functioning. An alteration in the normal IM, dysbiosis, and changes in intestinal motility result in microorganisms' overgrowth and an alteration in intestinal permeability. The gut-brain axis is also of importance in the irritable bowel syndrome (IBS) and associated bowel overgrowth. Secondary to the epidemic of obesity, the metabolic syndrome has become a major health problem. Disturbances in the fecal microbiome are associated with the metabolic syndrome. Metabolic-associated fatty liver disease (MAFLD) is now the current terminology for non-alcoholic fatty liver disease. IM alteration by fecal transplantation is an approved treatment method for recurrent Clostridioides difficile infection. Initially performed by either duodenal infusion or colonoscopy, it is now easily performed by the administration of capsules containing stools. We discuss the intestinal microbiome-its composition, as well as the qualitative changes of microbiome composition leading to inflammation. In addition, we discuss the evidence of the effect of fecal transplantation on the metabolic syndrome and MAFLD, as well as its clinical indications.

Lactose Sensitivity and Lactose Malabsorption: The 2 Faces of Lactose Intolerance

Background/Aims

Self-reported lactose intolerance (LI) is frequent in patients with functional bowel disorders (FBD) that could be interpreted as irritable bowel syndrome (IBS). The present study aims to characterize the responses of patients with FBD, without small intestinal bacterial overgrowth (SIBO), and LI, in terms of lactose malabsorption (LM) and lactose sensitivity (LS) according to psychological and clinical features.

Methods

One hundred and fifty-eight consecutive FBD outpatients with LI, and no SIBO, were classified according to the Rome III questionnaire and filled Beck Depression Inventory, and State and Trait Anxiety questionnaires. They underwent a lactose tolerance test in which glycemia during 60 minutes and digestive symptoms for 3 hours were recorded.

Results

Abnormal lactose tolerance tests were found in 110 patients (70%), 44 (28%) with LM, 96 (61%) with LS, and 30 (19%) having both LM and LS. LM patients had a higher frequency of functional diarrhea (P = 0.040) and a lower frequency of dysphagia (P = 0.031). LS patients had a higher depression score (P = 0.007), higher frequency of globus (P = 0.042), irritable bowel syndrome (IBS) (P = 0.027) and mixed IBS (P = 0.049), and lower frequency of abdominal pain (P = 0.040). LS was significantly associated with a higher depression score (P = 0.002), and a higher frequency of globus (P = 0.046).

Conclusions

Thirty percent of LI patients have normal lactose absorption and normal LS. In the other 70% of patients, LI could be associated with LM and/or LS.

Irritable Bowel and Bacterial Overgrowth Syndromes: a Bacterial Link Hypothesis of Functional Disease

Aim. Assessment of the irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth syndrome (SIBO) interlinkage.

Key points. SIBO may represent a "peripheral" mechanism of IBS, aside to nonspecific inflammation, increased epithelial permeability and local immune system activation. In various assays, the SIBO rate in IBS patients was 4-46% vs. 0-13% in an intact cohort. A limited diagnosability of SIBO obscures the SIBO-IBS causal interplay. Impaired motility in IBS may predispose to the SIBO development. Proinflammatory cytokines and mediators in SIBO, in turn, provoke visceral hypersensitivity and intense motility, the key IBS factors. Both conditions relate to qualitative and quantitative changes in microbiota, which warrants the application of probiotic Lactobacillus and Bifidobacterium strains.

Conclusion. Further research into the SIBO-IBS interface is required for developing optimal probiotic-based therapies.

[Functional Exams in the gastroenterology - new developments and tips for the common practice]

The functional gastrointestinal disorders (FGIDs) have a high prevalence and are associated with high healthcare costs. The diagnosis of these diseases could be difficult and require func-tional tests such as high-resolution manometry (HRM) of the esophagus, anorectal manometry and H2-Breathtests. Due to the COVID-19 Pandemic and the fear of infections there was a marked reduction in the number of performed exams in the last months - nevertheless some exams are necessary, in order to exclude or to diagnose important and dangerous diseases like Achalasia. Goal of this article is to present some new and relevant developments in the field. The HRM of the esophagus is the diagnostic standard for Achalasia, a rare clinical condi-tion associated to dysphagia - new European guidelines suggests a safe strategy in perform-ing the pneumatic dilatation.The intestinal methanogen overgrowth (IMO) is a clinical condition caused by a high production of methane in the small intestine due to overgrowth of Methanobrevibacter smithii, this condition could be in some patients associated with irritable bowel syndrome.

Diagnosis and Treatment of Irritable Bowel Syndrome: A Review

IMPORTANCE

The prevalence of irritable bowel syndrome (IBS) in the United States is between 7% and 16%, most common in women and young people, with annual direct costs estimated at more than $1 billion dollars in the United States. Traditionally, the diagnosis of IBS has been based on the positive identification of symptoms that correlate with several different syndromes associated with disorders such as IBS diarrhea, IBS constipation, functional diarrhea, functional constipation, chronic functional abdominal pain, or bloating. Several peripheral and central mechanisms initiate gastrointestinal motor and sensory dysfunctions leading to IBS symptoms. Those dysfunctions may require evaluation in patients whose symptoms do not respond to first-line treatments.

OBSERVATIONS

Validation studies of consensus symptom-based criteria have identified deficiencies that favor a simpler identification of the predominant symptoms of abdominal pain, bowel dysfunction, and bloating and exclusion of alarm symptoms such as unintentional weight loss, rectal bleeding, or recent change in bowel function. Symptom-based diagnosis of IBS is enhanced with additional history for symptoms of somatoform and psychological disorders and alarm symptoms, physical examination including digital rectal examination, and screening tests to exclude organic disease (by measuring hemoglobin and C-reactive protein concentrations). The initial treatment plan should include patient education, reassurance, and first-line treatments such as fiber and osmotic laxatives for constipation, opioids for diarrhea, antispasmodics for pain and for management of associated psychological disorders. For patients who do not respond to those IBS treatments, testing for specific functional disorders may be required in a minority of patients with IBS. These disorders include rectal evacuation disorder, abnormal colonic transit, and bile acid diarrhea. Their identification is followed by individualized treatment, such as pelvic floor retraining for rectal evacuation disorders, sequestrants for bile acid diarrhea, and secretory agents for constipation, although there is only limited evidence that this individualized management approach is effective.

CONCLUSIONS AND RELEVANCE

Advances in the identification of specific dysfunctions as causes of individual symptoms in the "IBS spectrum" leads to the potential to enhance the diagnosis and management of symptoms for the majority of patients for whom first-line therapies of IBS and management of comorbid psychological disorders are insufficient.

Rosacea, Germs, and Bowels: A Review on Gastrointestinal Comorbidities and Gut-Skin Axis of Rosacea

Rosacea is a chronic inflammatory disease with complicated pathophysiology that involves genetic and environmental elements and dysregulation of innate and adaptive immunity, neurovascular responses, microbiome colonization or infection, resulting in recurrent inflammation. Rosacea has been reported associated with various gastrointestinal diseases including inflammatory bowel disease, celiac disease, irritable bowel syndrome, gastroesophageal reflux disease, Helicobacter pylori (HP) infection, and small intestine bacterial overgrowth (SIBO). The link may involve common predisposing genetic, microbiota, and immunological factors, comprising the theory of the gut–skin axis. Although the evidence is still controversial, interestingly, medications for eradicating SIBO and HP provided an effective and prolonged therapeutic response in rosacea, and conventional therapy for which is usually disappointing because of frequent relapses. In this article, we review the current evidence and discuss probable mechanisms of the association between rosacea and gastrointestinal comorbidities.

Small Intestinal Bacterial Overgrowth Syndrome: A Guide for the Appropriate Use of Breath Testing

The increased availability of noninvasive breath tests, each with limitations, has led to widespread testing for small intestinal bacterial overgrowth (SIBO) in patients with non-specific gastrointestinal complaints. The lactulose breath test (LBT) is based upon an incorrect premise and therefore incorrect interpretations which has resulted in the over-diagnosis of SIBO and the excessive use of antibiotics in clinical practice. Despite limitations, the glucose breath test (GBT) should be exclusively employed when considering SIBO in appropriately chosen patients. This review suggests guidelines for the optimal use and appropriate interpretation of the GBT for suspected SIBO. The LBT should be discarded from future use, and the literature based upon the LBT should be discounted accordingly.

Gut Microbial Dysbiosis in the Pathogenesis of Gastrointestinal Dysmotility and Metabolic Disorders

Of all microorganisms in the human body, the largest and most complex population resides in the gastrointestinal (GI) tract. The gut microbiota continuously adapts to the host environment and serves multiple critical functions for their hosts, including regulating host immunity, procuring energy from food, and preventing the colonization of pathogens. Mounting evidence has suggested gut microbial imbalance (dysbiosis) as a core pathophysiology in the development of GI motility and metabolic disorders, such as irritable bowel syndrome and diabetes. Current research has focused on discovering associations between these disorders and gut microbial dysbiosis; however, whether these associations are a consequence or cause is still mostly unexplored. State-of-the-art studies have investigated how gut microbes communicate with our body systems through microbiota-derived metabolites and how they are able to modulate host physiology. There is now mounting evidence that alterations in the composition of small intestinal microbes have an association with GI dysmotility and metabolic disorders. Although treatment options for gut microbial dysbiosis are currently limited, antibiotics, fecal microbiota transplantation, probiotics, and dietary interventions are currently the best options. However, treatment with broad-spectrum antibiotics has been viewed with skepticism due to the risk of developing antibiotic resistant bacteria. Studies are warranted to elucidate the cellular and molecular pathways underlying gut microbiota-host crosstalk and for the development of a powerful platform for future therapeutic approaches. Here, we review recent literature on gut microbial alterations and/or interactions involved in the pathophysiology of GI dysmotility and metabolic disorders.

Delayed Gastric Emptying Is Not Associated with a Microbiological Diagnosis of Small Intestinal Bacterial Overgrowth

BACKGROUND

Clinical symptoms of patients with small intestinal bacterial overgrowth (SIBO) may overlap with symptoms of gastroparesis. Prior studies suggest delayed small intestinal transit is associated with SIBO, but have not shown an association between delayed gastric emptying and SIBO. However, these studies have generally relied on the indirect method of breath testing to diagnose SIBO.

AIMS

The aim of this study was to examine the association between a microbiological diagnosis of SIBO and delayed gastric emptying by scintigraphy.

METHODS

In a single-center retrospective study of previous research participants who presented for small bowel enteroscopy for diagnostic evaluation of SIBO, we identified 73 participants who underwent gastric emptying study by scintigraphy. A microbiological diagnosis of SIBO was made in patients based on culture results of jejunal aspirates. Clinical symptoms were assessed using the total gastroparesis cardinal symptom index (GCSI) score. We compared delayed gastric emptying, 2- and 4-h gastric retention, and gastroparesis symptoms between patients with and without a microbiological diagnosis of SIBO.

KEY RESULTS

Among 29 participants with SIBO and 44 without SIBO, 33 (45%) had evidence of delayed gastric emptying. There was no significant association between a microbiological diagnosis of SIBO and delayed gastric emptying by scintigraphy. Percent retained at 2 and 4 h, and total GCSI scores did not differ significantly between those with and without SIBO.

CONCLUSIONS

Although delayed gastric emptying is common in patients with suspected SIBO, gastric emptying is not associated with a microbiological diagnosis of SIBO.

COLIGENTA treatment of small intestinal bacterial overgrowth. Results of an open study

PURPOSE

The treatment of small intestinal overgrowth (SIBO) varies according to the center. The present study aimed to evaluate the efficacy of COLIGENTA, an association of colimycin and gentamycin, on SIBO symptomatology and breath test normalization PATIENTS AND METHODS: In this prospective cross-sectional open study, 150 patients with functional bowel disorders and SIBO diagnosed by lactulose hydrogen breath test (LHBT) underwent COLIGENTA oral treatment. A new HLBT was performed 4 weeks after the first HLBT.

RESULTS

The patients were mainly female (74%), with a mean age of 47.4 ± 16.2 years and a body mass index of 26.2 ± 5.9 kg/m². After treatment, a decrease of expired hydrogen concentration (P<0.001) was found in the entire population. Improvement of gastrointestinal symptoms was found in 129 patients (86%), while the breath test's normalization was found in 62 patients (42%). Logistic regression showed that normalization of bowel symptoms was not associated with demographics, clinical, or hydrogen breath concentration. In contrast, normalization of LHBT was associated with an increase of breath hydrogen concentration at time 100 min during the first test (P = 0.003; OR=1.072; 95%CI= [1.023-1.123]).

CONCLUSION

The present study shows that 10-days of COLIGENTA treatment has a high SIBO clinical improvement rate and can be used as the first or second treatment line.

Irritable bowel syndrome

Irritable bowel syndrome is a functional gastrointestinal disorder with symptoms including abdominal pain associated with a change in stool form or frequency. The condition affects between 5% and 10% of otherwise healthy individuals at any one point in time and, in most people, runs a relapsing and remitting course. The best described risk factor is acute enteric infection, but irritable bowel syndrome is also more common in people with psychological comorbidity and in young adult women than in the rest of the general population. The pathophysiology of irritable bowel syndrome is incompletely understood, but it is well established that there is disordered communication between the gut and the brain, leading to motility disturbances, visceral hypersensitivity, and altered CNS processing. Other less reproducible mechanisms might include genetic associations, alterations in gastrointestinal microbiota, and disturbances in mucosal and immune function. In most people, diagnosis can be made on the basis of clinical history with limited and judicious use of investigations, unless alarm symptoms such as weight loss or rectal bleeding are present, or there is a family history of inflammatory bowel disease or coeliac disease. Once the diagnosis is made, an empathetic approach is key and can improve quality of life and symptoms, and reduce health-care expenditure. The mainstays of treatment include patient education about the condition, dietary changes, soluble fibre, and antispasmodic drugs. Other treatments tend to be reserved for people with severe symptoms and include central neuromodulators, intestinal secretagogues, drugs acting on opioid or 5-HT receptors, or minimally absorbed antibiotics (all of which are selected according to predominant bowel habit), as well as psychological therapies. Increased understanding of the pathophysiology of irritable bowel syndrome in the past 10 years has led to a healthy pipeline of novel drugs in development.

Predictors of Small Intestinal Bacterial Overgrowth in Symptomatic Patients Referred for Breath Testing

Background

Indications for a breath test (BT) are well established in the symptomatic patient with risk factors predisposing them to small intestinal bacterial overgrowth (SIBO). Characteristics and the profile of this population are not well known. Our objective was to study the characteristics of patients undergoing a BT for SIBO and to identify factors associated with a positive BT.

Methods

Retrospective study was conducted from 2012 to 2016 at the neurogastroenterology unit of the Centre Hospitalier de l'Universite de Montreal (CHUM). All patients who completed a BT (lactulose and/or glucose) were included. Demographics and clinical factors were analyzed to identify predictors of positive BT. Type of antibiotic treatment and clinical response were compiled. Groups of patients with (SIBO⁺) and without SIBO (SIBO^-) were also compared.

Results

A total of 136 patients were included in the study (mean age 51.2, range 20 - 80 years; 63% women), and SIBO was detected in 33.8% (n = 46). Both groups were similar in terms of age, body mass index, and gender. SIBO was significantly associated with the presence of abdominal pain (odds ratio (OR) = 4.78; P < 0.05), bloating (OR = 5.39; P < 0.05), smoking (OR = 6.66; P < 0.05), and anemia (OR = 4.08; P < 0.05). No association was identified with gender, age, obesity, and risk factors for SIBO. Antibiotics were used in 43% of patients with a positive BT, but clinical response was not significantly different in the subgroup that received antibiotics versus the subgroup that did not.

Conclusions

The prevalence of SIBO is high in symptomatic patients who underwent breath testing. Abdominal pain, bloating, smoking, and anemia are strongly associated with SIBO. Treatment of SIBO with antibiotics needs to be further investigated to better determine its efficacy on gastrointestinal symptoms.

Nutrient Challenge Testing Is Not Equivalent to Scintigraphy-Lactulose Hydrogen Breath Testing in Diagnosing Small Intestinal Bacterial Overgrowth

Background/Aims

Small intestinal bacterial overgrowth (SIBO) is a common condition in disorders of gut-brain interaction (DGBI). Recently, a combined scintigraphy–lactulose hydrogen breath test (ScLHBT) was described as an accurate tool diagnosing SIBO. We aim to analyze whether a lactulose nutrient challenge test (NCT), previously shown to separate DGBI from healthy volunteers, is equivalent to ScLHBT in diagnosing SIBO.

Methods

We studied data of 81 DGBI patients undergoing ScLHBT with 30 g lactulose and 300 mL water as well as NCT with 30 g lactulose and a 400 mL liquid test meal. Differences in proportion of positive SIBO diagnoses according to specified cecal load and time criteria for NCT and ScLHBT, respectively, were tested in an equivalence trial. An odds ratio (OR) range of 0.80-1.25 was considered equivalent.

Results

Diagnosis of SIBO during NCT was not equivalent to SIBO diagnosis in ScLHBT, considering a hydrogen increase before cecal load of 5.0%, 7.5%, or 10.0%, respectively ([OR, 3.76; 90% CI, 1.99-7.09], [OR, 1.87; 90% CI, 1.06-3.27], and [OR, 1.11; 90% CI, 0.65-1.89]). Considering only time to hydrogen increase as criterion, the odds of a positive SIBO diagnosis in the NCT (0.65) was lower than in ScLHBT (1.70) (OR, 0.38; 90% CI, 0.23-0.65).

Conclusions

This study could not show an equivalence of NCT and ScLHBT in diagnosing SIBO. A possible explanation might be the different transit times owing to unequal testing substances. The effect of this deviation in relation to consecutive therapy regimens should be tested in further prospective studies.