Factors That Affect Prevalence of Small Intestinal Bacterial Overgrowth in Chronic Pancreatitis: A Systematic Review, Meta-Analysis, and Meta-Regression

Fecal Coprococcus, hidden behind abdominal symptoms in patients with small intestinal bacterial overgrowth

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) is the presence of an abnormally excessive amount of bacterial colonization in the small bowel. Hydrogen and methane breath test has been widely applied as a non-invasive method for SIBO. However, the positive breath test representative of bacterial overgrowth could also be detected in asymptomatic individuals.

METHODS

To explore the relationship between clinical symptoms and gut dysbiosis, and find potential fecal biomarkers for SIBO, we compared the microbial profiles between SIBO subjects with positive breath test but without abdominal symptoms (PBT) and healthy controls (HC) using 16S rRNA amplicon sequencing.

RESULTS

Fecal samples were collected from 63 SIBO who complained of diarrhea, distension, constipation, or abdominal pain, 36 PBT, and 55 HC. For alpha diversity, the Shannon index of community diversity on the genus level showed a tendency for a slight increase in SIBO, while the Shannon index on the predicted function was significantly decreased in SIBO. On the genus level, significantly decreased Bacteroides, increased Coprococcus_2, and unique Butyrivibrio were observed in SIBO. There was a significant positive correlation between saccharolytic Coprococcus_2 and the severity of abdominal symptoms. Differently, the unique Veillonella in the PBT group was related to amino acid fermentation. Interestingly, the co-occurrence network density of PBT was larger than SIBO, which indicates a complicated interaction of genera. Coprococcus_2 showed one of the largest betweenness centrality in both SIBO and PBT microbiota networks. Pathway analysis based on the Kyoto Encyclopedia of Genes and Genome (KEGG) database reflected that one carbon pool by folate and multiple amino acid metabolism were significantly down in SIBO.

CONCLUSIONS

This study provides valuable insights into the fecal microbiota composition and predicted metabolic functional changes in patients with SIBO. Butyrivibrio and Coprococcus_2, both renowned for their role in carbohydrate fermenters and gas production, contributed significantly to the symptoms of the patients. Coprococcus's abundance hints at its use as a SIBO marker. Asymptomatic PBT individuals show a different microbiome, rich in Veillonella. PBT's complex microbial interactions might stabilize the intestinal ecosystem, but further study is needed due to the core microbiota similarities with SIBO. Predicted folate and amino acid metabolism reductions in SIBO merit additional validation.

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.

Exocrine pancreatic insufficiency and pancreatic exocrine replacement therapy in clinical practice

Exocrine pancreatic insufficiency (EPI) is a complex condition that disrupts normal digestion and absorption. Patients with EPI may suffer from mild to debilitating malabsorption with a constellation of symptoms that can have a significant effect on quality of life and nutrition status. Pancreatic enzyme replacement therapy (PERT) is effective and safe to treat EPI and is the standard of care for this condition. A wide variety and various forms of these products exist, as well as numerous guidelines and recommendations. Obtaining PERT for patients can oftentimes be cost prohibitive. Determining the presence and extent of EPI can be challenging and patient specific, making it difficult for practitioners. This narrative review will explore these issues, as well as several disease states potentially affected by EPI, and review current management strategies.

Helicobacter pylori infection and small intestinal bacterial overgrowth: a systematic review and meta-analysis

BACKGROUND

There is a link between Helicobacter pylori (HP) infection and small intestinal bacterial overgrowth (SIBO) with nonspecific digestive symptoms. Nonetheless, whether HP infection is associated with SIBO in adults remains unclear. Based on a meta-analysis, we evaluated this relationship.

RESULTS

Observational studies relevant to our research were identified by searching PubMed, Embase, the Cochrane Library, and the Web of Science. We evaluated between-study heterogeneity using the Cochrane Q test and estimated the I2 statistic. Random-effects models were used when significant heterogeneity was observed; otherwise, fixed-effects models were used. Ten datasets from eight studies, including 874 patients, were involved in the meta-analysis. It was shown that HP infection was related to a higher odds of SIBO (odds ratio [OR]: 1.82, 95% confidence interval: 1.29 to 2.58, p < 0.001) with mild heterogeneity (p for Cochrane Q test = 0.11, I2 = 7%). Subgroup analyses showed that HP infection was related to SIBO in young patients (mean age < 48 years, OR: 2.68, 95% CI: 1.67 to 4.28, p < 0.001; I2 = 15%) but not in older patients (mean age ≥ 48 years, OR: 1.15, 95% CI: 0.69 to 1.92, p < 0.60; I2 = 1%; p for subgroup difference = 0.02). Subgroup analyses further indicated that the association was not significantly affected by the country of study, comorbidities, exposure to proton pump inhibitors, or methods of evaluating HP infection and SIBO.

CONCLUSIONS

HP infection may be related to SIBO in adults, which supports the detection of SIBO in patients with digestive symptoms and HP infection.

Managing complications of chronic pancreatitis: a guide for the gastroenterologist

INTRODUCTION

Chronic pancreatitis is a heterogeneous and complex syndrome that, in most cases, causes pain as a cardinal symptom and affects both the morphology and function of the pancreas, leading to several serious complications.

AREAS COVERED

The present review, based on a non-systematic PubMed search updated to June 2023, aims to present the current available evidence on the role of gastroenterologists in the diagnosis and treatment of both local and systemic complications by either endoscopic or medical treatments.

EXPERT OPINION

At diagnosis and during chronic pancreatitis follow-up, particular care is needed to consider not only the clinically manifest signs and symptoms of the disease, such as pain, jaundice, gastrointestinal obstruction, and pseudocysts, which require multidisciplinary discussion to establish the best treatment option (endoscopic or surgical), but also less evident systemic complications. Pancreatic exocrine and endocrine insufficiency, together with chronic inflammation, addiction, and dysbiosis, contribute to malnutrition, sarcopenia, and osteopathy. These complications, in turn, increase the risk of infection, thromboembolic events, and death. Patients with chronic pancreatitis also have an increased risk of psychiatric disorders and pancreatic cancer onset. Overall, patients with chronic pancreatitis should receive a holistic evaluation, considering all these aspects, possibly through multidisciplinary care in dedicated expert centers.

Small intestinal bacterial overgrowth: current update

PURPOSE OF REVIEW

This article aims to provide an up-to-date review of small intestinal bacterial overgrowth (SIBO), including etiology and risk factors, clinical manifestations, diagnostic evaluation for suspected SIBO, and therapeutic options.

RECENT FINDINGS

Recent advances in breath testing, capsule and urine-based testing have opened new avenues and improved diagnostic yield of SIBO. Nonantibiotic-based treatment strategies have shown promising results in initial trials.

SUMMARY

Small intestinal bacterial overgrowth (SIBO) is a condition defined by the excess bacteria or changes in bacterial composition of the small intestine. These are associated with various gastrointestinal (GI) symptoms such as bloating, abdominal distension, diarrhea, nutrient deficiencies, and even frank weight loss. Small bowel jejunal aspirate of >10 5 CFU/ml has traditionally been considered the gold standard for diagnosis. Glucose and lactulose breath testing have become more common in clinical practice as they are noninvasive, easily accessible, and have lower cost. Treatment focuses on the eradication of excess bacteria in the small bowel and is traditionally done with the use of oral antibiotics. Other emerging therapies may include probiotics, diet manipulation, and prokinetic agents.

Gut microbiota controls the development of chronic pancreatitis: A critical role of short-chain fatty acids-producing Gram-positive bacteria

Chronic pancreatitis (CP) is a progressive and irreversible fibroinflammatory disorder, accompanied by pancreatic exocrine insufficiency and dysregulated gut microbiota. Recently, accumulating evidence has supported a correlation between gut dysbiosis and CP development. However, whether gut microbiota dysbiosis contributes to CP pathogenesis remains unclear. Herein, an experimental CP was induced by repeated high-dose caerulein injections. The broad-spectrum antibiotics (ABX) and ABX targeting Gram-positive (G+) or Gram-negative bacteria (G-) were applied to explore the specific roles of these bacteria. Gut dysbiosis was observed in both mice and in CP patients, which was accompanied by a sharply reduced abundance for short-chain fatty acids (SCFAs)-producers, especially G+ bacteria. Broad-spectrum ABX exacerbated the severity of CP, as evidenced by aggravated pancreatic fibrosis and gut dysbiosis, especially the depletion of SCFAs-producing G+ bacteria. Additionally, depletion of SCFAs-producing G+ bacteria rather than G- bacteria intensified CP progression independent of TLR4, which was attenuated by supplementation with exogenous SCFAs. Finally, SCFAs modulated pancreatic fibrosis through inhibition of macrophage infiltration and M2 phenotype switching. The study supports a critical role for SCFAs-producing G+ bacteria in CP. Therefore, modulation of dietary-derived SCFAs or G+ SCFAs-producing bacteria may be considered a novel interventive approach for the management of CP.

Evaluation and management of exocrine pancreatic insufficiency: pearls and pitfalls

PURPOSE OF REVIEW

The diagnosis and management of exocrine pancreatic dysfunction (EPD) can be challenging. EPD classically results from conditions that cause loss of pancreatic acinar cell function and decreased digestive enzyme production. However, several conditions may contribute to signs or symptoms of EPD with otherwise normal pancreatic exocrine function. A thoughtful approach to considering these conditions, along with their specific therapies, can guide a tailored management approach.

RECENT FINDINGS

An EPD severity classification schema has been proposed, which emphasizes a shift towards a more restrictive prescription of pancreas enzyme replacement therapy (PERT) for patients with milder EPD. In contrast, PERT use has been associated with a measurable survival benefit among individuals with EPD and pancreatic cancer, so the prescription of PERT may be more liberal in this population. Recent publications in the cystic fibrosis population offer pearls guiding the titration and optimization of PERT.

SUMMARY

Among individuals with severe EPD, PERT is an effective therapy. Among individuals with milder EPD, although PERT is effective, there may be opportunities to provide additional and potentially more effective therapies.

Epidemiology of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) is defined as an increase in the bacterial content of the small intestine above normal values. The presence of SIBO is detected in 33.8% of patients with gastroenterological complaints who underwent a breath test, and is significantly associated with smoking, bloating, abdominal pain, and anemia. Proton pump inhibitor therapy is a significant risk factor for SIBO. The risk of SIBO increases with age and does not depend on gender or race. SIBO complicates the course of a number of diseases and may be of pathogenetic significance in the development of their symptoms. SIBO is significantly associated with functional dyspepsia, irritable bowel syndrome, functional abdominal bloating, functional constipation, functional diarrhea, short bowel syndrome, chronic intestinal pseudo-obstruction, lactase deficiency, diverticular and celiac diseases, ulcerative colitis, Crohn’s disease, cirrhosis, metabolic-associated fatty liver disease (MAFLD), primary biliary cholangitis, gastroparesis, pancreatitis, cystic fibrosis, gallstone disease, diabetes, hypothyroidism, hyperlipidemia, acromegaly, multiple sclerosis, autism, Parkinson’s disease, systemic sclerosis, spondylarthropathy, fibromyalgia, asthma, heart failure, and other diseases. The development of SIBO is often associated with a slowdown in orocecal transit time that decreases the normal clearance of bacteria from the small intestine. The slowdown of this transit may be due to motor dysfunction of the intestine in diseases of the gut, autonomic diabetic polyneuropathy, and portal hypertension, or a decrease in the motor-stimulating influence of thyroid hormones. In a number of diseases, including cirrhosis, MAFLD, diabetes, and pancreatitis, an association was found between disease severity and the presence of SIBO. Further work on the effect of SIBO eradication on the condition and prognosis of patients with various diseases is required.

Understanding Our Tests: Hydrogen-Methane Breath Testing to Diagnose Small Intestinal Bacterial Overgrowth

There is increasing appreciation that small intestinal bacterial overgrowth (SIBO) drives many common gastrointestinal symptoms, including diarrhea, bloating, and abdominal pain. Breath testing via measurement of exhaled hydrogen and methane gases following ingestion of a readily metabolized carbohydrate has become an important noninvasive testing paradigm to help diagnose SIBO. However, because of a number of physiological and technical considerations, how and when to use breath testing in the diagnosis of SIBO remains a nuanced clinical decision. This narrative review provides a comprehensive overview of breath testing paradigms including the indications for testing, how to administer the test, and how patient factors influence breath testing results. We also explore the performance characteristics of breath testing (sensitivity, specificity, positive and negative predictive values, likelihood ratios, and diagnostic odds ratio). Additionally, we describe complementary and alternative tests for diagnosing SIBO. We discuss applications of breath testing for research. Current estimates of SIBO prevalence among commonly encountered high-risk populations are reviewed to provide pretest probability estimates under a variety of clinical situations. Finally, we discuss how to integrate breath test performance characteristics into clinical care decisions using clinical predictors and the Fagan nomogram.

Utility of Fecal Elastase-1 to diagnose severe exocrine insufficiency in chronic pancreatitis: Real world experience

INTRODUCTION

Quantitative fecal fat estimation is the gold standard test to diagnose steatorrhea (fecal fat >7 g/day) in chronic pancreatitis (CP), but cumbersome and inconvenient. So, fecal elastase-1 (FE) is proposed as a good alternative but the data on the diagnostic utility of FE to diagnose steatorrhea is variable.

METHODS

This retrospective study included adult CP patients evaluated with both 24-h fecal-fat and FE tests within a 3-month period. The objective was to evaluate the diagnostic performance of FE to diagnose steatorrhea and to evaluate the FE progression over 9-month period.

RESULTS

Among the 147 included patients, the frequency of steatorrhea (fecal fat >7 g/day) was 34%. The sensitivity, specificity, and negative likelihood ratio (LR) of FE was 90%, 28.9% and 0.35 at cut-off of <100 μg/g stool to diagnose steatorrhea; and 96%, 11.3% and 0.35 at cut-off of <200 μg/g stool, respectively. The optimal cut-off of FE was <20 on receiver operating characteristic curve (sensitivity 66%; specificity 69%; positive LR 2.14). There was no statistically significant variation in FE levels over 9 months interval among a hundred patients.

CONCLUSION

Compared to FE ≥ 200 μg/g stool, FE ≥ 100 can used to exclude steatorrhea (better specificity and negative LR). FE < 20 alone cannot replace fecal fat estimation to confirm steatorrhea but to be interpreted with clinical features. Repeat FE testing for exocrine insufficiency progression can be done at least a year later.

What is the significance of a faecal elastase-1 level between 200 and 500μg/g?

Background

Pancreatic exocrine insufficiency is a cause of malabsorption. It is generally diagnosed if faecal elastase-1 (FE-1) levels are below 200 µg/g. Pancreatic function is assumed to be normal when faecal elastase levels are >500 µg/g. The significance of faecal elastase levels above 200 µg/g but less than 500 µg/g is unclear.

Methods

This retrospective study reports the response to treatment in patients who had an FE-1 level between 200 and 500 µg/g.

Results

Of these 82 patients, 28 were offered pancreatic enzyme replacement therapy (PERT). A clinical response, defined as an improvement in their initial symptoms after commencing PERT, was seen in 20 patients (71%), 7 with potentially predisposing conditions and 13 with functional diarrhoea. PERT particularly abolished or improved diarrhoea, steatorrhoea and flatulence.

Conclusion

Clinicians should, therefore, be aware that a trial of PERT given to patients with FE-1 levels between 200 and 500 µg/g may lead to improvement in gastrointestinal symptoms.

Berberine and rifaximin effects on small intestinal bacterial overgrowth: Study protocol for an investigator-initiated, double-arm, open-label, randomized clinical trial (BRIEF-SIBO study)

Introduction: Small intestinal bacterial overgrowth (SIBO) leads to non-specific abdominal discomfort and nutrient malabsorption. Currently, rifaximin is widely applied in SIBO based on its antibacterial and non-absorbable nature. Berberine is a natural component of many popular medicine plants that ameliorates intestinal inflammation in humans through its modification of the gut microbiota. Potential effect of berberine to the gut may provide therapeutic target for SIBO. We aimed to evaluate the effect of berberine compared with rifaximin on SIBO patients. Methods: This is an investigator-initiated, single-center, open-label, double-arm randomized controlled trial, termed BRIEF-SIBO (Berberine and rifaximin effects for small intestinal bacterial overgrowth). In total, 180 patients will be recruited and allocated to an intervention group (berberine) and a control group (rifaximin). Each participant will receive one 400 mg drug twice a day (800 mg daily) for 2 weeks. The total follow-up period is 6 weeks from the start of medication. The primary outcome is a negative breath test. The secondary outcomes include abdominal symptom relief and alteration in gut microbiota. Efficacy assessment will be performed every 2 weeks, as well as safety assessment during the treatment. The primary hypothesis is that berberine is not inferior to rifaximin for SIBO. Discussion: The BRIEF-SIBO study is the first clinical trial assessing the eradication effects of 2 weeks of berberine treatment in SIBO patients. The effect of berberine will be fully verified by using rifaximin as the positive control. The findings of this study may have implications for the management of SIBO, especially increasing the awareness of both physicians and patients who are suffering from long-term abdominal discomfort and avoiding excessive examination.

Microbiota in the Natural History of Pancreatic Cancer: From Predisposition to Therapy

Early microbiome insights came from gut microbes and their role among intestinal and extraintestinal disease. The latest evidence suggests that the microbiota is a true organ, capable of several interactions throughout the digestive system, attracting specific interest in the biliopancreatic district. Despite advances in diagnostics over the last few decades and improvements in the management of this disease, pancreatic cancer is still a common cause of cancer death. Microbiota can influence the development of precancerous disease predisposing to pancreatic cancer (PC). At the same time, neoplastic tissue shows specific characteristics in terms of diversity and phenotype, determining the short- and long-term prognosis. Considering the above information, a role for microbiota has also been hypothesized in the different phases of the PC approach, providing future revolutionary therapeutic insights. Microbiota-modulating therapies could open new issues in the therapeutic landscape. The aim of this narrative review is to assess the most updated evidence on microbiome in all the steps regarding pancreatic adenocarcinoma, from early development to response to antineoplastic therapy and long-term prognosis.

Responses of Ileal and Fecal Microbiota to Withdrawal of Pancreatic Enzyme Replacement Therapy in a Porcine Model of Exocrine Pancreatic Insufficiency

Little is known regarding the interplay between microbiota and pancreas functions in humans as investigations are usually limited to distal sites, namely the analyses of fecal samples. The aim of this study was to investigate both ileal and fecal microbiota in response to pancreatic enzyme replacement therapy (PERT) in a porcine model of exocrine pancreatic insufficiency (EPI). PERT was stopped for ten days in ileo-cecal fistulated minipigs with experimentally induced EPI (n = 8) and ileal digesta as well as fecal samples were obtained before withdrawal, during withdrawal and after the reintroduction of PERT. Profound community changes occurred three days after enzyme omission and were maintained throughout the withdrawal phase. A reduction in α-diversity together with relative abundance changes in several taxa, in particular increases in Bifidobacteria (at both sites) and Lactobacilli (only feces) were observed. Overall, dysbiosis events from the ileum had accumulating effects in distal parts of the gastrointestinal tract with additional alterations occurring only in the colon. Changes were reversible after continuing PERT, and one week later, bacterial communities resembled those at baseline. Our study demonstrates the rapid and profound impacts of enzyme withdrawal in bacterial communities, contributing to our understanding of the interplay between pancreas function and microbiota.

Changes in the Intestinal Microbiota in Patients with Chronic Pancreatitis: Systematizing Literature Data

The purpose of the review. To systematize literature data on changes in the structure of the intestinal microbiota in patients with chronic pancreatitis (CP).Key findings. The human intestinal microbiota is a dynamically changing system that is constantly undergoing qualitative and quantitative changes, especially in several pathological conditions of the digestive system. At present, the differences in the intestinal microbiota in pancreatic diseases are poorly understood. The severe CP is associated with impaired synthesis of antimicrobial peptides, bicarbonates, and digestive enzymes by the pancreas, which is a risk factor for dysbiotic changes in the intestinal microbiota, consisting in the development of small intestinal bacterial overgrowth (SIBO) and gut dysbiosis. The results of two large meta-analyses show that about a third of CP patients have SIBO. The colonic microbiota in patients with CP is also characterized by dysbiotic disorders, primarily in the reduction of alpha-diversity. Some studies have shown that these patients have an increase in Firmicutes, while Bacteroides and Faecalibacterium are reduced. In addition, as a rule, in patients with CP, the growth of Escherichia, Shigella and Streptococcus is recorded.Conclusion. In general, scientific papers have revealed significant heterogeneity in the profiles of the intestinal microbiota in patients with CP. Thus, several questions remain open, prioritizing the further study of the intestinal microbiota in patients with CP for identifying the specifics of its structure that can personalize the selection of enzyme replacement therapy and restrict the unreasonable prescription of additional pharmacotherapy (the use of proton pump inhibitors and / or antibacterial drugs).

Factors Affecting the Circulating Levels of Oxyntomodulin in Health and After Acute Pancreatitis

OBJECTIVES

To investigate the factors associated with the circulating levels of oxyntomodulin in healthy individuals and individuals after an episode of acute pancreatitis (AP).

METHODS

Blood samples were collected from all participants after an overnight fast and analyzed for 28 biomarkers. Participants also underwent comprehensive body composition analysis on a 3-T magnetic resonance imaging scanner. Regression analyses were done to investigate the associations between oxyntomodulin and the studied factors.

RESULTS

The study included 105 individuals who had a primary diagnosis of AP and 58 healthy individuals. Peptide YY (B coefficient, 0.094; 95% confidence interval [95% CI], 0.164-0.123), pancreatic polypeptide (0.048; 95% CI, 0.030-0.066), and leptin (0.394; 95% CI, 0.128-0.661) had significant associations with oxyntomodulin in healthy individuals. Peptide YY was the most prominent factor associated with oxyntomodulin, explaining 60% of its variance in health. Cholecystokinin (0.014; 95% CI, 0.010-0.018), amylin (-0.107; 95% CI, -0.192 to -0.021), and glycated hemoglobin (-0.761; 95% CI, -1.249 to -0.273) had significant associations with oxyntomodulin in individuals after AP. Cholecystokinin was the most prominent factor associated with oxyntomodulin, explaining 44% of its variance after AP.

CONCLUSIONS

Factors affecting the circulating levels of oxyntomodulin are different in health and after AP. These insights will enable the determination of populations that benefit from oxyntomodulin therapeutics in the future.

Practical Recommendation of the Scientific Сommunity for Human Microbiome Research (CHMR) and the Russian Gastroenterological Association (RGA) on Small Intestinal Bacterial Overgrowth in Adults

Aim. To optimize the choice of treatment strategies by physicians and gastroenterologists to improve treatment and prevention of small intestinal bacterial overgrowth (SIBO) in adults.

Key points. SIBO is a condition characterized by an increased amount and/or abnormal composition of the microbiota in the small intestine. Clinically, the syndrome is manifested by nonspecific gastroenterological complaints and the development of malabsorption syndrome. Most often, SIBO is associated with various chronic non- infectious diseases (both diseases of the gastrointestinal tract, and the cardiovascular system and the neuromuscular apparatus) and can affect the severity of their symptoms. Specific methods for diagnosing SIBO are the culture method and breath tests. The main approaches to the treatment of SIBO include the elimination of the underlying cause of its occurrence, the use of antibacterial drugs and adherence to dietary recommendations (elemental diet).

Conclusion. Small intestinal bacterial overgrowth is common in patients with various diseases, but has non-specific manifestations, so proper diagnosis of this condition is required. SIBO therapy involves prescription of antibacterial agents, the most studied of which is the non-absorbable antibiotic rifaximin-α.

Complex Role of Microbiome in Pancreatic Tumorigenesis: Potential Therapeutic Implications

Pancreatic cancer (PC) is the fourth leading cause of cancer-related mortality with limited diagnostic and therapeutic options. Although immunotherapy has shown promise in the treatment of several cancers, its role in pancreatic cancer is rather limited. Several studies have focused on determining the role of the tumor microenvironment with cancer-cell-intrinsic events and tumor-infiltrating immune cellular properties. However, in the past decade, there has been emerging research aimed at delineating the role of the host microbiome, including the metabolites from microbes and host responses, on pancreatic tumorigenesis. Importantly, there is emerging evidence suggesting the beneficial role of a gut microbiome transplant to improve immunotherapeutic outcomes in cancer patients. In this review, we summarize the recent understanding of the role of the microbiome in pancreatic cancer progression, along with its clinical diagnostic and therapeutic implications.

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.

[Chronic pancreatitis: update diagnostic and therapeutic concepts]

INTRODUCTION

Chronic pancreatitis (CP) is a frequent cause for hospitalization and is associated with impaired quality of life and reduced overall survival. The German Society for Gastroenterology (DGVS) has recently completed the S3-Guideline "Pancreatitis" that summarizes key findings on epidemiology, diagnostic and therapeutic concepts for acute and chronic pancreatitis. Here, we recapitulate the most relevant findings for clinicians regarding CP.

RESULTS

The most common cause of CP is chronic alcohol abuse, other causes are hereditary pancreatitis, autoimmune pancreatitis, hyperparathyroidism and idiopathic forms. Apart from the classical hereditary pancreatitis (PRSS1 mutation), a number of genetic associations have been discovered over the last years that are associated with an increased risk to develop idiopathic CP. The conservative management of CP is focused on the appropriate management of exocrine and endocrine insufficiency, and the prevention and treatment of secondary complications such as osteoporosis, vitamin deficiencies and malnutrition. Local complications (bile duct stenosis, duodenal stenosis, pseudocysts and chronic pain) should be managed in multidisciplinary teams in specialized pancreas centres with expert surgeons, radiologists and gastroenterologists. Infected or symptomatic pseudocysts should be primarily addressed by endoscopic drainage. In contrast, patients with chronic pain, dilated pancreas duct and opioid use should be considered for early surgical intervention.

CONCLUSION

Chronic pancreatitis is associated with increased morbidity and mortality and often leads to hospital admissions. The clinical management of complex patients with local complications requires an interdisciplinary approach to tailor available therapeutic modalities depending on the stage of the disease and pre-existing comorbidities.

The Gut Microbiome in Patients With Chronic Pancreatitis Is Characterized by Significant Dysbiosis and Overgrowth by Opportunistic Pathogens

Exocrine pancreatic function is a critical host factor in determining the intestinal microbiota composition. Diseases affecting the exocrine pancreas could therefore influence the gut microbiome. We investigated the changes in gut microbiota of patients with chronic pancreatitis (CP).

Gut microbiota in pancreatic diseases: possible new therapeutic strategies

Pancreatic diseases such as pancreatitis, type 1 diabetes and pancreatic cancer impose substantial health-care costs and contribute to marked morbidity and mortality. Recent studies have suggested a link between gut microbiota dysbiosis and pancreatic diseases; however, the potential roles and mechanisms of action of gut microbiota in pancreatic diseases remain to be fully elucidated. In this review, we summarize the evidence that supports relationship between alterations of gut microbiota and development of pancreatic diseases, and discuss the potential molecular mechanisms of gut microbiota dysbiosis in the pathogenesis of pancreatic diseases. We also propose current strategies toward gut microbiota to advance a developing research field that has clinical potential to reduce the cost of pancreatic diseases.

The gut microbiome in pancreatogenic diabetes differs from that of Type 1 and Type 2 diabetes

We hypothesized that the gut microbiome in patients with diabetes secondary to chronic pancreatitis (Type 3c) is different from those with Type 1 and Type 2 diabetes. This was a cross-sectional preliminary study that included 8 patients with Type 1, 10 with Type 2, 17 with Type 3c diabetes and 9 healthy controls. Demographic, clinical, biochemical, imaging and treatment data were recorded and sequencing of the V3-V4 region of the bacterial 16SrRNA was done on fecal samples. Bioinformatics and statistical analyses was performed to evaluate the differences in the diversity indices, distance matrices, relative abundances and uniqueness of organisms between the types of diabetes. There was significant difference in the species richness. Beta diversity was significantly different between patients with Type 3c diabetes and the other groups. 31 genera were common to all the three types of diabetes. There was significant differences in the species level taxa between Type 3c diabetes and the other groups. The unique bacterial species signature in Type 3c diabetes compared to Type 1 and Type 2 diabetes included Nesterenkonia sp. AN1, Clostridium magnum, Acinetobacter lwoffii, Clostridium septicum, Porphyromonas somerae, Terrabacter tumescens, and Synechococus sp.

Exocrine Pancreatic Function Modulates Plasma Metabolites Through Changes in Gut Microbiota Composition

PURPOSE

Exocrine pancreatic function is critically involved in regulating the gut microbiota composition. At the same time, its impairment acutely affects human metabolism. How these 2 roles are connected is unknown. We studied how the exocrine pancreas contributes to metabolism via modulation of gut microbiota.

DESIGN

Fecal samples were collected in 2226 participants of the population-based Study of Health in Pomerania (SHIP/SHIP-TREND) to determine exocrine pancreatic function (pancreatic elastase enzyme-linked immunosorbent assay) and intestinal microbiota profiles (16S ribosomal ribonucleic acid gene sequencing). Plasma metabolite levels were determined by mass spectrometry.

RESULTS

Exocrine pancreatic function was associated with changes in the abundance of 28 taxa and, simultaneously, with those of 16 plasma metabolites. Mediation pathway analysis revealed that a significant component of how exocrine pancreatic function affects the blood metabolome is mediated via gut microbiota abundance changes, most prominently, circulating serotonin and lysophosphatidylcholines.

CONCLUSION

These results imply that the effect of exocrine pancreatic function on intestinal microbiota composition alters the availability of microbial-derived metabolites in the blood and thus directly contributes to the host metabolic changes associated with exocrine pancreatic dysfunction.

Nutritional management of chronic pancreatitis: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Malnutrition is a frequent complication of chronic pancreatitis. Adequate nutritional support is imperative, but there is still uncertainty about the optimal nutritional treatment. This work systematically compiles evidence from randomized controlled trials investigating dietary interventions in chronic pancreatitis and, in a further step, contrasts those findings with existing dietary recommendations.

METHODS

The literature search (PubMed and Cochrane Central Register of Controlled Trials) included English and German full-text articles, which had been published in peer-reviewed journals. Two independent reviewers identified and selected studies. For meta-analysis, forest plots with 95% confidence intervals were generated using a random-effects model.

RESULTS

Eleven randomized controlled trials fulfilled all selection criteria. In these trials, the following dietary interventions were tested: antioxidant treatment (n = 6), vitamin D supplementation (n = 3), supplementation with oral nutritional supplements (n = 1), and symbiotics supplementation (n = 1). Studies were of good methodological quality (mean Jadad score of 3.6) but heterogeneous in terms of interventions and study populations. Only for vitamin D, there was convincing evidence for efficacy of supplementation. We found no effect for antioxidant treatment on pain relief (standardized mean difference = -0.12; 95% confidence interval -0.73 to 0.48) and limited generalizability for interventions with oral nutritional supplements and symbiotics.

CONCLUSIONS

Nutritional management in chronic pancreatitis remains challenging. As well-designed randomized controlled trials are scarce, in large part, recommendations can only be based on low-level evidence studies or expert opinion. For now, consumption of a balanced diet remains the cornerstone recommendation for prevention, whereas more goal-directed interventions are indicated for specific nutrient deficiencies.

Molecular Mechanism Contributing to Malnutrition and Sarcopenia in Patients with Liver Cirrhosis

Liver cirrhosis is frequently accompanied by disease-related malnutrition (DRM) and sarcopenia, defined as loss of skeletal muscle mass and function. DRM and sarcopenia often coexist in cirrhotic patients and are associated with increased morbidity and mortality. The clinical manifestation of both comorbidities are triggered by multifactorial mechanisms including reduced nutrient and energy intake caused by dietary restrictions, anorexia, neuroendocrine deregulation, olfactory and gustatory deficits. Maldigestion and malabsorption due to small intestinal bacterial overgrowth, pancreatic insufficiency or cholestasis may also contribute to DRM and sarcopenia. Decreased protein synthesis and increased protein degradation is the cornerstone mechanism to muscle loss, among others mediated by disease- and inflammation-mediated metabolic changes, hyperammonemia, increased myostatin and reduced human growth hormone. The concise pathophysiological mechanisms and interactions of DRM and sarcopenia in liver cirrhosis are not completely understood. Furthermore, most knowledge in this field are based on experimental models, but only few data in humans exist. This review summarizes known and proposed molecular mechanisms contributing to malnutrition and sarcopenia in liver cirrhosis and highlights remaining knowledge gaps. Since, in the prevention and treatment of DRM and sarcopenia in cirrhotic patients, more research is needed to identify potential biomarkers for diagnosis and development of targeted therapeutic strategies.

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.

Gut Microbiome, Intestinal Permeability, and Tissue Bacteria in Metabolic Disease: Perpetrators or Bystanders?

The emerging evidence on the interconnectedness between the gut microbiome and host metabolism has led to a paradigm shift in the study of metabolic diseases such as obesity and type 2 diabetes with implications on both underlying pathophysiology and potential treatment. Mounting preclinical and clinical evidence of gut microbiota shifts, increased intestinal permeability in metabolic disease, and the critical positioning of the intestinal barrier at the interface between environment and internal milieu have led to the rekindling of the "leaky gut" concept. Although increased circulation of surrogate markers and directly measurable intestinal permeability have been linked to increased systemic inflammation in metabolic disease, mechanistic models behind this phenomenon are underdeveloped. Given repeated observations of microorganisms in several tissues with congruent phylogenetic findings, we review current evidence on these unanticipated niches, focusing specifically on the interaction between gut permeability and intestinal as well as extra-intestinal bacteria and their joint contributions to systemic inflammation and metabolism. We further address limitations of current studies and suggest strategies drawing on standard techniques for permeability measurement, recent advancements in microbial culture independent techniques and computational methodologies to robustly develop these concepts, which may be of considerable value for the development of prevention and treatment strategies.

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.

Metabolic Trifecta After Pancreatitis: Exocrine Pancreatic Dysfunction, Altered Gut Microbiota, and New-Onset Diabetes

Pancreatitis, a complex disease influenced by both genetic and environmental factors, often leads to metabolic sequelae (such as exocrine pancreatic dysfunction and new-onset diabetes). Several trillion micro-organisms inhabit the gastrointestinal tract, and this community plays an important role in the regulation of functions of not only the gut but also the pancreas. Studies to parse the underlying contributions of the gut microbiota to metabolic sequelae of pancreatitis will offer important translational insights with a view to preventing exocrine pancreatic dysfunction and new-onset diabetes after pancreatitis.