How to Test and Treat Small Intestinal Bacterial Overgrowth: an Evidence-Based Approach

Intestinal Methanogen Overgrowth (IMO) Is Associated with Delayed Small Bowel and Colonic Transit Time (TT) on the Wireless Motility Capsule (WMC)

BACKGROUND

Methanogens are associated with gut dysmotility in animal models but have not been robustly studied in humans. The WMC assesses regional transit time (TT) and pH in the GI tract.

AIMS

To study the segmental TT and pH among patients with SIBO or IMO utilizing WMC.

METHODS

We conducted a retrospective study of 207 patients who underwent a glucose or lactulose breath test (BT) and WMC from 2010 to 2022. Diagnosis of SIBO and IMO were based on the 2017 North American consensus criteria. TT and pH were extracted from WMC recordings. We tested for differences in means of continuous variables and frequencies of categorical variables using two-sample t tests, Wilcoxon Rank Sum test, Chi-square, and Fisher exact tests. We used R version 3.3.1 (2016-06-21) for all statistical analyses.

RESULTS

A total of 196 patients met criteria, mean age 47.4 years and 155 (79.1%) females. Of the 86 (43.9%) patients with a positive BT, 42 (58.3%) had IMO only (meeting only CH4 criteria) and 30 (34.9%) met both H2 and CH4 criteria. Colonic TT was longer in patients with a positive BT compared to negative patients (40 h:29 min vs 28 h:51 min, p = 0.028). Small bowel TT and colonic TT were longer in patients with IMO compared to negative patients (SBTT: 5 h:15 min vs 4 h:32 min, p = 0.021; CTT: 44 h:23 min vs 28 h:51 min, p = 0.030). There were no significant differences in segmental pH compared to negative patients.

CONCLUSION

To our knowledge, this is the largest study of patients who have undergone both BT and WMC. A positive BT was associated with delayed CTT, while having IMO only was associated with both delayed CTT and SBTT, but neither with pH. Future investigation is needed to elucidate whether changes in intestinal microbiota affect gut transit.

Differences in clinical manifestations and the fecal microbiome between irritable bowel syndrome and small intestinal bacterial overgrowth

BACKGROUND

Irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) share similar abdominal symptoms; however, their differentiation remains controversial.

AIMS

To illustrate the differences between the two conditions.

METHODS

Patients and healthy controls completed questionnaires and provided stool samples for analysis.

RESULTS

IBS presented with the most severe symptoms and was specifically characterized by intense abdominal pain and frequent episodes of diarrhea. Patients with IBS displayed more dysregulated taxonomy within the fecal microbiota than SIBO. Opportunistic pathogens, including Lachnoclostridium, Escherichia-Shigella, and Enterobacter were enriched in the IBS group which contributed to increased bacterial pathogenicity and positively correlated with abdominal pain and bloating, meanwhile, Lachnoclostridium and Escherichia-Shigella were found to be associated with metabolites affiliated to bile acids, alcohols and derivatives. Bacteria enriched in SIBO group correlated with constipation. The bacterial co-occurrence network within the SIBO group was the most intricate. Ruminococcaceae Group were defined as core bacteria in SIBO. Differential metabolites affiliated to androstane steroids and phenylacetic acids were associated with core bacteria.

CONCLUSIONS

Our study elucidates the differences between IBS and SIBO in terms of symptoms, microbiota and functions, which provides insights into a better understanding of both diseases and evidence for different treatment strategies.

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.

Prospective Monitoring of Small Intestinal Bacterial Overgrowth After Gastric Bypass: Clinical, Biological, and Gas Chromatographic Aspects

BACKGROUND AND AIMS

Obesity is a predisposing factor for small intestinal bacterial overgrowth (SIBO). The aim of this study was to prospectively evaluate the prevalence of SIBO as well as its clinical, biological, and nutritional aspects before and up to 24 months after a Roux-en-Y gastric bypass (RYGB) surgery.

PATIENTS AND METHODS

Fifty-one patients (mean BMI 46.9 kg/m2, 66.7% women) requesting RYGB were included between 2016 and 2020. Each patient underwent a glucose breath test, a standardized interrogation on functional digestive signs, a dietary survey, a blood test, a fecalogram, and anthropometric data gathering. These investigations were carried out before surgery and at 1, 3, 6, 9, 12, 18, and 24 months after RYGB.

RESULTS

Before surgery, we found a prevalence of 17.6% of SIBO (95% CI = [8.9%; 31.4%]). After RYGB, at the end of 24 months of follow-up, 89.5% of patients developed SIBO. Anal incontinence appeared to be very frequent after surgery, affecting 18.8% of our population 18 months after surgery. We observed positive steatorrhea after surgery with an average of 11.1 g of lipids/24 h despite a significant limitation of dietary lipids (p = 0.0282).

CONCLUSION

Our study corroborates data in the literature on the prevalence of SIBO in severe obesity patients. For the first time, we observed the sudden appearance of SIBO after RYGB, with a correlation between exhaled hydrogen on a breath test and lipid malabsorption on the fecalogram. As a result, these patients develop fatty diarrhea, with frequent fecal incontinence.

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.

Dietary Intervention Improves Gastrointestinal Symptoms after Treatment of Cancer in the Pelvic Organs

Gastrointestinal (GI) symptoms are common in patients receiving radiotherapy, chemotherapy, and/or surgery for cancer in the pelvic organs. The aim of the present prospective cohort study was to report the efficacy of dietary intervention in patients with chronic GI sequelae to treatment of cancer in pelvic organs and insufficient symptomatic effect of medical treatment. Eighty-eight patients were offered specialist dietitian guidance. Gastrointestinal symptoms and quality of life were assessed before and after intervention by validated questionnaires. The main dietary interventions were low-fat diet (n = 44; 50%), modification of dietary fiber content (n = 19; 33%), dietary restrictions with a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet (n = 18; 20%), gluten-free diet (n = 1; 1%), and other dietary advice (n = 6; 7%). Compared to baseline, dietary intervention improved quality of life (EQ5D scale) (p < 0.01), bowel function for the last four weeks (p < 0.02), stool frequency (p < 0.03), constipation (p < 0.05), incomplete rectal emptying at defecation (p < 0.02), and performing usual activities (p < 0.0). In conclusion, this observational study using tailored dietary intervention showed that symptoms can be reduced and quality of life can be improved in patients with chronic GI sequelae following treatment of cancer in the pelvic organs not responding sufficiently to medical treatment.

The Role of Small Intestinal Bacterial Overgrowth in Obesity and Its Related Diseases

Obesity has become a major public health problem worldwide and its occurrence is increasing globally. Obesity has also been shown to be involved in the occurrence and development of many diseases and pathological conditions, such as nonalcoholic fatty liver disease (NAFLD), type 2 diabetes mellitus (T2DM), insulin resistance (IR). In recent years, gut microbiota has received extensive attention as an important regulatory part involved in host diseases and health status. A growing body of evidence suggests that gut microbiota dysbiosis has a significant adverse effect on the host. Small intestinal bacterial overgrowth (SIBO), a type of intestinal microbial dysbiosis, has been gradually revealed to be associated with obesity and its related diseases. The presence of SIBO may lead to the destruction of intestinal barrier integrity, increased intestinal permeability, increased endotoxin levels, activation of inflammatory responses, and translocation of bacteria from the colon to the small intestine. However, the causal relationship between SIBO and obesity and the specific mechanisms have not been well elucidated. This review discusses the cross-talk between SIBO and obesity and its related diseases, and expounds its potential mechanisms and interventions, which may help to discover new therapeutic targets for obesity and its related diseases and develop treatment options.

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.

Disease mechanisms as subtypes: Microbiome

Abnormalities in gut microbiota have been suggested to be involved in the pathophysiology and progression of Parkinson's disease (PD). Gastrointestinal nonmotor symptoms often precede the onset of motor features in PD, suggesting a role for gut dysbiosis in neuroinflammation and α-synuclein (α-syn) aggregation. In the first part of this chapter, we analyze critical features of healthy gut microbiota and factors (environmental and genetic) that modify its composition. In the second part, we focus on the mechanisms underlying the gut dysbiosis and how it alters anatomically and functionally the mucosal barrier, triggering neuroinflammation and subsequently α-syn aggregation. In the third part, we describe the most common alterations in the gut microbiota of PD patients, dividing the gastrointestinal system in higher and lower tract to examine the association between microbiota abnormalities and clinical features. In the final section, we report on current and future therapeutic approaches to gut dysbiosis aiming to either reduce the risk for PD, modify the disease course, or improve the pharmacokinetic profile of dopaminergic therapies. We also suggest that further studies will be needed to clarify the role of the microbiome in PD subtyping and of pharmacological and nonpharmacological interventions in modifying specific microbiota profiles in individualizing disease-modifying treatments in PD.

Methanogenic archaea in the human gastrointestinal tract

The human microbiome is strongly interwoven with human health and disease. Besides bacteria, viruses and eukaryotes, numerous archaea are located in the human gastrointestinal tract and are responsible for methane production, which can be measured in clinical methane breath analyses. Methane is an important readout for various diseases, including intestinal methanogen overgrowth. Notably, the archaea responsible for methane production are largely overlooked in human microbiome studies due to their non-bacterial biology and resulting detection issues. As such, their importance for health and disease remains largely unclear to date, in particular as not a single archaeal representative has been deemed to be pathogenic. In this Perspective, we discuss the current knowledge on the clinical relevance of methanogenic archaea. We explain the archaeal unique response to antibiotics and their negative and positive effects on human physiology, and present the current understanding of the use of methane as a diagnostic marker.

Gastrointestinal involvement in systemic sclerosis: An updated review

The gastrointestinal tract (GI) is the second most affected organ system in individuals suffering from systemic/localized scleroderma (SSc) or localized scleroderma. SSc can affect any part of the GI, between the oral cavity and anorectum. The annual incidence of SSc in the United States is estimated to be 19.3 cases per million adults, with the highest incidence reported in people aged 44 to 55. Females are 5 times more likely than males to suffer from SSc. Morbidity and mortality rates associated with SSc are predominantly elevated among patients with GI manifestations. Esophageal and intestinal manifestations impact 90% and 40% to 70% of patients with systemic scleroderma, respectively. SSc patients are known to suffer from small bowel hypomotility and small intestinal bacterial overgrowth, which cause malabsorption and malnutrition, ultimately contributing to the 50% mortality rate. Fecal incontinence is a common symptom of SSc that can lead to depression. SSc patients may suffer from gastrointestinal complications that can negatively impact their quality of life on a daily basis. Multidisciplinary approaches are necessary for systematically managing gastrointestinal complications associated with SSc. A prospective study should focus on developing targeted therapies to improve recovery patterns and prognosis in cases of SSc. This article summarizes the epidemiology, commonly reported clinical manifestations, complications, and available treatments for treating GI pathology in SSc patients.

How to Recognize and Treat Small Intestinal Bacterial Overgrowth?

Small Intestinal Bacterial Overgrowth (SIBO) is a form of dysbiosis that involves increased bacterial colonization of the small intestine with some of the bacteria more characteristic of the colon microbiota. The prevalence of SIBO over recent decades has been estimated to range from 2.5 to 22% (depending on the source) and to increase with age and among individuals with comorbidities. Recently, an increase in the number of diagnosed SIBO cases has been observed, which is primarily due to the availability of noninvasive breath tests that facilitate the diagnostic process. However, SIBO is still both a diagnostic and a therapeutic problem. This review presents the pathophysiology, manifestations, diagnostics, and recommended management of SIBO.

Dietary management of adults with IBD - the emerging role of dietary therapy

Historically, dietitians played a minor part in the management of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis. Patients were commonly referred for consequences of uncontrolled disease, such as malnutrition and bowel obstruction risk. Today, dietitians are fundamental members of the multidisciplinary IBD team, from educating on the role of diet at diagnosis and throughout the lifespan of a patient with IBD to guiding primary induction therapy. This aspect is reflected in published guidelines for IBD management, which previously placed diet as only a minor factor, but now have diet-specific publications. This Review describes a four-step approach in a dietitian's assessment and management of diet in patients with IBD: (1) identifying and correcting nutritional gaps and dietary imbalances; (2) considering diet to treat active disease with the use of exclusive enteral nutrition (EEN) or emerging diets that could replace EEN; (3) using therapeutic diets to control existing complications of IBD, such as reduced fibre to prevent bowel obstruction in stricturing disease or a fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet to manage co-existing functional gut symptoms; and (4) considering the role of diet in preventing IBD development in high-risk populations.

Distinctive Clinical Correlates of Small Intestinal Bacterial Overgrowth with Methanogens

BACKGROUND AND AIMS

Most patients with small intestinal bacterial overgrowth (SIBO) produce hydrogen by fermentation of dietary carbohydrates; however, ∼30% of patients with SIBO are colonized with Archaea, anaerobic organisms that produce methane. SIBO is associated with a plethora of symptoms and conditions, but their diagnostic significance is unclear. We aimed to determine if specific symptoms and conditions are associated with methanogenic SIBO.

METHODS

This study received institutional review board approval (IRB00059873). In this retrospective cross-sectional study, we queried a database of glucose breath tests conducted for suspected SIBO at our tertiary care medical center, which included data on the presence or absence of gastrointestinal symptoms and conditions often associated with SIBO. All patients had undergone a standardized breath testing protocol.

RESULTS

In a cohort of 1461 patients, 33.1% were SIBO positive; of these, 49.8% produced only hydrogen, 38.8% produced only methane, and 11.4% produced both gases. The following factors distinguished patients with hydrogen-producing SIBO, but not methanogenic SIBO, from SIBO-negative patients: vitamin B₁₂ deficiency (odds ratio, 1.44; confidence interval [CI], 1.01-2.06; P = .046), Roux-en-Y gastric bypass (odds ratio, 2.14; CI, 1.09-4.18; P = .027), cholecystectomy (odds ratio, 1.42; CI, 1.06-1.91; P = .020), and diabetes (odds ratio, 1.59; CI, 1.13-2.24; P = .008). The absence of vitamin B₁₂ deficiency was the sole discriminating factor between methanogenic and hydrogenic SIBO (odds ratio, 0.57; CI, 0.34-0.97; P = .038).

CONCLUSIONS

Patients with SIBO caused by methane-producing Archaea display a different spectrum of associated symptoms and clinical conditions compared with patients with SIBO caused by hydrogen-producing bacteria, particularly a lower incidence of vitamin B₁₂ deficiency.

Severe small intestinal bacterial overgrowth syndrome after jejunal feeding requiring surgical intervention: a case report and review of the literature

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) is a condition of unknown prevalence characterized by an excessive amount of bacteria in the small bowel, typically resulting in vague gastrointestinal symptoms with bloating being most commonly reported. Here we describe a severe case of SIBO leading to small bowel necrosis requiring surgical intervention.

CASE PRESENTATION

A 55-year-old Hispanic female with gastric outlet obstruction secondary to a newly diagnosed gastric adenocarcinoma, receiving neoadjuvant chemotherapy, developed bloody gastrostomy output and rapidly progressing nausea and abdominal distention 3 days after jejunostomy tube placement and initiation of jejunal enteral nutrition. Imaging revealed diffuse pneumatosis and portal venous gas. Surgical exploration confirmed segmental bowel necrosis requiring resection. Histologic findings were consistent with SIBO.

CONCLUSIONS

Presentation of severe SIBO in the setting of intestinal stasis secondary to gastric outlet after initiation of enteral feeds is a rare phenomenon. Early recognition and diagnosis of SIBO is critical in minimizing patient morbidity and mortality.

Efficacy of a Product Containing Xyloglucan and Pea Protein on Intestinal Barrier Function in a Partial Restraint Stress Animal Model

Functional abdominal bloating and distension (FABD) are common and frequent symptoms in patients with pre-existing gastrointestinal (GI) disorders. FABD is characterized by recurrent abdominal fullness and bloating. The pathophysiology of FABD is still unclear. However, the plausible mechanisms involved are small intestinal bacterial overgrowth (SIBO), imbalance of gut microbiota, visceral hypersensitivity, intestinal permeability alteration, and disruption of intestinal barrier function. Thus, the creation of a barrier on the wall of the intestine could represent an alternative therapeutic strategy to prevent FABD. This study aimed to investigate the effect of two natural substances, Xyloglucan (XG) and Pea-protein (PP), known for their mucosal-protective properties, in an in vivo model of Partial restraint-stress (PRS). Our results showed that the pre-treatment with a product containing XG and PP in stressed-rats was able to reduce the number of abdominal contractions and visceral hypersensitivity. Moreover, XG and PP were able to reduce intestinal permeability alteration, restoring tight-junctions (TJs) expression and decreased the lactulose–mannitol ratio, a quantitative marker used to measure intestinal permeability, compared to PRS-group. In conclusion, the data obtained revealed that the product containing XG and PP was able to restore the normal intestinal-barrier function; therefore, it could be considered a therapeutic strategy to manage FABD.

The prevalence of small intestinal bacterial overgrowth in diabetes mellitus: a systematic review and meta-analysis

OBJECTIVE

We conducted this systematic review and meta-analysis to estimate the prevalence of SIBO in diabetic patients and to determine the association between SIBO and diabetes.

METHODS

A comprehensive literature search of the PubMed, Cochrane Library and EMBASE databases from inception to June 2021 was conducted for studies correlating SIBO with diabetes. Studies were screened, and relevant data were extracted and analysed. The pooled prevalence of SIBO among diabetic patients and the odds ratio of SIBO among diabetic patients compared with controls were calculated.

RESULTS

Fourteen studies including 1417 diabetic patients and 649 controls met the inclusion criteria. The pooled prevalence of SIBO in diabetes was 29% (95% CI 20-39%). The odds ratio of SIBO in diabetic patients was 2.91 (95% CI 0.82-10.32, p=0.1) compared with controls. Subgroup analyses showed that the prevalence of SIBO in diabetes was higher in studies using jejunal aspirate culture for diagnosis (39%, 95% CI 12-66%) than in those using the lactulose breath test (31%, 95% CI 18-43%) or glucose breath test (29%, 95% CI 14-43%). The prevalence of SIBO in diabetes was higher in studies conducted in Western countries (35%, 95% CI 21-49%) than in those conducted in Eastern countries (24%, 95% CI 14-34%), and the prevalence of SIBO in type 1 diabetes (25%, 95% CI 14%-36%) was not significantly different from that in type 2 diabetes (30%, 95% CI 13%-47%).

CONCLUSIONS

Twenty-nine percent of diabetic patients tested positive for SIBO, and the risk of SIBO in diabetic patients was 2.91 times higher than that in patients without diabetes. Diabetes could be a predisposing factor for the development of SIBO, especially among patients diagnosed by jejunal aspirate culture or those in Western populations.

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.

Association of small intestinal bacterial overgrowth with nonalcoholic fatty liver disease in children: A meta-analysis

It has been suggested that small intestinal bacterial overgrowth (SIBO) could cause nonalcoholic fatty liver disease (NAFLD), but this association was not examined in children by meta-analysis. This meta-analysis aimed to determine the association between SIBO and NAFLD in children. The electronic databases PubMed, Embase, and Cochrane Library were searched for studies published before April 22, 2021. The outcome was the association between SIBO and NAFLD. Three studies and 205 children were included. All three studies reported the association between SIBO and NAFLD. Children with SIBO were more likely to have NAFLD (odds ratio = 5.27, 95% confidence interval (CI): 1.66-16.68, P<0.001; I2 = 63.5%, Pheterogeneity = 0.065). When directly pooling the reported relative risks (RR) from two studies, children with NAFLD had an over 2-fold increased relative risk of developing SIBO (RR = 2.17, 05%CI: 1.66-2.82, P<0.001; I2 = 0.0%, Pheterogeneity = 0.837). This meta-analysis reports a possible association between SIBO and NAFLD in children.

Small Intestinal Bacterial Overgrowth as Potential Therapeutic Target in Parkinson's Disease

Increasing evidence suggests that the gut microbiota and the brain are closely connected via the so-called gut–brain axis. Small intestinal bacterial overgrowth (SIBO) is a gut dysbiosis in which the small intestine is abundantly colonized by bacteria that are typically found in the colon. Though not a disease, it may result in intestinal symptoms caused by the accumulation of microbial gases in the intestine. Intestinal inflammation, malabsorption and vitamin imbalances may also develop. SIBO can be eradicated by one or several courses of antibiotics but reappears if the predisposing condition persists. Parkinson’s disease (PD) is a common neurodegenerative proteinopathy for which disease modifying interventions are not available. Sporadic forms may start in the gut years before the development of clinical features. Increased gastrointestinal transit time is present in most people with PD early during the course of the disease, predisposing to gut dysbiosis, including SIBO. The role that gut dysbiosis may play in the etiopathogenesis of PD is not fully understood yet. Here, we discuss the possibility that SIBO could contribute to the progression of PD, by promoting or preventing neurodegeneration, thus being a potential target for treatments aiming at slowing down the progression of PD. The direct symptomatic impact of SIBO and its impact on symptomatic medication are also briefly discussed.

European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus

Introduction

Measurement of breath hydrogen (H₂) and methane (CH₄) excretion after ingestion of test‐carbohydrates is used for different diagnostic purposes. There is a lack of standardization among centers performing these tests and this, together with recent technical developments and evidence from clinical studies, highlight the need for a European guideline.

Methods

This consensus‐based clinical practice guideline defines the clinical indications, performance, and interpretation of H₂‐CH₄‐breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 44 experts from 18 European countries. Eighty eight statements and recommendations were drafted based on a review of the literature. Consensus (≥80% agreement) was reached for 82. Quality of evidence was evaluated using validated criteria.

Results

The guideline incorporates new insights into the role of symptom assessment to diagnose carbohydrate (e.g., lactose) intolerances and recommends that breath tests for carbohydrate malabsorption require additional validated concurrent symptom evaluation to establish carbohydrate intolerance. Regarding the use of breath tests for the evaluation of oro‐cecal transit time and suspected small bowel bacterial overgrowth, this guideline highlights confounding factors associated with the interpretation of H₂‐CH₄‐breath tests in these indications and recommends approaches to mitigate these issues.

Conclusion

This clinical practice guideline should facilitate pan‐European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, it identifies areas of future research needs to clarify diagnostic and therapeutic approaches.

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.

The effectiveness of rotating versus single course antibiotics for small intestinal bacterial overgrowth

BACKGROUND

Small intestinal bacterial overgrowth treatment is usually based on antibiotics with no guidelines available.

OBJECTIVE

This study aimed to investigate the efficacy of different antibiotics to treat small intestinal bacterial overgrowth.

METHODS

Consecutive patients referred to our tertiary center and diagnosed with intestinal bacterial overgrowth were retrospectively included. Patients were diagnosed using a 75 g glucose breath test. Patients were treated either with a single antibiotic (quinolone or azole) or rotating antibiotics (quinolone and azole, one after the other) for 10 consecutive days per month for 3 months. A negative glucose breath test after antibiotic treatment was considered as remission. Quality of life (GIQLI) and gastrointestinal severity (IBS-SSS) were assessed before and after antibiotic treatment. Symptomatic evaluation was realized in simple blind of glucose breath test result: patients were unaware of their results.

RESULTS

Between August 2005 and February 2020, 223 patients were included in the analysis (female 79.8%, mean age 50.2 ± 15.7 years). Remission was observed in 119 patients (53.4%) after one course of antibiotics and was more frequent in patients receiving rotating antibiotics than in patients receiving a single antibiotic (70.0% vs. 50.8%, p = 0.050). Remission was associated with a significant improvement in quality of life (p = 0.035) and in bloating (p = 0.004).

CONCLUSION

In this study, the treatment of small intestinal bacterial overgrowth using rotating antibiotics was more effective than treatment using a single course of antibiotic. Remission was associated with improvement in both quality of life and bloating.

NONINVASIVE BREATH TESTS FOR DIAGNOSIS OF SIBO AND LACTOSE INTOLERANCE IN PATIENTS ON CHEMOTHERAPY TREATMENT FOR COLORECTAL AND GASTRIC CÂNCER

BACKGROUND

Worldwide, colorectal cancer (CRC) and gastric cancer (GC) are the third and the fifth most prevalent, respectively. Diarrhea is a common symptom in patients on chemotherapy or radiotherapy treatment and can reduce treatment tolerance. Surgical resections and chemotherapy change the intestinal microbiota that can lead to lactose intolerance, small intestinal bacterial overgrowth (SIBO).

OBJECTIVE

The aim of the study was to evaluate the frequency of diarrhea in patients with CRC and GC on chemotherapy with SIBO or intolerance of lactose.

METHODS

This is a descriptive and observational study with patients of both sexes, over 18 years old, in treatment in the Gastro-Oncology outpatient clinic of the Federal University of São Paulo. Patients with a confirmed diagnosis of CRC or GC during chemotherapy treatment were included. To detect bacterial overgrowth and lactose intolerance, breath hydrogen test with lactulose and lactose was done. Number and aspects of the evacuations and toxicity degree were collected. For the nutritional assessment, weight and height were performed to calculate the BMI. and the Patient Generated Subjective Global Assessment (PG-SGA).

RESULTS

A total of 33 patients were included, 29 with CRC and 3 with GC. Most of them were male (57.57%), mean age of 60.03±10.01 years and in chemotherapy with fluoropyrimidine and oxaliplatin (54.5%). Diarrhea was present in 57.6% and 30.3% had toxicity grade 2. According to the BMI, 78.9% were eutrophics, obese or overweight, but according to PG-SGA, 84.9% had moderate or severe nutritional risk grade. Between patients, 45% had lactose intolerance and 9% SIBO. Diarrhea grade 2-3 was observed in 66.6% of patients with SIBO and 66.7% of that with lactose intolerance. No statistical difference was observed between patients with SIBO or lactose intolerance and grade of diarrhea.

CONCLUSION

Diarrhea was a frequent symptom in chemotherapy patients with gastric or colorectal cancer independent of the presence of SIBO or lactose intolerance. Surgery and chemotherapy treatment impacted in the intestinal habit of patients. Diagnosis of other causes of diarrhea may contribute to a better tolerance to treatment and quality of life.

How the North American Consensus Protocol Affects the Performance of Glucose Breath Testing for Bacterial Overgrowth Versus a Traditional Method

INTRODUCTION

The North American Consensus guidelines for glucose breath testing (GBT) for small intestinal bacterial overgrowth (SIBO) incorporated changes in glucose dosing and diagnostic cutoffs. We compared GBT positivity based on hydrogen and methane excretion and quantified symptoms during performance of the North American vs older modified Rome Consensus protocols.

METHODS

GBT was performed using the North American protocol (75 g glucose, cutoffs >20 parts per million [ppm] hydrogen increase after glucose and >10 ppm methane anytime) in 3,102 patients vs modified Rome protocol (50 g glucose, >12 ppm hydrogen and methane increases after glucose) in 3,193 patients with suspected SIBO.

RESULTS

Positive GBT were more common with the North American vs modified Rome protocol (39.5% vs 29.7%, P < 0.001). Overall percentages with GBT positivity using methane criteria were greater and hydrogen criteria lower with the North American protocol (P < 0.001). Peak methane levels were higher for the North American protocol (P < 0.001). Times to peak hydrogen and methane production were not different between protocols. With the North American protocol, gastrointestinal and extraintestinal symptoms were more prevalent after glucose with both positive and negative GBT (P < 0.04) and greater numbers of symptoms (P < 0.001) were reported.

DISCUSSION

GBT performed using the North American Consensus protocol was more often positive for SIBO vs the modified Rome protocol because of more prevalent positive methane excretion. Symptoms during testing were greater with the North American protocol. Implications of these observations on determining breath test positivity and antibiotic decisions for SIBO await future prospective testing.

Mechanisms of Food-Induced Symptom Induction and Dietary Management in Functional Dyspepsia

Functional dyspepsia (FD) is a common disorder of gut-brain interaction, characterised by upper gastrointestinal symptom profiles that differentiate FD from the irritable bowel syndrome (IBS), although the two conditions often co-exist. Despite food and eating being implicated in FD symptom induction, evidence-based guidance for dietetic management of FD is limited. The aim of this narrative review is to collate the possible mechanisms for eating-induced and food-related symptoms of FD for stratification of dietetic management. Specific carbohydrates, proteins and fats, or foods high in these macronutrients have all been reported as influencing FD symptom induction, with removal of 'trigger' foods or nutrients shown to alleviate symptoms. Food additives and natural food chemicals have also been implicated, but there is a lack of convincing evidence. Emerging evidence suggests the gastrointestinal microbiota is the primary interface between food and symptom induction in FD, and is therefore a research direction that warrants substantial attention. Objective markers of FD, along with more sensitive and specific dietary assessment tools will contribute to progressing towards evidence-based dietetic management of FD.

Small intestinal bacterial overgrowth in spinal cord injury patients

AIM

Spinal cord injury (SCI) patients may have intestinal dysmotility and digestive symptoms that are associated with small intestinal bacterial overgrowth (SIBO). The aim of this study is to describe the prevalence of SIBO in SCI patients and the risk factors of its development.

METHODS

Twenty-nine consecutive SCI patients were studied (10 women/19 men; mean age 47 years), 16 with subacute injuries (<9 months) and 13 with chronic injuries (>1 year). Nine patients were affected by tetraplegia and 15 by paraplegia. Each patient underwent a glucose breath test according to the North American Consensus and the presence of abdominal symptoms was evaluated during the test. The results were compared with 15 non-neurological patients with SIBO.

RESULTS

Six patients tested positive for SIBO (21%), all of them affected by SCI in the subacute phase, 6/16 vs. 0/13 in the chronic phase (P<.05) and the majority with tetraplegia, 5/9 vs. 1/19 with paraplegia (P<.05). No statistically significant relationship was found with other clinical characteristics. All the tests were positive for methane or mixed (methane and hydrogen), while only 67% of the controls had methane-predominant production (P>.05).

CONCLUSION

SCI patients can develop SIBO, more frequently in the subacute phase and in tetraplegic patients, highlighting a high production of methane. This complication should be considered in neurogenic bowel management.

The interplay between gastrointestinal and cardiovascular diseases: a narrative review focusing on the clinical perspective

Both cardiovascular and gastrointestinal disorders represent considerable health burden on community clinics and hospitals with overwhelming economic cost. An overlap in the occurrence of these disorders is encountered in daily practice. Both affect each other in bidirectional manner through several mechanisms including altered hemodynamics, systemic inflammation, bacterial overgrowth and interactions and adverse effects of medications. In addition, to the known overlap in the symptoms occurrence of upper gastrointestinal tract diseases and cardiovascular diseases (CVDs). Awareness of this interplay and its clinical manifestations optimizes patient management, and could prevent catastrophic consequences and even save lives. In this review, we highlighted the clinical aspects of this bidirectional association between gastrointestinal and CVDs aiming to shed light on this topic and improve patients' care.

Gut Microbiota Modulation and Fecal Transplantation: An Overview on Innovative Strategies for Hepatic Encephalopathy Treatment

Hepatic encephalopathy (HE) is a major complication of cirrhosis, which is associated with gut microbial composition and functional alterations. Current treatments largely focus on gut microbiota using lactulose, rifaximin and other agents. However, despite these treatments, patients with HE have a high rate of readmission, morbidity and cognitive impairment. Fecal microbiota transplant (FMT) involves introduction of a donor microbiota into a recipient and is currently mainly used for recurrent C. difficile infection (rCDI). The role of FMT in cirrhosis and HE is evolving. There have been two randomized clinical trials (RCT) and several case reports/series in cirrhosis. Both RCTs were safety-focused phase 1 trials. One involved pre-FMT antibiotics and FMT enema versus standard of care, while the other involved 15 FMT capsules versus placebo without pre-FMT antibiotics. There was evidence of safety in both trials and the FMT group demonstrated reduction in hospitalizations compared to the non-FMT group. Changes in microbial function centered around short-chain fatty acids, bile acids and brain function showed improvement in the FMT groups. Long-term follow-up demonstrated continued safety and reduction in the antibiotic-resistance gene carriage. However, larger trials of FMT in HE are needed that can refine the dose, duration and route of FMT administration.

Alternative Treatment Approaches to Small Intestinal Bacterial Overgrowth: A Systematic Review

Background: Broad-spectrum antibiotics are the first-line treatment for small intestinal bacterial overgrowth (SIBO). However, many antibiotics have a considerable side-effect profile and SIBO commonly reoccurs after successful eradication with antibiotics. Alternative therapies such as probiotics, therapeutic diets, and herbal medicines have been used to individualize SIBO management, particularly in recalcitrant cases. Objectives: The objective of this review is to evaluate the role of alternative therapies in SIBO treatment. Data Sources: EMBASE, MEDLINE, and the Cochrane Central Register were systematically searched for clinical studies evaluating alternative therapies in the management of SIBO. Study Eligibility Criteria: Human studies in which an alternative intervention was used to treat SIBO were included. Alternative interventions were defined as an intervention that included a probiotic supplement, herbal preparation, or a dietary change. Randomized controlled trials (RCTs), nonrandomized clinical trials with or without a control, and crossover studies were included. Study Appraisal: The following information was extracted from the selected studies: study type, study participants, SIBO subtype, intervention, comparison, outcome measures, relevant results, relevant side effects, and Jadad score. Results: Eight studies met inclusion criteria. The studies evaluated probiotics (n = 5), therapeutic diet (n = 1), and herbal medicines (n = 2). Among these studies, there were four RCTs, two open-label single-arm studies, one randomized, double-blind crossover study, and one two-arm open-label study with crossover. Main results are summarized. Limitations: There may be studies not captured by the defined search criteria. Additionally, studies used different methodologies in both breath testing and measurement of clinical symptoms, making it difficult to draw conclusions on SIBO eradication and symptom improvement across studies. Conclusions and Implications: Our findings suggest preliminary evidence for a role of alternative therapies in the treatment of SIBO. However, robust clinical trials are generally lacking. Existing studies tend to be small and lack standardized formulations of treatment. Breath testing protocols and clinical symptom measurement greatly varied between studies. Large-scale, randomized, placebo-controlled trials are needed to further evaluate the best way to utilize alternative therapies in the treatment of SIBO.

PREVALENCE AND FACTORS ASSOCIATED WITH SMALL INTESTINAL BACTERIAL OVERGROWTH IN PATIENTS WITH CROHN'S DISEASE: A RETROSPECTIVE STUDY AT A REFERRAL CENTER

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) appears to be common in patients with Crohn's disease (CD). The rate of SIBO has been estimated at 25%-88% in this setting. However, different demographic, socioeconomic, and disease-related factors may exist between South American and North American or European populations that may limit the generalization of these findings, as the data are mainly derived from North American or European studies.

OBJECTIVE

We studied the prevalence and predictors of SIBO in CD outpatients.

METHODS

In this retrospective study, between June 2011 and June 2016, the medical records of 110 CD patients were assessed for presence of SIBO using the H2/CH4 glucose breath test. Univariate analysis was performed to investigate the potential association between SIBO and demographic, disease-related data, systemic markers of inflammation (C-reactive protein and erythrocyte sedimentation rate).

RESULTS

The SIBO rate was high in CD patients (30%). Patients with and without SIBO were comparable according to demographics, systemic inflammatory biomarkers, and disease characteristics, except to the stricturing phenotype more common in the SIBO-positive CD patients (48.5% vs 19.5%, P=0.001).

CONCLUSION

In Brazilian CD patients, SIBO is a highly prevalent condition. Stricturing phenotype demonstrated association with SIBO. An individualized screening plan followed by the timely treatment for SIBO should be carried out as part of quality of care improvement in CD individuals.

Breath Test Gas Patterns in Inflammatory Bowel Disease with Concomitant Irritable Bowel Syndrome-Like Symptoms: A Controlled Large-Scale Database Linkage Analysis

INTRODUCTION

Breath testing (BT) has gained interest for diagnosing small intestinal bacterial overgrowth (SIBO) in IBD patients with irritable bowel syndrome (IBS) overlap. We aim to characterize the rate of SIBO and BT gas patterns in IBD patients with IBS-like symptoms compared to non-IBD patients.

METHODS

A database of 14,847 consecutive lactulose BTs was developed from patients with IBS-like symptoms between November 2005 and October 2013. BTs were classified as normal, H₂ predominant, CH₄ predominant, and flatline based on criteria established from the literature. BT data linkage with electronic health records and chart review identified IBD patients along with disease phenotype, location, severity, and antibiotic response. Poisson loglinear model evaluated differences in gas patterns between the two groups.

RESULTS

After excluding patients with repeat breath tests, we identified 486 IBD and 10,505 non-IBD patients with at least one BT. Positive BT was present in 57% (n = 264) of IBD patients. Crohn's disease (odds ratio (OR) 0.21, [95% confidence interval (CI) 0.11-0.38]) and ulcerative colitis (OR 0.39, [95% CI 0.22-0.70]) patients were less likely to produce excess CH₄. IBD patients were more likely to have flatline BT (OR 1.82, [95% CI 1.20-2.77]). In IBD patients with SIBO, 57% improved symptomatically with antibiotics.

CONCLUSION

In a cohort of IBD patients with IBS-like symptoms, a high rate of patients had positive BT and symptomatic improvement with antibiotics. In IBD, methanogenesis is suppressed and flatline BT is more frequent, suggesting excess hydrogenotrophic bacteria. These findings suggest methanogenic and hydrogenotrophic microorganisms as potential targets for microbiome-driven biomarkers and therapies.

Bariatric Surgery and Its Complications in Inflammatory Bowel Disease Patients

Recent data have suggested that bariatric procedures, especially laparoscopic sleeve gastrectomy (SG), are safe and effective weight loss measures in patients with inflammatory bowel disease (IBD). But most of the studies have looked at short-term outcomes, and there is a general lack of awareness of underlying disease processes and baseline comorbidities in IBD patients undergoing bariatric procedures. Postbariatric issues in IBD patients including diarrhea from dumping syndrome, choleretic diarrhea, a high prevalence of small intestinal bacterial overgrowth, gastroesophageal reflux disease, Barrett's esophagus, stomal ulcerations, stenosis, and renal and gallstones can complicate the natural history of IBD. This could lead to unnecessary hospitalizations, change of medical therapy, and poor surgical and quality of life outcomes. In this review, we will discuss major complications after common bariatric procedures (SG, Roux-en-Y gastric bypass, and gastric banding) and suggest possible management 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.

Diagnostic Utility of Carbohydrate Breath Tests for SIBO, Fructose, and Lactose Intolerance

BACKGROUND

Unexplained bloating, gas, and pain are common symptoms. If routine tests are negative, such patients are often labeled as irritable bowel syndrome.

AIMS

To determine the diagnostic utility of breath tests that assess for small intestinal bacterial overgrowth (SIBO), fructose or lactose intolerance, and the predictive value of symptoms.

METHODS

Patients with gas, bloating, diarrhea, abdominal pain (≥ 6 months), and negative endoscopy and radiology tests were assessed with symptom questionnaires, glucose (75 g), fructose (25 g), or lactose (25 g) breath tests. Breath tests were categorized as positive when H₂ (≥ 20 ppm) or CH₄ (≥ 15 ppm) increased above baseline values or as hypersensitive when symptoms changed significantly without rise in H₂/CH₄ or as negative.

RESULTS

1230 patients (females = 878) underwent 2236 breath tests. The prevalence of SIBO was 33% (294/883), fructose intolerance was 34% (262/763), and lactose intolerance was 44% (260/590). Hypersensitivity was found in 16% and 9%, respectively, during fructose and lactose breath tests. Although gas (89%), abdominal pain (82%), and bloating (82%) were highly prevalent, pretest symptoms or their severity did not predict an abnormal breath test, but symptoms during the breath test facilitated diagnosis of SIBO, fructose, and lactose intolerance and hypersensitivity.

CONCLUSIONS

Approximately 45% of patients with unexplained gas and bloating had SIBO, fructose, or lactose intolerance; another 9-16% had visceral hypersensitivity. Pretest symptoms were poor predictors, but symptoms during the breath tests were useful. Breath tests are safe, provide significant diagnostic yield, and could be useful in routine gastroenterology practice.

When is parenteral nutrition indicated in the hospitalized, acutely ill patient?

PURPOSE OF REVIEW

The current review discusses current practices regarding appropriate indications for parenteral nutrition in acutely ill hospitalized patients. We address-specific indications for parenteral nutrition in the perioperative period, and in inflammatory bowel disease, oncology, hepatobiliary, critical care and end-stage renal disease patients.

RECENT FINDINGS

Acutely ill hospitalized patients can develop intestinal failure requiring parenteral nutrition. Recent studies have provided insight into the main indications. The most common indications for inpatient parenteral nutrition include postsurgical complications, including prolonged ileus, sepsis, fistula and leaks, and bowel obstruction, predominantly malignant. Severe or complicated inflammatory bowel disease and cancer treatment-related mucosal enteropathies (mucositis, enterocolitis, gut graft-versus-host disease) are the next commonest indications. Less frequent indications are primary motility disorders and inability to secure enteral access for enteral nutrition. Gastrointestinal failure of the intensive care patient is a separate entity resulting from multiple mechanisms, including an enteropathy and dysmotility.

SUMMARY

Despite the wider availability of nutrition support teams, use of parenteral nutrition is not without risk. The risks and benefits of parenteral nutrition in the acute setting need to be carefully considered even when it is indicated.

Breath Tests for the Non-invasive Diagnosis of Small Intestinal Bacterial Overgrowth: A Systematic Review With Meta-analysis

BACKGROUND/AIMS

Small intestinal bacterial overgrowth (SIBO) diagnosis is usually based on non-invasive breath tests (BTs), namely lactulose BT (LBT) and glucose BT (GBT). However, divergent opinions and problems of parameter standardization are still controversial aspects. We aim to perform a meta-analysis to analyze diagnostic performance of LBT/GBT for SIBO diagnosis.

METHODS

We searched in main literature databases articles in which SIBO diagnosis was achieved by LBT/GBT in comparison to jejunal aspirate culture (reference gold standard). We calculated pooled sensitivity, specificity, positive, and negative likelihood ratios and diagnostic odd ratios. Summary receiver operating characteristic curves were drawn and pooled areas under the curve were calculated.

RESULTS

We selected 14 studies. Pooled sensitivity of LBT and GBT was 42.0% and 54.5%, respectively. Pooled specificity of LBT and GBT was 70.6% and 83.2%, respectively. When delta over baseline cut-off > 20 H₂ parts per million (ppm) was used, GBT sensitivity and specificity were 47.3% and 80.9%; when the cutoff was other than and lower than > 20 ppm, sensitivity and specificity were 61.7% and 86.0%. In patients with abdominal surgery history, pooled GBT sensitivity and specificity gave the impression of having a better performance (81.7% and 78.8%) compared to subjects without any SIBO predisposing condition (sensitivity = 40.6% and specificity = 84.0%).

CONCLUSIONS

GBT seems to work better than LBT. A cut-off of delta H2 expired other than and lower than > 20 ppm shows a slightly better result than > 20 ppm. BTs demonstrate the best effectiveness in patients with surgical reconstructions of gastrointestinal tract.

Clinical Management of the Microbiome in Irritable Bowel Syndrome

Background

A growing body of evidence suggests that dysbiosis contributes to the onset and symptomatology of irritable bowel syndrome (IBS) and other functional bowel disorders. Changes to the gastrointestinal microbiome may contribute to the underlying pathophysiology of IBS.

Methods

The present review summarizes the potential effects of microbiome changes on GI transit, intestinal barrier function, immune dysregulation and inflammation, gut–brain interactions and neuropsychiatric function.

Results

A multimodal approach to IBS management is recommended in accordance with current Canadian guidelines. Pharmacologic treatments are advised to target the presumed underlying pathophysiological mechanism, such as dysregulation of GI transit, peristalsis, intestinal barrier function and pain signalling. The management plan for IBS may also include treatments directed at dysbiosis, including dietary modification and use of probiotics, which may promote the growth of beneficial bacteria, affect intestinal gas production and modulate the immune response; and the administration of periodic short courses of a nonsystemic antibiotic such as rifaximin, which may re-establish microbiota diversity and improve IBS symptoms.

Conclusion

Dysregulated host–microbiome interactions are complex and the use of microbiome-directed therapies will necessarily be empiric in individual patients. A management algorithm comprising microbiome- and nonmicrobiome-directed therapies is proposed.

Usefulness of the hydrogen breath test in patients with functional dyspepsia

Introduction

The pathogenesis of functional dyspepsia is complex and not well understood. Therefore, in this disease there should be considered involvement of different pathogenic factors, including intestinal bacteria.

Aim

To evaluate the results of the hydrogen breath test in relation to the clinical picture of functional dyspepsia.

Material and methods

The study included 40 healthy subjects (group I), 72 patients with postprandial distress syndrome (PDS, group II), and 84 patients with epigastric pain syndrome (EPS, group III). The diagnosis of functional dyspepsia was based on Rome Criteria IV. The urea breath test (13C-UBT) and lactulose hydrogen breath test (LHBT) were performed in all subjects. Patients with a positive urea breath test were excluded from the study. Patients with a positive LHBT test were assigned to antibiotic therapy (1200 mg daily for 14 days). Before treatment and 6 weeks after the end of antibiotic therapy the LHBT was performed, and severity of dyspeptic symptoms was assessed using a 10-points visual analogue scale.

Results

A positive LHBT test was found in 35 (48.6%) patients in the group with PDS, and in 40 (47.6%) patients with EPS (p > 0.05). A positive correlation between the results of the LHBT test and severity of dyspeptic symptoms was found in both group (p < 0.001). After treatment with rifaximin the mean LHBT result and the index of severity of dyspeptic complaints were significantly decreased (p < 0.001).

Conclusions

Quantitative and/or qualitative changes in the gut microbiota may be the cause of functional dyspepsia.

Review of the management of diarrhea syndrome after a bariatric surgery

Obesity is a prevalent health problem in our population. Bariatric surgery is the indicated treatment for severe cases. It is very effective (together with an adequate lifestyle modification) but it is also associated with frequent adverse events. One of the most frequent and disturbing adverse event is diarrhea. Diarrhea after bariatric surgery may be secondary to multiple causes and the physiopathogenic mechanisms may depend on the type of surgery performed. The most frequent diarrhea mechanisms are dumping syndrome, vagotomy, short bowel syndrome, carbohydrate malabsorption, protein malabsorption, alterations of the microbiota, Clostridium difficile infection, bacterial overgrowth, bile salt malabsorption, pancreatic insufficiency, endocrinological disorders, addictive disorders, and other digestive disorders not necessarily related to surgery.

Small intestinal bacterial overgrowth is associated with Diarrhea-predominant irritable bowel syndrome by increasing mainly Prevotella abundance

Objective: Diarrhea-predominant irritable bowel syndrome (IBS-D) is the main subtype of IBS, a chronic functional gastrointestinal disorder. Small intestinal bacterial overgrowth (SIBO), which is characterized by dysbiosis of the bowel, causes gastrointestinal symptoms quite similar to IBS-D. However, whether SIBO correlates with IBS-D and its further mechanism remain unknown.Materials and Methods: The study included 60 IBS-D patients that fulfilled Rome IV criteria and 60 healthy controls. All subjects were undergoing a lactose breath test (LBT) to diagnose SIBO. IBS-D patients were further assigned to negative SIBO (SIBO^-) subgroup and positive SIBO (SIBO⁺) subgroup to analyze the scores of symptoms and differences in the fecal microbiota.Results: The prevalence of SIBO in IBS-D patients was higher than that in healthy controls (51.7% vs. 16.7%, p ≤ .001). In addition, IBS-SSS in SIBO⁺ subgroup was significantly higher than SIBO^- subgroup (p = .015). The 16S rRNA analyses showed that composition and abundance of fecal microbiota were obviously different between the two subgroups. There was a remarkable increase in Prevotella in IBS-D patients, especially in IBS-D SIBO⁺ sufferers. Meanwhile, there were a moderately positive correlation of the abundance of Prevotella (rho = 0.458, p ≤ .001) with IBS-SSS.Conclusion: SIBO is associated with IBS-D, which may be related to alteration in the intestinal microbiota. These findings suggest the potent role of Prevotella in gastrointestinal symptoms between SIBO and IBS-D, thus provide a novel insight into the connection between SIBO and IBS-D.

Lactulose Breath Testing as a Predictor of Response to Rifaximin in Patients With Irritable Bowel Syndrome With Diarrhea

OBJECTIVES

The nonsystemic antibiotic rifaximin is indicated for irritable bowel syndrome with diarrhea (IBS-D) in adults; however, determinants of response remain unclear. The utility of lactulose breath testing (LBT) in predicting response to rifaximin was examined.

METHODS

Adults with IBS-D received open-label rifaximin 550 mg 3 times daily for 2 weeks, followed by a 4-week posttreatment assessment period. Thirteen centers prospectively participated in this substudy. LBT was conducted before (day 1) and after (day 14) therapy (breath samples obtained every 15 minutes; up to 240 minutes). Patient response (decrease from baseline of ≥30% in abdominal pain and ≥50% decrease in frequency of mushy/watery stool), symptom improvement, and the relationship of clinical outcomes to LBT results were assessed.

RESULTS

A total of 93 patients were included; 62 (66.7%) had positive baseline LBT results. Overall, 48.4% (45/93) of patients responded to rifaximin; of these, 59.7% (37/62) had a positive baseline LBT vs 25.8% (8/31) with a negative LBT (P = 0.002; odds ratio 4.3, 95% confidence interval, 1.5-12.7). Patients with a positive baseline LBT result experienced significantly greater improvement from baseline in 6 of 7 individual IBS symptoms. LBT results after rifaximin therapy did not correlate with clinical response in the 86 patients with evaluable breath tests (P = 0.21); however, patients whose LBT results normalized after rifaximin had the highest response rate of 76.5% (13/17).

DISCUSSION

A positive baseline LBT result predicted a higher likelihood of response to rifaximin in IBS-D, suggesting a gut microbiome modulatory mechanism of action for rifaximin.

Is small intestinal bacterial overgrowth a cause of hyperdynamic circulation in cirrhosis?

BACKGROUND/AIMS

Small intestinal bacterial overgrowth (SIBO) and hemodynamic changes are common in cirrhosis. We wanted to examine our hypothesis whether SIBO leads to hemodynamic changes in cirrhosis.

MATERIALS AND METHODS

A total of 50 patients with cirrhosis and 15 healthy controls were enrolled in a pilot prospective study. All participants underwent the lactulose hydrogen breath test for SIBO and echocardiography with a simultaneous assessment of blood pressure and heart rate. Cardiac output and systemic vascular resistance were calculated.

RESULTS

Study participants with SIBO had a lower systolic blood pressure and systemic vascular resistance compared to those without SIBO and to healthy controls (110.2±12.3 mmHg vs. 126.2±21.0 mmHg and 121.2±9.8 mmHg; p=0.005 and p=0.011, respectively; 1312±352 dyn•s•cm-5 vs. 1704±424 dyn•s•cm-5 and 1648±272 dyn•s•cm-5; p=0.001 and p=0.006, respectively), but a higher cardiac output (5.38±1.41 l/min vs. 4.52±1.03 l/min and 4.40±0.68 l/min; p=0.034 and p=0.041, respectively) and C-reactive protein (10.5[1.2-16.5] mg/l vs. 2.8[0.6-9.1] mg/l; p=0.028; no comparison with healthy controls). There were no significant differences between patients without SIBO and healthy controls with regard to systolic blood pressure (p=0.554), systemic vascular resistance (p=0.874), and cardiac output (p=0.795). SIBO was associated with vasodilation and hyperdynamic circulation in decompensated cirrhosis (p=0.002; p=0.012), but not in compensated cirrhosis (p=1.000; p=0.474).

CONCLUSIONS

SIBO is associated with hyperdynamic circulation and other hemodynamic changes in cirrhosis and may be a principal factor causing these through systemic inflammation.

Small intestinal bacterial overgrowth in children with intestinal failure on home parenteral nutrition

Background and Aim

Children with intestinal failure (IF) have abnormal intestinal anatomy, secretion, or motility, which impairs homeostatic mechanisms and can lead to small intestinal bacterial overgrowth (SIBO). We sought to describe clinical features at the time of clinically suspected SIBO by experienced clinicians in children with IF on home parenteral nutrition (PN), review specific challenges of diagnostic testing in this population, and describe potential new diagnostic surrogate markers.

Methods

A descriptive single‐center retrospective chart review was performed during all episodes of clinically suspected SIBO over 33 months. Information was recorded on clinical symptoms, and diagnostic tests performed.

Results

Of all patients on home PN, 71% (12/17) had at least one episode of clinically suspected SIBO (mean 1 episode/year, range 1–7); 50% of patients had short bowel syndrome (SBS), and 50% had non‐SBS IF. The average reported symptoms per episode were 1.9 (range 1–5). Children with SBS reported fewer symptoms per episode (1.5) than children with non‐SBS IF (2.3). Diarrhea was the most commonly reported symptom, particularly in children with SBS.

Conclusions

Children with IF on home PN are a high‐risk group for SIBO. Clinical features of SIBO vary depending on the cause of IF and may mimic symptoms of the underlying condition. Diagnostic tests have innate challenges in this group, and a strong index of clinical suspicion is paramount. Further research is recommended into potential new surrogate markers (urinary metabolite screen, gastric aspirate) for this diagnostically challenging population.

Reconstructive Surgery for Intestinal Failure

BACKGROUND

Intestinal failure (IF) in the adult is the result of a wide spectrum of disease. Acute mesenteric ischemia, postoperative short bowel due to a complicative course, and Crohn's disease are major causes of IF. Reconstructive surgery in the context of IF comprises a spectrum of procedures including stoma takedown, reversal of laparostomies, and closure of enteric fistulas.

METHODS

This article is based on a PubMed-based literature search and personal experience in adult patients with IF.

RESULTS

This review summarizes therapeutic options of reconstructive surgery in adult patients focusing on the main reasons of IF such as mesenteric ischemia, complicative previous surgery, and Crohn's disease. Indications and contraindications are discussed as well as the optimal time point of reconstructive surgery.

CONCLUSION

This overview summarizes surgical aspects in a special cohort of patients with a rare disease entity necessitating an interdisciplinary approach.