Elevated methane levels in small intestinal bacterial overgrowth suggests delayed small bowel and colonic transit

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.

Symptom Profile of Patients With Intestinal Methanogen Overgrowth: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Archaea constitute one of the main 3 domains of the tree of life, distinct from eukaryotes and bacteria. Excessive luminal loads of methanogenic archaea (intestinal methanogen overgrowth [IMO]) have been implicated in the pathophysiology of various diseases, including constipation. To elucidate the phenotypical presentation of IMO, we performed a systematic review and meta-analysis of the prevalence and severity of gastrointestinal symptoms in subjects with IMO as compared with subjects without IMO.

METHODS

Electronic databases, including OVID MEDLINE and Cochrane Database from inception until September 2023, were systematically searched. Prevalence rates, odds ratios (ORs), standardized mean difference (SMD), and 95% confidence intervals (CIs) of symptoms were calculated.

RESULTS

Nineteen studies were included (1293 patients with IMO and 3208 controls). Patients with IMO exhibited various gastrointestinal symptoms, including bloating (78%), constipation (51%), diarrhea (33%), abdominal pain (65%), nausea (30%), and flatulence (56%). Patients with IMO had a significantly higher prevalence of constipation as compared with controls (47% vs 38%; OR, 2.04; 95% CI, 1.48-2.83; P < .0001) along with lower prevalence of diarrhea (37% vs 52%; OR, 0.58; 95% CI, 0.37-0.90; P = .01) and nausea (32% vs 45%; OR, 0.75; 95% CI, 0.60-0.94; P = .01). Patients with IMO had higher severity of constipation (SMD, 0.77; 95% CI, 0.11-1.43; P = .02) and lower severity of diarrhea (SMD, -0.71; 95% CI, -1.39 to -0.03; P = .04). Significant heterogeneity was detected.

CONCLUSION

Patients with IMO exhibit a higher rate and severity of constipation along with lower rate and severity of diarrhea. The distinct phenotype of patients with IMO should be incorporated in patient-reported outcome measures and further correlated with mechanistic microbiome studies.

The relationship between small intestinal bacterial overgrowth and constipation in children - a comprehensive review

Small intestinal bacterial overgrowth (SIBO) is characterized by an increase in the bacterial population of the small intestine due to an imbalance between the amount of bacteria and the intestinal barrier. Pediatric SIBO presents with a wide spectrum of symptoms, ranging from mild gastrointestinal complaints to malabsorption or malnutrition. Breath tests are commonly used as noninvasive diagnostic tools for SIBO, but a standardized methodology is currently unavailable. Intestinal flora produces methane which slows intestinal transit and increases the contractile activity of small intestine. Emerging literature suggests a correlation between overgrowth of methanogenic bacteria in the intestines and constipation. Treatment of SIBO involves administration of antibacterial therapy in addition to management of underlying conditions and optimal dietary adjustments. However, research on antibiotic treatment for pediatric patients with constipation and SIBO is limited and has yielded conflicting results. In the current review, we summarize the state-of-the-art of the field and discuss previous treatment attempts and currently used regimens for SIBO patients with constipation, with a focus on pediatric populations.

Therapeutic Evaluation of Bifidobacterium animalis subsp. lactis MH-02 as an Adjunctive Treatment in Patients with Reflux Esophagitis: A Randomized, Double-Blind, Placebo-Controlled Trial

Proton pump inhibitors (PPIs) are currently routinely used for the treatment of reflux esophagitis (RE); however, with frequent symptom recurrence after discontinuation and limited clinical improvement in accompanying gastrointestinal symptoms. This study aims to explore the adjuvant therapeutic effect of Bifidobacterium supplement for RE patients. A total of 110 eligible RE patients were recruited and randomly assigned to the placebo and probiotic groups. All patients were treated with rabeprazole tablets and simultaneously received either Bifidobacterium animalis subsp. lactis MH-02 or placebo for 8 weeks. Patients who achieved clinical remission then entered the next 12 weeks of follow-up. RDQ, GSRS scores, and endoscopy were performed to assess clinical improvement, and changes in intestinal microbiota were analyzed with high-throughput sequencing. Our results revealed that MH-02 combined therapy demonstrated an earlier time to symptom resolution (50.98% vs. 30.61%, p = 0.044), a significant reduction in the GSRS score (p = 0.0007), and a longer mean time to relapse (p = 0.0013). In addition, high-throughput analyses showed that MH-02 combined therapy increased the α (p = 0.001) diversity of gut microbiota and altered microbial composition by beta diversity analysis, accompanied with significantly altered gut microbiota taxa at the genus level, where the abundance of some microbial genera including Bifidobacterium, Clostridium, and Blautia were increased, while the relative abundance of Streptococcus and Rothia were decreased (p < 0.05). Collectively, these results support the beneficial effects of MH-02 as a novel complementary strategy in RE routine treatment.

Non-invasive detection of renal disease biomarkers through breath analysis

Breath biomarkers are substances found in exhaled breath that can be used for non-invasive diagnosis and monitoring of medical conditions, including kidney disease. Detection techniques include mass spectrometry (MS), gas chromatography (GC), and electrochemical sensors. Biosensors, such as GC-MS or electronic nose (e-nose) devices, can be used to detect volatile organic compounds (VOCs) in exhaled breath associated with metabolic changes in the body, including the kidneys. E-nose devices could provide an early indication of potential kidney problems through the detection of VOCs associated with kidney dysfunction. This review discusses the sources of breath biomarkers for monitoring renal disease during dialysis and different biosensor approaches for detecting exhaled breath biomarkers. The future of using various types of biosensor-based real-time breathing diagnosis for renal failure is also discussed.

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.

The evolving role of methanogenic archaea in mammalian microbiomes

Methanogenic archaea (methanogens) represent a diverse group of microorganisms that inhabit various environmental and host-associated microbiomes. These organisms play an essential role in global carbon cycling given their ability to produce methane, a potent greenhouse gas, as a by-product of their energy production. Recent advances in culture-independent and -dependent studies have highlighted an increased prevalence of methanogens in the host-associated microbiome of diverse animal species. Moreover, there is increasing evidence that methanogens, and/or the methane they produce, may play a substantial role in human health and disease. This review addresses the expanding host-range and the emerging view of host-specific adaptations in methanogen biology and ecology, and the implications for host health and disease.

Intestinal flora in the constipation patients before versus after lactulose intervention

This study aimed to investigate the characteristics of intestinal flora in patients with chronic functional constipation before and after lactulose intervention. Twenty-nine patients with constipation in the treatment group received oral lactulose (15 mL/d) for a month. Twenty healthy subjects served as controls. Stool specimens were collected before and after lactulose treatment. Fecal bacteria were examined by 16SrRNA gene sequencing and bioinformatics analysis. After lactulose treatment, most bacteria in the constipation group, including Bifidobacteria, Bacillus cereus, Prevotella, Bacillus, Anaerostipes, Oribacterium, and Mogibacterium increased as compared to those in the healthy control group. Anaerotruncus declined in the healthy control group after lactulose treatment. Our study shows lactulose can increase the abundance of probiotics, optimize the intestinal microenvironment, and alleviate constipation.

Small Intestinal Bacterial Overgrowths and Intestinal Methanogen Overgrowths Breath Testing in a Real-Life French Cohort

INTRODUCTION

Breath testing has become a widely used tool to diagnose small intestinal bacterial overgrowths (SIBOs) and intestinal methanogen overgrowths (IMOs) in clinical settings. Owing to the heterogeneity in clinical manifestations and lack of standardization among centers performing breath testing, SIBO and IMO can be easily overlooked by the clinician. We studied the prevalence and symptoms of SIBO/IMO in French patients referred for breath testing after seeking medical advice.

METHODS

Breath test data and symptoms of 331 patients were assessed for SIBO/IMO using the H 2 /CH 4 lactulose breath test (LBT). Wilcoxon test or χ 2 test were used to compare patients with SIBO/IMO with patients without SIBO/IMO. LBT positive patients (H 2 +, CH 4 +, and CH 4 +/H 2 +) were compared using Kruskal-Wallis test for continuous data or χ 2 test for categorical data.

RESULTS

Among the 186 (68.1%) patients tested positive for an overgrowth with 40.3%, 47.3%, and 12.4% for H 2 +, CH 4 + and CH 4 +/H 2 +, respectively, the presence of diarrhea was significantly increased in hydrogen type overgrowths ( P < 0.001). No significant difference according to age, gender, and symptoms was associated with a positive test except for joint pain that was less prevalent among LBT positive patients ( P = 0.038). In 86.5% of IMOs, positivity with CH 4 values ≥10 ppm could be identified at baseline.

DISCUSSION

There are little discriminating symptoms that can help the clinician to identify patients likely to have a SIBO/IMO. However, SIBO/IMOs remain a common disorder widely underdiagnosed that need further studies to better apprehend functional bowel disorders.

Pros and Cons of Breath Testing for Small Intestinal Bacterial Overgrowth and Intestinal Methanogen Overgrowth

Breath testing is the most widely utilized modality to diagnose small intestinal bacterial overgrowth (SIBO) and/or intestinal methanogen overgrowth (IMO). Although SIBO can be diagnosed with small bowel aspiration and breath testing, IMO can only be diagnosed with breath testing in clinical practice. Breath testing can tailor antibiotic therapy and predict response to treatment; however, the test is limited by its indirect method of measurement and concerns about the variability of orocecal transit time. Like any clinical test, breath testing has inherent strengths and limitations, and results must be interpreted with consideration of the clinical context and influencing factors. Recent studies have demonstrated the expanding clinical utility of breath testing in the diagnosis, management, and prediction of treatment response in SIBO and particularly in IMO along with the identification of distinct breath test patterns such as flat-line and high baseline hydrogen. This article reviews the strengths and limitations of breath testing in diagnosing SIBO and IMO as well as its expanding utility in clinical practice.

Efficacies of prokinetics and rifaximin on the positivity of a glucose breath test in patients with functional dyspepsia: a randomized trial

BACKGROUND AND AIM

prokinetics could eradicate small intestinal bacterial overgrowth. This study aimed to evaluate the efficacy of mosapride, rifaximin and a combination of mosapride and rifaximin for the treatment of small intestinal bacterial overgrowth.

METHODS

we randomly assigned patients with functional dyspepsia diagnosed with small intestinal bacterial overgrowth in a 1:1:1 ratio to receive mosapride, rifaximin or a combination of both for two weeks. The hydrogen-methane glucose breath test and symptom questionnaire were surveyed before and after the treatment. Primary outcome was eradication rate of small intestinal bacterial overgrowth. Secondary outcomes were changes in the gas concentration, symptoms and safety.

RESULTS

the eradication rates were 17.2 % (5/29) for mosapride, 32.1 % (9/28) for rifaximin, and 34.6 % (9/26) for the combined groups, with no significant differences among the three groups. Total hydrogen concentration during the glucose breath test significantly decreased in the rifaximin group (p = 0.001). Total methane concentration significantly decreased in the rifaximin and combined groups (p = 0.005). Significant symptomatic improvements were observed in chest and abdominal discomfort with mosapride, in flatulence with rifaximin, and in chest discomfort with the combined groups. Adverse events were similar between the groups.

CONCLUSIONS

rifaximin has an advantage of reducing gas, whereas mosapride can help to decrease breath hydrogen concentration. Certain intestinal symptoms improved with mosapride alone or combined with rifaximin.

Asia-Pacific guidelines for managing functional dyspepsia overlapping with other gastrointestinal symptoms

Contemporary systems for the diagnosis and management gastrointestinal symptoms not attributable to organic diseases (Functional GI Disorders, FGID, now renamed Disorders of Gut-Brain Interaction, DGBI) seek to categorize patients into narrowly defined symptom-based sub-classes to enable targeted treatment of patient cohorts with similar underlying putative pathophysiology. However, an overlap of symptom categories frequently occurs and has a negative impact on treatment outcomes. There is a lack of guidance on their management. An Asian Pacific Association of Gastroenterology (APAGE) working group was set up to develop clinical practice guidelines for management of patients with functional dyspepsia (FD) who have an overlap with another functional gastrointestinal disorder: FD with gastroesophageal reflux (FD-GERD), epigastric pain syndrome with irritable bowel syndrome (EPS-IBS), postprandial distress syndrome with IBS (PDS-IBS), and FD-Constipation. We identified putative pathophysiology to provide a basis for treatment recommendations. A management algorithm is presented to guide primary and secondary care clinicians.

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.

Diet and intestinal bacterial overgrowth: Is there evidence?

The intestinal microbiota and its role in health and disease processes have been the subject of several studies. It is known that changes in the intestinal microbiota occur due to several factors, such as the use of medication, age, lifestyle and diseases, which can modify intestinal homeostasis and lead to excessive growth of bacteria in the small intestine, triggering a clinical condition called small bowel bacterial overgrowth (SIBO). Individuals with SIBO may present gastrointestinal symptoms ranging from nausea, diarrhea and/or constipation, and flatulence to distension and abdominal pain, resulting from poor absorption of nutrients or changes in intestinal permeability. The gold-standard treatment is based on the use of antibiotics to eradicate bacterial overgrowth. Some studies have evaluated diets in the treatment of SIBO; however, the studies are of low methodological quality, making extrapolation of the results to clinical practice unfeasible. Thus, there is still not enough scientific evidence to support a specific type of diet for the treatment of SIBO.

Hydrogen-producing small intestinal bacterial overgrowth is associated with hepatic encephalopathy and liver function

Overt hepatic encephalopathy (HE) is one of the complications of liver cirrhosis (LC), which negatively affects the prognosis and quality of life of patients. Small intestinal bacterial overgrowth (SIBO) is significantly associated with LC and its complications, including HE. We investigated the relationship between SIBO and LC, and the difference between hydrogen-producing and methane-producing SIBO (H-SIBO and M-SIBO, respectively). This is a prospective cohort study of 107 cases. Breath measurements of hydrogen and methane concentrations were performed for the diagnosis of SIBO. The study cohort included 81 males with a median age of 70 (40–86) years, and SIBO was detected in 31 cases (29.0%). There were no significant differences between the SIBO positive and SIBO negative groups. Reclassification into H-SIBO (16 cases) and others (91 cases) was performed, and the Child-Pugh score was only derived in the multivariate logistic analysis (P = 0.028, odds ratio 1.39, 95% confidence interval 1.04–1.85). Furthermore, H-SIBO was significantly associated with covert HE in chi-square test (50.0% vs. 24.2%, P = 0.034). In addition, we evaluated the therapeutic response on SIBO of rifaximin in eight covert HE patients. 20% patients with M-SIBO and 67% patients with H-SIBO showed an improvement of the breath test. In conclusion, H-SIBO, but not M-SIBO, is significantly associated with liver function, and rifaximin might be more effective for covert HE with H-SIBO. Therefore, the diagnosis of SIBO, including the classification as H-SIBO and M-SIBO, might help to determine the choice of treatment for HE.

A Single Fasting Exhaled Methane Level Correlates With Fecal Methanogen Load, Clinical Symptoms and Accurately Detects Intestinal Methanogen Overgrowth

INTRODUCTION

A 2-hour breath test is the gold standard for diagnosing intestinal methanogen overgrowth (IMO). This method can be cumbersome especially if used repetitively to monitor treatment response. Therefore, we aimed to assess the reliability of a fasting single methane measurement (SMM) in diagnosing IMO and its utility as a biomarker to monitor treatment response in subjects with IMO.

METHODS

First, we calculated the test characteristics of SMM compared with lactulose and glucose breath test in 2 large-scale retrospective cohorts. Second, the symptomology associated with SMM using various cutoffs was analyzed. Third, in a double-blind randomized control trial, the temporal stability of SMM levels in subjects taking placebo was analyzed. Fourth, stool Methanobrevibacter smithii loads were quantified using quantitative polymerase chain reaction and compared with SMM levels. Last, the change in SMM over time during antibiotic therapy was analyzed.

RESULTS

Using the cutoff of SMM ≥10 ppm, SMM had a sensitivity of 86.4% and specificity of 100% for diagnosing IMO on the glucose and lactulose breath tests and was associated with constipation (5.65 ± 3.47 vs 4.32 ± 3.62, P = 0.008). SMM remained stable for 14 weeks without treatment (P = 0.45), and antibiotics lead to a decrease in SMM after 2 days (P < 0.0001). SMM was positively associate with stool M. smithii load (R = 0.65, P < 0.0001).

DISCUSSION

Fasting SMM ≥10 ppm seems to accurately diagnose IMO, is associated with constipation, and correlates with stool M. smithii. SMM seems to be stable without treatment and decreases after antibiotics. SMM may be a useful test to diagnose IMO and monitor treatment response.

Exhaled Methane is Associated with a Lower Heart Rate

BACKGROUND

In humans, methane (CH4) is exclusively produced by the intestinal microbiota and has been implicated in several conditions including cardiovascular disease. After microbial production of CH4 in the gut, it steadily crosses into the systemic circulation and reaches the lungs where it can be detected in the exhaled breath, as a surrogate measure for intestinal CH4 production. Recent reports have shown an association between CH4 and vagal dysfunction as well as the inhibition of CH4 activity on ileal contractions with atropine, suggesting its action on the parasympathetic nervous system. Given these findings we hypothesized that CH4 may be affecting resting heart rate based on the potential effect of CH4 on the vagus nerve.

OBJECTIVES

Given its possible role in the parasympathetic nervous system, we aimed to study the relationship between breath CH4 and resting heart rate (HR) in humans. Additionally, we performed a longitudinal study analyzing the change in HR and its association to breath CH4 over time.

METHODS

First, we reviewed 1,126 subjects and compared HR in subjects with detectable and undetectable breath CH4. Second, we performed a post-hoc analysis of a randomized control trial to compare the change in HR for those who had an increase in breath CH4 vs those that had a decrease in breath CH4 over 14 weeks. Lastly, we assessed whether a larger decrease in CH4 is associated with a larger increase in HR over time.

RESULTS

In the retrospective cohort, subjects with detectable CH4 had a lower HR compared to those with undetectable CH4 (73.0±0.83 vs 76.0±0.44 beats/min; p=0.01). In the post-hoc analysis, a decrease in CH4 over time was associated with an increase in heart rate (median ∆ = 6.5 ± 8.32 beats/min, p=0.0006). Lastly, we demonstrated a biological gradient whereby a larger drop in CH4 is associated with a greater increase in heart rate (R= -0.31, p=0.03).

CONCLUSION

Our findings suggest a potential role for the microbiome (and specifically CH4 from methanogens) to regulate heart rate. Considering these findings, mechanistic studies are warranted to further investigate this potential novel microbiome-neurocardiac axis.

Progress in understanding of relationship between gut microbiota and gastrointestinal motility

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

Emerging Role of the Gut Microbiome in Irritable Bowel Syndrome

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

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.

Reference values for intake of six types of soluble and insoluble fibre in healthy UK inhabitants based on the UK Biobank data

OBJECTIVE

To obtain a set of reference values for the intake of different types of dietary fibre in a healthy UK population.

DESIGN

This descriptive cross-sectional study used the UK Biobank data to estimate the dietary patterns of healthy individuals. Data on fibre content in different foods were used to calculate the reference values which were then calibrated using real-world data on total fibre intake.

SETTING

UK Biobank is a prospective cohort study of over 500 000 individuals from across the United Kingdom with the participants aged between 40 and 69 years.

PARTICIPANTS

UK Biobank contains information on over 500 000 participants. This study was performed using the data on 19 990 individuals (6941 men, 13 049 women) who passed stringent quality control and filtering procedures and had reported above-zero intake of the analysed foods.

RESULTS

A set of reference values for the intake of six different types of soluble and insoluble fibres (cellulose, hemicelluloses, pectin and lignin), including the corresponding totals, was developed and calibrated using real-world data.

CONCLUSIONS

To our knowledge, this is the first study to establish specific reference values for the intake of different types of dietary fibre. It is well known that effects exerted by different types of fibre both directly and through modulation of microbiota are numerous. Conceivably, a deficit or excess intake of specific types of dietary fibre may detrimentally affect human health. Filling this knowledge gap opens new avenues for research in discussion in studies of nutrition and microbiota and offers valuable tools for practitioners worldwide.

Evaluation of fecal calprotectin as a marker of gastrointestinal inflammation in rosacea: A case-control study

A higher incidence of gastrointestinal diseases has been well established in patients with rosacea. However, no screening tool has been introduced for gastrointestinal disease development in rosacea. Fecal calprotectin (FC) is a calcium-binding protein, mainly derived from polymorpho-nuclear cells, such as neutrophils. It has been established as a marker of gastrointestinal inflammation. The aim of the present study was to evaluate FC levels in patients with rosacea without any gastrointestinal diseases. A prospective, case-control study was planned to investigate the relationship between rosacea and gastrointestinal involvement by evaluating FC levels and the Gastrointestinal Symptom Rating Scale (GSRS). A total of 47 patients with rosacea and 39 healthy control subjects were included in the study. The FC levels were statistically significantly higher in rosacea group than in the control group (65.96 ± 58.86 ng/mL vs 31.99 ± 20.12 ng/mL, P = .026, respectively). A statistically significant difference was also observed in GSRS values between the patient and the control groups (30.26 ± 12.48 vs 22.62 ± 7.64, P = .001, respectively). A positive correlation was noted between FC levels and the values of GSRS in the study group (r: 0.354; P = .001) and in the rosacea group (r = 0.392, P = .006). The measurement of FC may be useful in the early detection of gastrointestinal system diseases that may accompany rosacea and may provide a pathway to develop treatment strategies targeting both skin and intestinal mucosa.

Washed microbiota transplantation reduces proton pump inhibitor dependency in nonerosive reflux disease

BACKGROUND

The pathogenesis of gastroesophageal reflux disease (GERD) is closely associated with the intestinal bacteria composition and their metabolites.

AIM

To investigate whether washed microbiota transplantation (WMT) improves symptoms of nonerosive reflux disease (NERD) with proton pump inhibitor (PPI) dependency.

METHODS

Patients with recurrent NERD and PPI dependency at the First Affiliated Hospital of Guangdong Pharmaceutical University from 2017 to 2018 were included and divided into a WMT or PPI group treated with PPI with/without WMT. The endpoint was NERD symptom frequency evaluated 1 mo after WMT using reflux disease questionnaire (RDQ) and GERD questionnaire (GERDQ) scores, remission time, PPI dose, and the examination of intestinal mucosal barrier function.

RESULTS

In the WMT (n = 15) and PPI (n = 12) groups, the total remission rate at 1 mo after treatment was 93.3% vs 41.7%. Compared with the PPI group, the WMT group showed better results in GERDQ (P = 0.004) and RDQ (P = 0.003) and in remission months (8 vs 2, P = 0.002). The PPI dose was reduced to some extent for 80% of patients in the WMT group and 33.3% in the PPI group. In 24 patients, intestinal mucosal barrier function was examined before treatment, and changes in the degree of damage were observed in 13 of these patients after treatment. Only one of the 15 patients had minor side effects, including a mushy stool two or three times a day, which resolved on their own after 1 wk.

CONCLUSION

This study is the first to demonstrate that WMT may be safe and effective for relieving NERD symptoms and reducing PPI dependency and recurrence.

Hydrogen-methane breath testing results influenced by oral hygiene

The measurement of hydrogen–methane breath gases is widely used in gastroenterology to evaluate malabsorption syndromes and bacterial overgrowth. Laboratories offering breath testing provide variable guidance regarding oral hygiene practices prior to testing. Given that oral dysbiosis has the potential to cause changes in breath gases, it raises concerns that oral hygiene is not a standard inclusion in current breath testing guidelines. The aim of this study was to determine how a pre-test mouthwash may impact hydrogen–methane breath test results. Participants presenting for breath testing who had elevated baseline gases were given a chlorhexidine mouthwash. If a substantial reduction in expired hydrogen or methane occurred after the mouthwash, breath samples were collected before and after a mouthwash at all breath sample collection points for the duration of testing. Data were evaluated to determine how the mouthwash might influence test results and diagnostic status. In 388 consecutive hydrogen–methane breath tests, modifiable elevations occurred in 24.7%. Administration of a chlorhexidine mouthwash resulted in significantly (p ≤ 0.05) reduced breath hydrogen in 67% and/or methane gas in 93% of those consenting to inclusion. In some cases, this modified the diagnosis. Mean total gas concentrations pre- and post-mouthwash were 221.0 ppm and 152.1 ppm (p < 0.0001) for hydrogen, and 368.9 ppm and 249.8 ppm (p < 0.0001) for methane. Data suggest that a single mouthwash at baseline has a high probability of returning a false positive diagnosis. Variations in gas production due to oral hygiene practices has significant impacts on test interpretation and the subsequent diagnosis. The role of oral dysbiosis in causing gastrointestinal symptoms also demands exploration as it may be an underlying factor in the presenting condition that was the basis for the referral.

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

BACKGROUND

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

AIMS

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

METHODS

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

KEY RESULTS

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

CONCLUSIONS

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

The management of adult patients with severe chronic small intestinal dysmotility

Adult patients with severe chronic small intestinal dysmotility are not uncommon and can be difficult to manage. This guideline gives an outline of how to make the diagnosis. It discusses factors which contribute to or cause a picture of severe chronic intestinal dysmotility (eg, obstruction, functional gastrointestinal disorders, drugs, psychosocial issues and malnutrition). It gives management guidelines for patients with an enteric myopathy or neuropathy including the use of enteral and parenteral nutrition.

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.

Breath methane to hydrogen ratio as a surrogate marker of intestinal dysbiosis in head and neck cancer

Exhaled breath compounds can non-invasively detect head and neck squamous cell carcinoma (HNSCC). Here we investigated exhaled compounds related to intestinal bacterial carbohydrate fermentation. Fasting breath samples were collected into 3 litre FlexFoil PLUS bags from patients awaiting a biopsy procedure for suspected HNSCC. Samples were analysed using a Syft selected ion flow-tube mass spectrometer and a Quintron BreathTracker. Two tailed non-parametric significance testing was conducted with corrections for multiple imputations. 74 patients were diagnosed (histological) with HNSCC and 61 patients were benign (controls). The methane to hydrogen ratio was significantly different between cancer and non-cancer controls (p = 0.0440). This ratio increased with tumour stage with a significant difference between T1 and T4 tumours (p = 0.0259). Hydrogen levels were significantly higher in controls who were smokers (p = 0.0129), with no smoking dependent methane changes. There were no differences in short chain fatty acids between groups. Exhaled compounds of intestinal carbohydrate fermentation can detect HNSCC patients. These findings suggest a modified carbohydrate fermentation profile in HNSCC patients that is tumour stage and smoking status dependent.

Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome - An Update

Small intestinal bacterial overgrowth (SIBO) is one manifestation of gut microbiome dysbiosis and is highly prevalent in IBS (Irritable Bowel Syndrome). SIBO can be diagnosed either by a small bowel aspirate culture showing ≥10³ colony-forming units (CFU) per mL of aspirate, or a positive hydrogen lactulose or glucose breath test. Numerous pathogenic organisms have been shown to be increased in subjects with SIBO and IBS, including but not limited to Enterococcus, Escherichia coli, and Klebsiella. In addition, Methanobrevibacter smithii, the causal organism in a positive methane breath test, has been linked to constipation predominant irritable bowel syndrome (IBS-C). As M. smithii is an archaeon and can overgrow in areas outside of the small intestine, it was recently proposed that the term intestinal methanogen overgrowth (IMO) is more appropriate for the overgrowth of these organisms. Due to gut microbiome dysbiosis, patients with IBS may have increased intestinal permeability, dysmotility, chronic inflammation, autoimmunity, decreased absorption of bile salts, and even altered enteral and central neuronal activity. As a consequence, SIBO and IBS share a myriad of symptoms including abdominal pain, distention, diarrhea, and bloating. Furthermore, gut microbiome dysbiosis may be associated with select neuropsychological symptoms, although more research is needed to confirm this connection. This review will focus on the role of the gut microbiome and SIBO in IBS, as well as novel innovations that may help better characterize intestinal overgrowth and microbial dysbiosis.

Imaging Measurement of Whole Gut Transit Time in Paediatric and Adult Functional Gastrointestinal Disorders: A Systematic Review and Narrative Synthesis

BACKGROUND

functional gastrointestinal disorders (FGID) are common conditions in children and adults, often associated with abnormalities of whole gut transit. Currently, transit tests can be performed using several imaging methods, including tracking of radiopaque markers, gamma scintigraphy with the use of radioisotopes, magnetic tracking methods, tracking of movement of wireless motility capsules, and emerging magnetic resonance imaging (MRI) approaches.

OBJECTIVES

to review recent literature on diagnostic imaging techniques used to investigate whole gut transit in FGIDs.

METHODS

a systematic review was carried out. The different techniques are described briefly, with particular emphasis on contemporary literature and new developments, particularly in the field of MRI.

CONCLUSIONS

emerging MRI capsule marker methods are promising new tools to study whole gut transit in FGIDs.

Small intestinal bacterial overgrowth and chronic pancreatitis

Chronic pancreatitis (CP) is defined as a pathological fibro-inflammatory syndrome of the pancreas in individuals with genetic, environmental, and/or other risk factors who develop persistent pathological responses to parenchymal injury or stress. Because of its persistent symptoms, CP often requires lifelong treatment, which seriously affects the quality of life of patients. Small intestinal bacterial overgrowth (SIBO) is an abnormal increase in the number of bacteria and/or changes in the bacterial flora, which symptoms are similar to those of CP. In recent years, a growing number of studies have shown that SIBO may be both an important manifestation of CP and a cause of aggravating intestinal symptoms and malnutrition in patients with CP. Anti-bacterial therapy for SIBO may improve the symptoms and quality of life of patients with CP. In this paper, we discuss the relationship between SIBO and CP.

Small Intestinal Bacterial Overgrowth in Children: A State-Of-The-Art Review

Small intestinal bacterial overgrowth (SIBO) is a heterogenous and poorly understood entity characterised by an excessive growth of select microorganisms within the small intestine. This excessive bacterial biomass, in turn, disrupts host physiology in a myriad of ways, leading to gastrointestinal and non-gastrointestinal symptoms and complications. SIBO is a common cause of non-specific gastrointestinal symptoms in children, such as chronic abdominal pain, abdominal distention, diarrhoea, and flatulence, amongst others. In addition, it has recently been implicated in the pathophysiology of stunting, a disease that affects millions of children worldwide. Risk factors such as acid-suppressive therapies, alterations in gastrointestinal motility and anatomy, as well as impoverished conditions, have been shown to predispose children to SIBO. SIBO can be diagnosed via culture-dependant or culture-independent approaches. SIBO's epidemiology is limited due to the lack of uniformity and consensus of its diagnostic criteria, as well as the paucity of literature available. Antibiotics remain the first-line treatment option for SIBO, although emerging modalities such as probiotics and diet manipulation could also have a role. Herein, we present a state-of-the-art-review which aims to comprehensively outline the most current information on SIBO in children, with particular emphasis on the gut microbiota.

The Spectrum of Small Intestinal Bacterial Overgrowth (SIBO)

PURPOSE OF REVIEW

To critically review recent (past 3 years) literature on the definition, diagnosis, and management of small intestinal bacterial overgrowth (SIBO).

RECENT FINDINGS

While various series continue to illustrate the occurrence of SIBO in disease states where well-known risk factors for its occurrence are present (hypochlorhydria, disorders of intestinal structure or motor function, pancreatic insufficiency, and chronic liver disease, for example), the current challenge is in defining the limits of SIBO. Is SIBO truly common among those with "functional" gastrointestinal symptoms where there is no evidence of maldigestion or malabsorption; the original hallmarks of SIBO? Our attempts to address this question continue to be hampered by the limitations of our diagnostic tool kit. There is hope-the application of modern molecular techniques to the study of the small intestinal microbiome, together with some innovative sampling techniques, such as real-time intestinal gas sampling, may soon allow us to truly define the spectrum of SIBO. SIBO, once removed from its original confines as a cause of malabsorption syndrome, has proven to be an elusive and moving target. Only the most rigorous studies employing validated methodologies will finally corral this mysterious entity.

Hydrogen- and Methane-Based Breath Testing and Outcomes in Patients With Heart Failure

BACKGROUND

Recent evidence endorses gut microbiota dysregulation in the pathophysiology of heart failure (HF). Small intestinal bacterial overgrowth (SIBO) might be present in HF and associated with poor clinical outcomes. Lactulose breath testing is a simple noninvasive test that has been advocated as a reliable indicator of SIBO. In patients with HF, we aimed to evaluate the association with clinical outcomes of the exhaled hydrogen (H₂) and methane (CH₄) concentrations through the lactulose breath test.

METHODS AND RESULTS

We included 102 patients with HF in which lactulose SIBO breath tests were assessed. Cumulative gas was quantified by the area under the receiver operating characteristic curve of CH₄ (AUC-CH₄) and H₂ (AUC-H₂). Clinical end points included the composite of all-cause death with either all-cause or HF hospitalizations, recurrent all-cause hospitalizations, and recurrent HF hospitalizations. Medians (interquartile ranges) of AUC-H₂ and AUC-CH₄ were 1290 U (520-2430) and 985 U (450-2120), respectively. In multivariable analysis, AUC-H₂ (per 1000 U) was associated with all-cause death/all-cause hospitalization (hazard ratio [HR] 1.21, 95% CI 1.04-1.40; P = .012), all-cause death/HF hospitalization (HR 1.20, 95% CI 1.03-1.40; P = .021), and an increase in the rate of recurrent all-cause (incidence rate ratio [IRR] 1.31, 95% CI 1.14-1.51; P < .001) and HF (IRR 1.41, 95% CI 1.15-1.72; P = .001) hospitalizations. AUC-CH₄ was not associated with any of these end points.

CONCLUSIONS

AUC-H₂, a safe and noninvasive method for SIBO estimation, is associated with higher risk of long-term adverse clinical events in patients with HF. In contrast, AUC-CH₄ did not show any prognostic value.