Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowel syndrome

The Role of Bacteria-Derived Hydrogen Sulfide in Multiple Axes of Disease

In this review article, we discuss and explore the role of bacteria-derived hydrogen sulfide. Hydrogen sulfide is a signaling molecule produced endogenously that plays an important role in health and disease. It is also produced by the gut microbiome. In the setting of microbial disturbances leading to disruption of intestinal homeostasis (dysbiosis), the concentration of available hydrogen sulfide can also vary leading to pathologic sequelae. The brain-gut axis is the original studied paradigm of gut microbiome and host interaction. In recent years, our understanding of microbial and host interaction has expanded greatly to include specific pathways that have branched into their own axes. These axes share a principal concept of microbiota changes, intestinal permeability, and an inflammatory response, some of which are modulated by hydrogen sulfide (H2S). In this review, we will discuss multiple axes including the gut-immune, gut-heart, and gut-endocrine axes. We will evaluate the role of H2S in modulation of intestinal barrier, mucosal healing in intestinal inflammation and tumor genesis. We will also explore the role of H2S in alpha-synuclein aggregation and ischemic injury. Finally, we will discuss H2S in the setting of metabolic syndrome as int pertains to hypertension, atherosclerosis and glucose-like peptide-1 activity. Majority of studies that evaluate hydrogen sulfide focus on endogenous production; the role of this review is to examine the lesser-known bacteria-derived source of hydrogen sulfide in the progression of diseases as it relates to these axes.

The Relationship Between Irritable Bowel Syndrome and Metabolic Syndrome: A Systematic Review and Meta-Analysis of 49,662 Individuals

BACKGROUND

Studies have shown mixed results regarding the association between irritable bowel syndrome (IBS) and metabolic syndrome (MS); This study aimed to assess the susceptibility of IBS patients to MS and its individual components.

METHODS

PubMed, Scopus, Embase, and Web of Science were searched on 1/1/2023. Eligible studies were screened, and data on study characteristics, IBS diagnostic criteria, and metabolic syndrome components were extracted. Data were analysed in RevMan 5.4, with results reported as relative risk (RR) or mean difference (MD) and 95% confidence intervals. Statistical significance was set at p < 0.05.

RESULTS

IBS was associated with an increased risk of MS (RR = 2.05, 95% CI = 1.50-2.79, p < 0.00001), with a higher risk among IBS-D patients (RR = 3.09, 95% CI = 2.41-3.97, p < 0.00001). IBS patients showed increased HOMA-IR (MD = 0.21, 95% CI = 0.15-0.26, p < 0.00001), higher obesity risk (RR = 1.46, 95% CI = 1.10-1.93, p = 0.009), elevated BMI (MD = 1.51, 95% CI = 0.98-2.03, p-value < 0.00001), waist circumference (MD = 5.01, 95% CI = 1.29-8.72, p = 0.008), and an association with systolic hypertension (MD = -0.50, 95% CI = -0.60 to -0.40, p-value < 0.00001). IBS was also linked to higher LDL (MD = 5.98, 95% CI = 0.91-11.05, p = 0.02), total cholesterol (MD = 12.21, 95% CI = 6.23-18.18, p < 0.0001), and triglycerides (MD = 11.93, 95% CI = 11.55-12.31, p < 0.00001).

CONCLUSIONS

This analysis indicates a potential association between IBS and metabolic syndrome, including its components such as obesity, hypertension, and lipid profile abnormalities. However, significant heterogeneity among studies limits the generalisability of these findings. Clinicians should remain aware of the possible link and consider individualised preventive and management strategies.

The role of the gut microbiome in disorders of gut-brain interaction

Disorders of Gut-Brain Interaction (DGBI) are widely prevalent and commonly encountered in gastroenterology practice. While several peripheral and central mechanisms have been implicated in the pathogenesis of DGBI, a recent body of work suggests an important role for the gut microbiome. In this review, we highlight how gut microbiota and their metabolites affect physiologic changes underlying symptoms in DGBI, with a particular focus on their mechanistic influence on GI transit, visceral sensitivity, intestinal barrier function and secretion, and CNS processing. This review emphasizes the complexity of local and distant effects of microbial metabolites on physiological function, influenced by factors such as metabolite concentration, duration of metabolite exposure, receptor location, host genetics, and underlying disease state. Large-scale in vitro work has elucidated interactions between host receptors and the microbial metabolome but there is a need for future research to integrate such preclinical findings with clinical studies. The development of novel, targeted therapeutic strategies for DGBI hinges on a deeper understanding of these metabolite-host interactions, offering exciting possibilities for the future of treatment of DGBI.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Rifaximin-Alpha Increases Lactase Activity in Patients with Irritable Bowel Syndrome Without Constipation and Small Intestinal Bacterial Overgrowth

BACKGROUND

Irritable bowel syndrome symptoms are associated with diverse pathophysiological mechanisms including small intestinal bacterial overgrowth and food intolerance. Small intestinal bacterial overgrowth leads to the decreased activity of several digestive enzymes, including lactase.

AIMS

To assess the efficacy of rifaximin-alpha on the symptoms and lactase activity of patients with irritable bowel syndrome without constipation.

METHODS

This was a prospective, pilot study. The recruited patients had irritable bowel syndrome without constipation (Rome IV criteria), a positive lactulose-Hydrogen Breath Test for small intestinal bacterial overgrowth, low urinary D-Xylose levels measured using the Lactest® test, and self-reported lactose intolerance. In addition, lactose HBT was performed. All patients received 400 mg rifaximin-alpha every 8 h for 2 weeks. Four weeks after the intervention, lactose and lactulose HBT were performed, and the symptoms and urinary D-Xylose levels were evaluated.

RESULTS

After treatment with rifaximin-alpha, 60% of the patients reported improvement in abdominal pain, 44% in bloating, 36% in flatulence, 60% in borborygmi, and 72% in stool consistency. A negative lactulose-Hydrogen Breath Test result for SIBO was documented in 32% of patients, and lactose maldigestion by lactose-Hydrogen Breath Test was reduced from 88 to 52% of the studied subjects. The median D-Xylose levels before and after treatment were 7.6 (IQR 4.34-13.7) mg/dL vs. 10.4 (IQR 7.1-17.3) mg/dL, p = 0.002.

CONCLUSIONS

Rifaximin-alpha caused symptomatic improvement, reduced lactose maldigestion, and reduced positive Hydrogen Breath Test results for small intestinal bacterial overgrowth in patients with irritable bowel syndrome without constipation.

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

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

Effect of Iberogast (STW5) on tolerance to colonic gas in patients with irritable bowel syndrome: A randomized, double-blind, placebo control clinical trial

BACKGROUND

STW5 is an herbal medicinal product that, in previous studies, reduced abdominal pain in irritable bowel syndrome (IBS). The effect of STW5 on gas-related abdominal symptoms is unknown.

AIM

To determine the effects of STW5, compared to placebo, on the responses to colonic gas in IBS.

METHODS

Using a cross-over design, two gas challenge tests were performed in 10 patients with IBS and bloating after 2-weeks treatment with (a) STW5 and (b) placebo. The challenge test consisted in continuous infusion of gas into the colon (24 mL/min for 60 min), followed by a 30-min free evacuation period. Gas evacuation, symptom perception, and abdominal distension were continuously registered.

RESULTS

Colonic gas filling was associated to a significant rise in abdominal symptom perception, that was significantly greater when patients were on-placebo (score increment 4.0 ± 0.3) compared with on-STW5 (score increment 3.2 ± 0.4; p = 0.035). Gas filling was associated to a progressive abdominal distension that was similar with both treatments. Opening of the rectal cannula produced a massive gas evacuation, similar after both treatments, associated to a return of abdominal perception and distension to basal levels when patients were on-STW5 (score increment -0.1 ± 0.4; distension 0.3 ± 0.2 cm; p = 0.399, and p = 0.112 vs. basal), whereas both remained increased on-placebo (score increment 0.5 ± 0.3; distension 0.8 ± 0.3 cm; p = 0.048, and p = 0.016 vs. infusion start).

CONCLUSIONS

STW5 improves colonic gas tolerance in IBS patients with bloating without a significant effect on gas retention and evacuation. This medicinal product can be beneficious for treatment of gas-related abdominal symptoms in patients with bloating. EudraCT: 2019-003976-38.

Long-Term Oral Administration of Hyperimmune Egg-Based IgY-Rich Formulations Induces Mucosal Immune Response and Systemic Increases of Cytokines Involved in Th2- and Th17-Type Immune Responses in C57BL/6 Mice

Three hyperimmune egg-based formulations rich in immunoglobulin Y (IgY) were orally administered (daily, for up to 90 days) to C57BL/6 mice that were not microbially challenged. The serum levels of 32 cytokines were quantified every 30 days. Histopathology, hematology, and serum biochemistry investigations were also performed. As a sign of increased immune activity, lymphohistiocytic infiltrates were detected in the digestive tract and the liver after 30, 60, and 90 days of treatment. These infiltrates were also present in the lungs after 30 and 60 days, but not at 90 days. Blood analysis indicated systemic inflammation after 30 days of treatment: increases in pro-inflammatory cytokines, glycemia, total serum proteins, ALT, and ALP. After 60 and 90 days of treatment, the analyzed blood parameters showed mixed signs of both increased and decreased inflammation. The increased cytokines, which varied with formulation and time of exposure, indicated a combination of mostly Th17- and Th2-type immune responses. As the mice were healthy and housed in standardized sanitary conditions, and were not microbially challenged, the data were consistent with an interaction of IgY with the gut-associated lymphoid tissue as the main mechanism of action. This interaction generated a local immune response, which subsequently induced a systemic response.

Critical appraisal of the SIBO hypothesis and breath testing: A clinical practice update endorsed by the European society of neurogastroenterology and motility (ESNM) and the American neurogastroenterology and motility society (ANMS)

BACKGROUND

There is compelling evidence that microbe-host interactions in the intestinal tract underlie many human disorders, including disorders of gut-brain interactions (previously termed functional bowel disorders), such as irritable bowel syndrome (IBS). Small intestinal bacterial overgrowth (SIBO) has been recognized for over a century in patients with predisposing conditions causing intestinal stasis, such as surgical alteration of the small bowel or chronic diseases, including scleroderma and is associated with diarrhea and signs of malabsorption. Over 20 years ago, it was hypothesized that increased numbers of small intestine bacteria might also account for symptoms in the absence of malabsorption in IBS and related disorders. This SIBO-IBS hypothesis stimulated significant research and helped focus the profession's attention on the importance of microbe-host interactions as a potential pathophysiological mechanism in IBS.

PURPOSE

However, after two decades, this hypothesis remains unproven. Moreover, it has led to serious unintended consequences, namely the widespread use of unreliable and unvalidated breath tests as a diagnostic test for SIBO and a resultant injudicious use of antibiotics. In this review, we examine why the SIBO hypothesis remains unproven and, given the unintended consequences, discuss why it is time to reject this hypothesis and its reliance on breath testing. We also examine recent IBS studies of bacterial communities in the GI tract, their composition and functions, and their interactions with the host. While these studies provide important insights to guide future research, they highlight the need for further mechanistic studies of microbe-host interactions in IBS patients before we can understand their possible role in diagnosis and treatment of patient with IBS and related disorders.

In Vitro Models for Investigating Intestinal Host-Pathogen Interactions

Infectious diseases are increasingly recognized as a major threat worldwide due to the rise of antimicrobial resistance and the emergence of novel pathogens. In vitro models that can adequately mimic in vivo gastrointestinal physiology are in high demand to elucidate mechanisms behind pathogen infectivity, and to aid the design of effective preventive and therapeutic interventions. There exists a trade-off between simple and high throughput models and those that are more complex and physiologically relevant. The complexity of the model used shall be guided by the biological question to be addressed. This review provides an overview of the structure and function of the intestine and the models that are developed to emulate this. Conventional models are discussed in addition to emerging models which employ engineering principles to equip them with necessary advanced monitoring capabilities for intestinal host-pathogen interrogation. Limitations of current models and future perspectives on the field are presented.

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

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

The Next Generation Fecal Microbiota Transplantation: To Transplant Bacteria or Virome

Fecal microbiota transplantation (FMT) has emerged as a promising therapeutic approach for dysbiosis-related diseases. However, the clinical practice of crude fecal transplants presents limitations in terms of acceptability and reproductivity. Consequently, two alternative solutions to FMT are developed: transplanting bacteria communities or virome. Advanced methods for transplanting bacteria mainly include washed microbiota transplantation and bacteria spores treatment. Transplanting the virome is also explored, with the development of fecal virome transplantation, which involves filtering the virome from feces. These approaches provide more palatable options for patients and healthcare providers while minimizing research heterogeneity. In general, the evolution of the next generation of FMT in global trends is fecal microbiota components transplantation which mainly focuses on transplanting bacteria or virome.

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.

A systematic review and meta-analysis of the correlation between polycystic ovary syndrome and irritable bowel syndrome

BACKGROUND

Research on the prevalence of irritable bowel syndrome (IBS) among polycystic ovary syndrome (PCOS) patients has gained significant momentum over the years. However, it remains unclear whether PCOS is related to a higher prevalence of IBS. The objective of this systematic review and meta-analysis was to fully study IBS correlation with PCOS.

METHODS

From inception until October 16th, 2022, all observational studies documenting IBS prevalence in PCOS patients were collected from the China national knowledge infrastructure(CNKI), China Science and Technology Journal Database(VIP), Wanfang database, PubMed, Embase, Web of Science, and Cochrane databases. The quality of case-control studies was assessed with Newcastle-Ottawa Scale. Review Manager 5.3 was used to determine the pooled odds ratio (OR) and 95% confidence interval (CI).

RESULTS

5 case-control studies involving 1268 individuals and one cross-sectional study involving 291 participants were included in our qualitative analysis. The quantitative analysis was conducted based on five case-control studies. Four case-control studies involving 1063 participants showed a higher prevalence of IBS in PCOS This meta-analysis revealed an almost twice higher risk of IBS in comparison with controls (OR = 2.23, 95%CI:1.58-3.14, p < 0.001; I²=41%, p = 0.150). Four sensitivity analyses validated the consistency of the aggregated findings.

CONCLUSION

This meta-analysis and systematic review demonstrated a significant association between PCOS and increased odds of IBS. However, more high-quality and well-controlled research is essential to increase the robustness of our conclusions.

Loose ends in the differential diagnosis of IBS-like symptoms

Two thirds of the patients we believed to have IBS in the 1970's have since been possible to diagnose with treatable conditions like bile acid diarrhea, inflammatory bowel disease, microscopic colitis, celiac disease, disaccharide malabsorption, exocrine pancreatic insufficiency, or rare genetic variants. Despite advances in diagnostic techniques a substantial proportion of patients continue suffering from IBS-like symptoms that cannot be explained by current knowledge. Although it is likely that further research will reveal small but important subgroups of patients with treatable mechanisms for IBS-like symptoms, we propose that only two large groups remain for being addressed in the clinic: those with connective tissue disorders such as Ehlers-Danlos syndrome or hypermobility spectrum disorders and those with autism spectrum disorders. Patients with connective tissue disorders exhibit identifiable disturbances of gut motor function and possibly increased gut permeability as underlying mechanisms for IBS-like symptoms. Autism spectrum disorders pose a much more difficult problem in the clinic. Disturbances of perception combined with anxiety and excessive worry about signals from the gut can lead to an endless but futile search for something being wrong. The search can involve large numbers of care givers, no one understanding the patient's suffering. Others may try to change their diet to lessen symptoms, only to find that almost all foods may cause worrying perceptions from the gut. Early recognition of autism spectrum disorders is essential for finding better ways to help patients with gastrointestinal and, as is often the case, extraintestinal symptoms.

Antibiotics and Probiotics for Irritable Bowel Syndrome

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

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

Background and Aim

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

Method

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

Results

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

Conclusion

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

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.

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

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

Methanogens and Hydrogen Sulfide Producing Bacteria Guide Distinct Gut Microbe Profiles and Irritable Bowel Syndrome Subtypes

INTRODUCTION

Irritable bowel syndrome (IBS) includes diarrhea-predominant (IBS-D) and constipation-predominant (IBS-C) subtypes. We combined breath testing and stool microbiome sequencing to identify potential microbial drivers of IBS subtypes.

METHODS

IBS-C and IBS-D subjects from 2 randomized controlled trials (NCT03763175 and NCT04557215) were included. Baseline breath carbon dioxide, hydrogen (H 2 ), methane (CH 4 ), and hydrogen sulfide (H 2 S) levels were measured by gas chromatography, and baseline stool microbiome composition was analyzed by 16S rRNA sequencing. Microbial metabolic pathways were analyzed using Kyoto Encyclopedia of Genes and Genomes collection databases.

RESULTS

IBS-C subjects had higher breath CH 4 that correlated with higher gut microbial diversity and higher relative abundance (RA) of stool methanogens, predominantly Methanobrevibacter , as well as higher absolute abundance of Methanobrevibacter smithii in stool. IBS-D subjects had higher breath H 2 that correlated with lower microbial diversity and higher breath H 2 S that correlated with higher RA of H 2 S-producing bacteria, including Fusobacterium and Desulfovibrio spp. The predominant H 2 producers were different in these distinct microtypes, with higher RA of Ruminococcaceae and Christensenellaceae in IBS-C/CH 4 + (which correlated with Methanobacteriaceae RA) and higher Enterobacteriaceae RA in IBS-D. Finally, microbial metabolic pathway analysis revealed enrichment of Kyoto Encyclopedia of Genes and Genomes modules associated with methanogenesis and biosynthesis of methanogenesis cofactor F420 in IBS-C/CH 4 + subjects, whereas modules associated with H 2 S production, including sulfate reduction pathways, were enriched in IBS-D.

DISCUSSION

Our findings identify distinct gut microtypes linked to breath gas patterns in IBS-C and IBS-D subjects, driven by methanogens such as M. smithii and H 2 S producers such as Fusobacterium and Desulfovibrio spp, respectively.

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

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

Relationship between untreated obstructive sleep apnea and breath hydrogen and methane after glucose load

BACKGROUND

Patients with sleep disturbances have gastrointestinal symptoms. Breath hydrogen (H₂) and methane (CH₄) indicating small intestinal bacterial overgrowth (SIBO) might be related with these symptoms. The study was conducted to assess the link between breath profiles and untreated obstructive sleep apnea (OSA).

METHODS

: This prospective study enrolled consecutive patients with OSA using polysomnography. Heart rate variability (HRV) was used as a measurement for the balance of autonomic nervous system during polysomnography. Glucose breath test (GBT) to evaluate breath H₂ and CH₄ and bowel symptom questionnaire to investigate associated intestinal symptoms were performed.

RESULTS

Among 52 patients with OSA, 16 (30.8%) showed positivity to GBT. Although no significant difference was shown in GBT positivity between patients with healthy controls and patients with OSA (13.3% vs 30.8%, P = 0.109), breath H₂ and CH₄ levels in the OSA group were significantly higher than those in controls (P < 0.05). Flatulence was significantly common in OSA groups with GBT positivity than those without GBT positivity. Multivariate analysis demonstrated that waist-to-hip ratio (odds ratio = 12.889; 95% confidence interval (CI): 1.257-132.200; P = 0.031) and low-to-high-frequency ratio of HRV (odds ratio = 1.476; 95% CI: 1.013-2.151, P = 0.042) are independently related to GBT positivity in patients with OSA.

CONCLUSION

: Elevated breath H₂ or CH₄ after glucose load might not be an uncommon finding in patients with untreated OSA. Abdominal obesity and autonomic imbalance dysfunction are significantly associated with GBT positivity in OSA patients. SIBO could be considered as target for therapeutic management in OSA patients.

A systematic review and meta-analysis on the prevalence of non-malignant, organic gastrointestinal disorders misdiagnosed as irritable bowel syndrome

Treatable gastrointestinal disorders in patients with symptoms typical for irritable bowel syndrome (IBS) may be overlooked. The prevalence of five gastrointestinal conditions-bile acid diarrhoea (BAD), carbohydrate malabsorption (CM), microscopic colitis (MC), pancreatic exocrine insufficiency (PEI) and small intestinal bacterial overgrowth (SIBO) was systematically assessed from studies including consecutive patients meeting diagnostic criteria for IBS. 4 databases were searched from 1978 to 2020. Studies were included if they evaluated the prevalence of these conditions in secondary healthcare setting. Estimated pooled rates were calculated and statistical heterogeneity between studies was evaluated using Q and I2 statistics. Seven studies (n = 597) estimated the pooled prevalence for BAD as 41% (95% CI 29-54). 17 studies (n = 5068) estimated that of MC as 3% (95% CI 2-4%). Two studies (n = 478) suggested a rate of 4.6% (range: 1.8-6.1%) for PEI. Using breath testing, 26 studies (n = 6700) and 13 studies (n = 3415) estimated the prevalence of lactose and fructose malabsorption as 54% (95% CI 44-64%) and 43% (95% CI 23-62%); 36 studies (n = 4630) and 22 studies (n = 2149) estimated that of SIBO as 49% (95% CI 40-57%) with lactulose and 19% (95% CI 13-27%) with glucose. Rates of all conditions were significantly higher than in healthy controls. A significant proportion of patients presenting to secondary care with IBS have an organic condition which may account for their symptoms. Failure to exclude such conditions will deny patients effective treatment.

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.

Review article: Diagnosis and investigation of irritable bowel syndrome

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

Evaluation of bowel habits in patients with acne vulgaris

PURPOSE

To evaluate the bowel habits of patients with acne vulgaris.

METHOD

In this case-control study, socio-demographical characteristics of the participants (age, gender, marital status, educational status, profession, economic status, smoking-alcohol habits, chronic diseases, previous operations, people they live with and diet) were questioned and the global acne grading scores of the patients were calculated. Bristol Stool Scale, Rome III IBS Criteria, International Physical Activity Questionnaire-Short Form, Hospital Anxiety Depression and KADF (dietary fibre information) scales were completed.

RESULTS

The patient group consisted of 102 participants and the control group consisted of 104 participants. The mean age was 20.9 ± 3.9 years old in the case group and 21.8 ± 5.0 years old in the control group. Patient and control groups were similar in terms of age and gender. Smoking rates were significantly higher in the patient group (P = .035). The amount of coffee consumed/day was significantly higher in the patient group (P = .040). According to the global acne grading scores, 55.9% (n = 57) had medium, 39.2% (n = 40) had mild, 3.9% (n = 4) had severe and 1% (n = 1) had very severe acne. Anxiety scores were found to be significantly higher in the patient group (P = .005). When the case and control groups were compared for IBS presence, no significant difference was found (P = .317). Also, IBS was not related to acne severity (P = .162).

CONCLUSION

Further large sample sized studies are needed on this subject, as there is strong evidence about brain-gut-skin axis existence.

Microbiota and the irritable bowel syndrome

Gut microbiota plays a vital role in human health. The number of microorganisms inhabiting the gastrointestinal (GI) tract has been estimated to exceed 1013. The dominant genera in the human intestine are Firmicutes (more than 180 species of Lactobacillus), Actinobacteria (among others the Bifidobacteriae), Bacteroidetes (the most important is B. fragilis) and Proteobacteria (E. coli, Salmonella, Yersinia, Shigella, Vibrio, Haemophilus, etc.), but the composition of the flora varies individually, as well as in relation to factors such as host genetics, stress, diet, antibiotics and early childhood experiences. Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders (FGIDs), which has now been renamed disorders of gut-brain interaction, which affect a large number of people worldwide. It is characterized by abdominal pain and altered bowel habits in the absence of obvious anatomic or physiologic abnormalities. It poses a negative economic impact to the global health care system in addition to reducing the quality of life in patients. The pathophysiology of IBS is not fully understood. In IBS subjects gut microbiota relative to healthy controls was observed with an increase in Enterobacteriaceae, Ruminococcus, Clostridium, Dorea species and a decrease of Lactobacillus, Bifidobacterium, and Faecalibacterium species. IBS with diarrhea predominance (IBS-D) IBS with mixed bowel habits (IBS-M) share similarities in the microbial profile. Recent studies suggest that perturbations within "brain-gut-microbiota" axis may lead to IBS development. The aim of this review was to highlight the potential role of gut microbiota on pathophysiological mechanisms underlying IBS.

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

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

A Comprehensive Review of Transaminitis and Irritable Bowel Syndrome

We observed in the literature that irritable bowel syndrome (IBS) may be linked to irregular parameters of the metabolic system (MS) and liver function. For that reason, we conducted this systematic review to comprehensively analyze the association of transaminitis (elevated alanine transaminase (ALT)) with IBS. This review was designed by following methods described in the Cochrane Handbook for Systematic Reviews of Interventions. Published peer-reviewed journal articles were included. Data were extracted based on study design, age, gender, author, date of publication or availability online, publication type, participants, gender (M/F), and types of IBS. Our electronic multiple databases yielded a total of 519 preliminary studies; we then removed duplicate studies and left with 326 studies. After reviewing the full text of these articles, a total of 83 studies were eliminated and lastly, three studies were selected for this systematic review for quantitative and qualitative analysis. All the enrolled subjects in included studies were diagnosed with IBS by the Rome II and III criteria and among these sub-jects, 50.4% had IBS-D, 13.8% had IBS-C, 30.3% had IBS-M, and 3.5% had IBS-U. The prevalence of elevated ALT with other liver enzymes (γ-GT levels and aspartate aminotransferase (AST)) in patients with irritable bowel syndrome whether their body mass index (BMI) was high or not (16.9% vs. 7.7%; p=0.015) and γ-GT (24.1% vs. 11.5%; p=0.037), Lee et al., 2016. The IBS-D subtype was seen more commonly in patients whose alcohol intake was significantly high however their study data showed no significant change in elevation of ALT. The upper limits normal values for serum liver enzymes were de-fined as 41 international per liter in males and 31 international units per liter in females for ALT. No significant relationships were observed between IBS status and elevated γ-GT (OR, 1.647; 95% CI, 0.784-3.461). The review study proposes a potential relation between elevated ALT levels, MS, and IBS, and this review might be the first review in IBS patients to observe the association of elevated ALT in the IBS population. Although further additional trials with a large sample size will be required to confirm these results. Furthermore, for assessing the efficacy of the manipulation of gut microbiota ran-domized controlled trials in a large population of IBS patients are needed to establish a causal-resultant relationship between IBS, MS, and liver damage.

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.

Mechanisms Underlying the Biological Effects of Molecular Hydrogen

Aberrant redox-sensitive reactions and accumulation of oxidative damage can impair body functions and contribute to the development of various pathologies and aging. Although antioxidant substances have long been recognized as a measure of alleviating oxidative stress and restoring redox balance, the arsenal of effective means of preventing the development of various disorders, is still limited. There is an emerging field that utilizes molecular hydrogen (H₂) as a scavenger of free radicals and reactive oxygen species (ROS). Among the remarkable characteristics of H₂ is its ability to counteract the harmful effects of hydroxyl radical and peroxynitrite without affecting the activity of functionally important ROS, such as hydrogen peroxide and nitric oxide. The beneficial effects of H₂ have been documented in numerous clinical studies and studies on animal models and cell cultures. However, the established scavenging activity of H₂ can only partially explain its beneficial effects because the effects are achieved at very low concentrations of H₂. Given the rate of H₂ diffusion, such low concentrations may not be sufficient to scavenge continuously generated ROS. H₂ can also act as a signaling molecule and induce defense responses. However, the exact targets and mechanism(s) by which H₂ exerts these effects are unknown. Here, we analyzed both positive and negative effects of the endogenous H₂, identified the redox-sensitive components of the pathways affected by molecular hydrogen, and also discussed the potential role of molecular hydrogen in regulating cellular redox.

Early hydrogen excretion peaks during breath tests. Small intestinal bacterial overgrowth or accelerated transit?

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) has been reported with varying prevalence, depending upon the criteria used for diagnosis. Lactulose and glucose breath tests are the most used in clinical settings. Early rises of hydrogen excretion during a lactose breath test suggest SIBO, but the finding could result from accelerated mouth-to-caecum transit time.

AIMS

Defining the prevalence of early hydrogen peaks during lactose breath tests and assessing the proportion of patients affected by SIBO.

METHODS

An early (≤ 60') hydrogen excretion peak was observed in 120/663 patients with positive lactose hydrogen breath test. Eighty-one of them underwent a 50 g-9sample-glucose hydrogen breath test to diagnose SIBO.

RESULTS

The glucose breath test proved positive in 11/81 (13.6%) patients. The positivity rate was 18.2% (2/11) in those with the first peak detected at 30' and 12.8% (9/70) in those with the peak occurring at 60'.

CONCLUSIONS

Early hydrogen excretion peaks are rarely associated with SIBO. The low positive predictive value indicates that the finding does not help identifying patients at high risk for this condition. Indirectly, the present data support the opinion that the prevalence of SIBO diagnosed by standard lactulose breath tests is much lower than reported, and the reliability of the test is low.

Effects of Bovine Colostrum with or without Egg on In Vitro Bacterial-Induced Intestinal Damage with Relevance for SIBO and Infectious Diarrhea

Small intestinal bacterial overgrowth (SIBO) occurs commonly, is difficult to treat, and frequently recurs. Bovine colostrum (BC) and chicken eggs contain immunoglobulins and other components that possess antimicrobial, immunoregulatory, and growth factor activities; however, it is not known if they have the ability to reduce injury caused by the presence of bacteria associated with SIBO (Streptococcus, Escherichia coli, Staphylococcus, Bacteroides, Klebsiella, Enterococcus, and Proteus) and infectious diarrhea (enteropathogenic Escherichia coli, Salmonella). We examined the effects of BC, egg, or the combination, on bacterial growth and bacteria-induced changes in transepithelial electrical resistance (TEER) and bacterial translocation across confluent Caco-2 monolayers. BC, egg, or the combination did not affect bacterial growth. Adding bacteria to monolayers reduced TEER and (with minor variations among species) increased bacterial translocation, increased monolayer apoptosis (increased caspase-3 and Baxα, reduced Bcl2), increased intercellular adhesion molecule 1 (ICAM-1), and reduced cell adhesion molecules zonulin1 (ZO1) and claudin-1. BC, egg, or the combination reduced these effects (all p < 0.01) and caused additional increases in vascular endothelial growth factor (VEGF) and Heat Shock Protein 70 (Hsp70) expression. We conclude that BC ± egg strengthens mucosal integrity against a battery of bacteria relevant for SIBO and for infectious diarrhea. Oral BC ± egg may have clinical value for these conditions, especially SIBO where eradication of precipitating organisms may be difficult to achieve.

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

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

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

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

Induced volatolomics of pathologies

Volatolomics allows us to elucidate cell metabolic processes in real time. In particular, a volatile organic compound (VOC) excreted from our bodies may be specific for a certain disease, such that measuring this VOC may afford a simple, fast, accessible and safe diagnostic approach. Yet, finding the optimal endogenous volatile marker specific to a pathology is non-trivial because of interlaboratory disparities in sample preparation and analysis, as well as high interindividual variability. These limit the sensitivity and specificity of volatolomics and its applications in biological and clinical fields but have motivated the development of induced volatolomics. This approach aims to overcome issues by measuring VOCs that result not from an endogenous metabolite but, rather, from the pathogen-specific or metabolic-specific enzymatic metabolism of an exogenous biological or chemical probe. In this Review, we introduce volatile-compound-based probes and discuss how they can be exploited to detect and discriminate pathogenic infections, to assess organ function and to diagnose and monitor cancers in real time. We focus on cases in which labelled probes have informed us about metabolic processes and consider the potential and drawbacks of the probes for clinical trials. Beyond diagnostics, VOC-based probes may also be effective tools to explore biological processes more generally.

Irritable bowel syndrome

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

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.

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

Background/Aims

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

Methods

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

Results

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

Conclusions

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

Small Intestinal Bacterial Overgrowth: Clinical Features and Therapeutic Management

Small intestinal bacterial overgrowth (SIBO) is a common, yet underrecognized, problem. Its prevalence is unknown because SIBO requires diagnostic testing. Although abdominal bloating, gas, distension, and diarrhea are common symptoms, they do not predict positive diagnosis. Predisposing factors include proton-pump inhibitors, opioids, gastric bypass, colectomy, and dysmotility. Small bowel aspirate/culture with growth of 10-10 cfu/mL is generally accepted as the "best diagnostic method," but it is invasive. Glucose or lactulose breath testing is noninvasive but an indirect method that requires further standardization and validation for SIBO. Treatment, usually with antibiotics, aims to provide symptom relief through eradication of bacteria in the small intestine. Limited numbers of controlled studies have shown systemic antibiotics (norfloxacin and metronidazole) to be efficacious. However, 15 studies have shown rifaximin, a nonsystemic antibiotic, to be effective against SIBO and well tolerated. Through improved awareness and scientific rigor, the SIBO landscape is poised for transformation.

Gastrointestinal consequences of cancer treatment: evaluation of 10 years' experience at a tertiary UK centre

OBJECTIVE

Up to 90% of patients treated for pelvic cancers experience chronic gastrointestinal (GI) symptoms. This study characterises this patient cohort at a single centre, addressing a paucity of publications reporting 'real-world' experiences.

METHOD

Outpatient referrals, from oncology to the gastroenterology and nutrition services, at a tertiary London hospital from 2006 to 2016, were retrospectively identified. Patient characteristics, reported symptoms, investigations, diagnoses, response to therapeutics and follow-up were recorded.

RESULTS

Of 269 patients referred, 81% were within the latter 5 years. A total of 260 patients had diagnoses of pelvic cancers (prostatic (52%), cervical (19%) and endometrial (19%)). Among 247 treated with radiotherapy, the median time from radiotherapy to symptom onset was 8 months. Common symptoms were rectal bleeding (51%), diarrhoea (32%), faecal urgency (19%) and pain (19%). Patients underwent a median of three investigations including lower GI endoscopy (86%), thyroid function tests (33%) and glucose hydrogen breath test (30%). Diagnoses included radiation proctopathy (39%), colonic polyps (16%), pelvic floor dysfunction (12%), bile acid malabsorption (BAM) (8%), small intestinal bacterial overgrowth (SIBO) (8%), vitamin D deficiency (7%) and iron deficiency (7%). Among 164 discharged patients, the time to discharge was 7 months, after a median of two appointments.

CONCLUSIONS

This unique patient group reports a complex mix of symptoms and requires specialist review and consideration of often uninvestigated diagnoses (pelvic dysfunction, BAM, SIBO and nutritional deficiencies). Such patients are often overlooked, compared with those suffering many other chronic GI disorders. Further reports from non-dedicated centres treating patients with pelvic radiation disease will aid in understanding of secondary GI diagnoses and variation in practice.

Human Microbe-Disease Association Prediction by a Novel Double-Ended Random Walk with Restart

Microorganisms in the human body play a vital role in metabolism, immune defense, nutrient absorption, cancer control, and prevention of pathogen colonization. More and more biological and clinical studies have shown that the imbalance of microbial communities is closely related to the occurrence and development of various complex human diseases. Finding potential microbial-disease associations is critical for understanding the pathology of a few diseases and thus further improving disease diagnosis and prognosis. In this study, we proposed a novel computational model to predict disease-associated microbes. Specifically, we first constructed a heterogeneous interconnection network based on known microbe-disease associations deposited in a few databases, the similarity between diseases, and the similarity between microorganisms. We then predicted novel microbe-disease associations by a new method called the double-ended restart random walk model (DRWHMDA) implemented on the interconnection network. In addition, we performed case studies of colon cancer and asthma for further evaluation. The results indicate that 10 and 9 of the top 10 microorganisms predicted to be associated with colorectal cancer and asthma were validated by relevant literatures, respectively. Our method is expected to be effective in identifying disease-related microorganisms and will help to reveal the relationship between microorganisms and complex human diseases.

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.

Prevalence and duration of gastrointestinal symptoms before diagnosis of Inflammatory Bowel Disease and predictors of timely specialist review: a population-based study

BACKGROUND AND AIMS

Lack of timely referral and significant waits for specialist review amongst individuals with unresolved gastrointestinal (GI) symptoms can result in delayed diagnosis of Inflammatory Bowel Disease (IBD).

AIMS

To determine the frequency and duration of GI symptoms and predictors of timely specialist review before the diagnosis of both Crohn's Disease (CD) and ulcerative colitis (UC).

METHODS

Case-control study of IBD matched 1:4 for age and sex to controls without IBD using the Clinical Practice Research Datalink from 1998-2016.

RESULTS

We identified 19,555 cases of IBD, and 78,114 controls. 1 in 4 cases of IBD reported gastrointestinal symptoms to their primary care physician more than 6 months before receiving a diagnosis. There is a significant excess prevalence of GI symptoms in each of the 10 years before IBD diagnosis. GI symptoms were reported by 9.6% and 10.4% at 5 years before CD and UC diagnosis respectively compared to 5.8% of controls. Amongst patients later diagnosed with IBD, <50% received specialist review within 18 months from presenting with chronic GI symptoms. Patients with a previous diagnosis of irritable bowel syndrome or depression were less likely to receive timely specialist review (IBS: HR=0.77, 95%CI 0.60-0.99, depression: HR=0.77, 95%CI 0.60-0.98).

CONCLUSIONS

There is an excess of GI symptoms 5 years before diagnosis of IBD compared to the background population which are likely attributable to undiagnosed disease. Previous diagnoses of IBS and depression are associated with delays in specialist review. Enhanced pathways are needed to accelerate specialist referral and timely IBD diagnosis.

A symptom severity questionnaire for patients suffering from functional gastrointestinal disorder: FGI-Checklist

BACKGROUND AND AIM

A well-validated, comprehensive checklist of functional gastrointestinal (FGI) disorder (FGID) symptom severity for tracking symptom profile changes over time is lacking. We aim to develop and validate a comprehensive symptom severity checklist for FGID.

METHODS

A 20-item scale, including both upper and lower gastrointestinal symptoms, was generated to measure the symptom severity commonly found in FGID. Patients who experienced at least monthly symptoms of FGID with negative endoscopy findings were invited to complete the FGI-Checklist, Patient Health Questionaire-9 for assessing depressive symptoms, and Patient Health Questionnaire-15 for assessing somatic symptoms at baseline. A subset of patients who met Rome III diagnostic criteria of gastroesophageal reflux disease, functional dyspepsia, and irritable bowel syndrome received medication treatment for 8-12 weeks and completed the FGI-Checklist again at a follow-up visit. Exploratory factor analysis was performed for subscales formation and psychometric properties were measured.

RESULTS

Six hundred and forty-one patients were recruited for current study and 108 (16.8%) of them completed the FGI-Checklist again at follow-up. Exploratory factor analysis identified a five-factor solution accounting for 66.8% of the total variance. The five factors are named esophageal syndrome, reflux syndrome, functional dyspepsia syndrome, nausea and vomiting syndrome, and abdominal and bowel syndrome. The FGI-Checklist total score correlated with Patient Health Questionaire-9 and Patient Health Questionnaire-15 (all P < 0.001), which demonstrated good construct validity. Good item-internal consistency was found (Cronbach's alphas: 0.69-0.87). Responsiveness for reflux syndrome subscale, functional dyspepsia syndrome subscale, and abdominal and bowel syndrome subscale after medication treatment was significant (paired-t-test: all P < 0.01).

CONCLUSION

The instrument, Checklist, is valid and reliable.

Short-course Rifaximin therapy efficacy and lactulose hydrogen breath test in Chinese patients with diarrhea-predominant irritable bowel syndrome

Background

Gut microbiota alterations including small intestinal bacterial overgrowth (SIBO) might play a role in pathogenesis of irritable bowel syndrome (IBS). Rifaximin could effectively and safely improve IBS symptoms. The aim of this study was to investigate the effect of rifaximin on Gastrointestinal (GI) symptoms, quality of life (QOL) and SIBO eradication in Chinese IBS-D patients.

Methods

This study included 78 IBS-D patients defined by the Rome IV criteria. Patients received 400 mg rifaximin twice daily for 2 weeks and 10-week follow-up. GI symptoms were assessed at week 0, 2, 4, 8 and 12. QOL and lactulose hydrogen breath test (LHBT) results were estimated at week 0 and 4.

Results

All participants showed significant improvements in GI symptom subdomains after rifaximin treatment (all P < 0.05), which could maintain at least 10 weeks of follow-up. Additionally, QOL scores were increased with concomitant improvement of clinical symptoms (all P < 0.05). The 45 rifaximin-responsive patients (57.7%) achieved significantly greater GI-symptom improvement than non-responders (all P < 0.05). No GI symptoms were associated with SIBO (all P > 0.05). SIBO normalization after rifaximin treatment measured by LHBT was found in 44.4% (20/45) of patients with SIBO before treatment.

Conclusion

A short course (2 weeks) of rifaximin improved GI symptoms and QOL in Chinese IBS-D patients whether they had SIBO or not. However, the efficacy of rifaximin could not be explained by the successful eradication of SIBO. Further studies on the therapeutic mechanisms of rifaximin in IBS are urgently needed.

Metabolic syndrome, depression, and fibromyalgia syndrome prevalence in patients with irritable bowel syndrome: A case-control study

Although both metabolic syndrome (MetS) and irritable bowel syndrome (IBS) have been linked with altered gut microbiota, only a few studies investigated the association between them. Hence, we aimed to evaluate the prevalence of MetS along with depression and fibromyalgia syndrome (FMS) in IBS patients.This was a case-control study in which 3808 consecutive patients who attended outpatient clinics of Erzurum Regional Training and Research Hospital between May 2019 and August 2019 were evaluated in terms of IBS with Rome-IV criteria. Out of 486 patients who were diagnosed as IBS, 176 patients were excluded for various reasons. Control subjects were randomly selected from IBS-negative subjects. MetS was diagnosed based on International Diabetes Federation criteria. Depression, anxiety disorder, and FMS were assessed via Hamilton Depression Scale, Beck Anxiety Inventory, and American College of Rheumatology criteria, respectively. Blood samples were obtained to measure biochemical parameters.Study group included 310 IBS patients, and control group included 304 subjects. The prevalence of the MetS was significantly higher among IBS patients compared with controls (36.8% vs 21.7%, respectively, P = .006). The rate of obesity was 18.1% among IBS subjects, and 10.2% in the controls. The prevalence of fibromyalgia (30% vs 3%, respectively, P < .001), anxiety-disorder (39.7% vs 10.2%, P < .001) and depression (8.1% vs 4.9%, P < .001) were significantly higher in IBS group than controls.Metabolic syndrome and obesity were significantly more frequent in IBS patients compared with controls. FMS, anxiety disorder, and depression were also more common among IBS patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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