The pathogenesis of gastrointestinal bacterial overgrowth

Hospitalized patients on proton pump inhibitors for stress ulcer prophylaxis have a higher risk of Clostridioides difficile infection compared with those on histamine-2 receptor antagonists

BACKGROUND

Previous studies on Clostridioides difficile infection (CDI) in proton pump inhibitor (PPI) users generally enrolled a heterogeneous population and did not include a control group of histamine H2 receptor antagonists (H2RAs) users or adjust for confounding variables, such as previous antibiotics. It is uncertain whether hospitalized patients using PPIs for stress ulcer prophylaxis (SUP) are at a higher risk of CDI compared with those using H2RAs. This study aimed to compare the association between CDI and the usage of antisecretory drugs (ASDs): PPIs and H2RAs, for SUP among hospitalized patients, and the impact of the duration of their use on CDI.

METHODS

In this nationwide population-based cohort study using the Taiwan National Health Insurance Database, hospitalized patients using ASDs for SUP were identified between 2017 and 2018. A total of 63,266 and 69,269 individuals were included in the PPI and H2RA groups, respectively. The primary endpoint was a 90-day monitoring of CDI occurrence.

FINDINGS

The incidences of CDI were 1.6/10,000 and 0.5/10,000 person-days in the PPIs and H2RAs groups, respectively. After adjusting for confounding factors, the risk of infection in the PPIs group remained significantly higher than in the H2RAs group (hazard ratio (HR), 2.49; 95% confidence interval (CI), 1.63-3.81). In the subgroup analysis, during hospitalization, the risk of CDI for patients using high-risk antibiotics or admitted to the intensive care unit (ICU), as well as patients with immunodeficiency, using PPIs for SUP, was higher than using H2RAs. Furthermore, the risk of CDI was higher in patients using ASDs for durations >14 days than in those using them for <7 days (adjusted HR, 3.66; 95% CI, 2.34-5.75).

CONCLUSIONS

The risk of occurrence CDI for hospitalized patients using PPIs for SUP was higher than using H2RAs. It is recommended not to exceed 14 days of any gastric ASDs for SUP during hospitalization, especially for patients who have used high-risk antibiotics, have been admitted to the ICU, or have immunodeficiency.

Therapeutic potential of rifaximin in liver diseases

Rifaximin, derived from rifamycin, is a broad-spectrum antibiotic by inhibiting bacterial RNA synthesis. Rifaximin has a very low intestinal absorption and exerts its antimicrobial activity primarily in the intestinal tract. It regulates the gut microbiota with limited side effects systemically. Rifaximin has been recommended for the treatment of hepatic encephalopathy but some studies shed light on its medicinal effects in many other diseases. For instance, rifaximin may suppress the progression of liver fibrosis and its related complications, and ameliorate metabolic dysfunction-associated steatotic liver disease and alcohol-associated liver disease, etc. Rifaximin can also mediate anti-inflammation, antiproliferation, and proapoptotic events by activating pregnane X receptor, which is efficious in cancers such as colon cancer. In addition, some investigations have shown rifaximin may play a therapeutic role in various autoimmune and neurological disorders. However, these findings still need more real-world practices and in-depth investigations to obtain more precise indications and fully elucidate the multifaceted potentials of rifaximin.

Chronic atrophic gastritis and risk of incident upper gastrointestinal cancers: a systematic review and meta-analysis

BACKGROUND

Previous literature has explored the relationship between chronic atrophic gastritis (CAG) and isolated cancers within the upper gastrointestinal cancers; However, an integrative synthesis across the totality of upper gastrointestinal cancers was conspicuously absent. The research objective was to assess the relationship between CAG and the risk of incident upper gastrointestinal cancers, specifically including gastric cancer, oesophageal cancer, and oesophagogastric junction cancer.

METHODS

Rigorous systematic searches were conducted across three major databases, namely PubMed, Embase and Web of Science, encompassing the timeline from database inception until August 10, 2023. We extracted the necessary odds ratio (OR) and their corresponding 95% confidence interval (CI) for subsequent meta-analysis. Statistical analyses were conducted using Stata 17.0 software.

RESULTS

This meta-analysis included a total of 23 articles encompassing 5858 patients diagnosed with upper gastrointestinal cancers. CAG resulted in a statistically significant 4.12-fold elevated risk of incident gastric cancer (OR = 4.12, 95% CI 3.20-5.30). Likewise, CAG was linked to a 2.08-fold increased risk of incident oesophageal cancer (OR = 2.08, 95%CI 1.60-2.72). Intriguingly, a specific correlation was found between CAG and the risk of incident oesophageal squamous cell carcinoma (OR = 2.29, 95%CI 1.77-2.95), while no significant association was detected for oesophageal adenocarcinoma (OR = 0.62, 95%CI 0.17-2.26). Moreover, CAG was correlated with a 2.77-fold heightened risk of oesophagogastric junction cancer (OR = 2.77, 95%CI 2.21-3.46). Notably, for the same type of upper gastrointestinal cancer, it was observed that diagnosing CAG through histological methods was linked to a 33-77% higher risk of developing cancer compared to diagnosing CAG through serological methods.

CONCLUSION

This meta-analysis indicated a two- to fourfold increased risk of gastric cancer, oesophageal cancer, and oesophagogastric junction cancer in patients with CAG. Importantly, for the same upper gastrointestinal cancer, the risk of incident cancer was higher when CAG was diagnosed histologically compared to serological diagnosis. Further rigorous study designs are required to explore the impact of CAG diagnosed through both diagnostic methods on the risk of upper gastrointestinal cancers.

The gut microbiota and its biogeography

Biogeography is the study of species distribution and diversity within an ecosystem and is at the core of how we understand ecosystem dynamics and interactions at the macroscale. In gut microbial communities, a historical reliance on bulk sequencing to probe community composition and dynamics has overlooked critical processes whereby microscale interactions affect systems-level microbiota function and the relationship with the host. In recent years, higher-resolution sequencing and novel single-cell level data have uncovered an incredible heterogeneity in microbial composition and have enabled a more nuanced spatial understanding of the gut microbiota. In an era when spatial transcriptomics and single-cell imaging and analysis have become key tools in mammalian cell and tissue biology, many of these techniques are now being applied to the microbiota. This fresh approach to intestinal biogeography has given important insights that span temporal and spatial scales, from the discovery of mucus encapsulation of the microbiota to the quantification of bacterial species throughout the gut. In this Review, we highlight emerging knowledge surrounding gut biogeography enabled by the observation and quantification of heterogeneity across multiple scales.

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

BACKGROUND

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

METHODS

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

KEY RESULTS

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

CONCLUSIONS & INFERENCES

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

Antibiotic and antifungal use in pediatric leukemia and lymphoma patients are associated with increasing opportunistic pathogens and decreasing bacteria responsible for activities that enhance colonic defense

Due to decreased immunity, both antibiotics and antifungals are regularly used in pediatric hematologic-cancer patients as a means to prevent severe infections and febrile neutropenia. The general effect of antibiotics on the human gut microbiome is profound, yielding decreased diversity and changes in community structure. However, the specific effect on pediatric oncology patients is not well-studied. The effect of antifungal use is even less understood, having been studied only in mouse models. Because the composition of the gut microbiome is associated with regulation of hematopoiesis, immune function and gastrointestinal integrity, changes within the patient gut can have implications for the clinical management of hematologic malignancies. The pediatric population is particularly challenging because the composition of the microbiome is age dependent, with some of the most pronounced changes occurring in the first three years of life. We investigated how antibiotic and antifungal use shapes the taxonomic composition of the stool microbiome in pediatric patients with leukemia and lymphoma, as inferred from both 16S rRNA and metagenome data. Associations with age, antibiotic use and antifungal use were investigated using multiple analysis methods. In addition, multivariable differential abundance was used to identify and assess specific taxa that were associated with multiple variables. Both antibiotics and antifungals were linked to a general decline in diversity in stool samples, which included a decrease in relative abundance in butyrate producers that play a critical role in host gut physiology (e.g., Faecalibacterium, Anaerostipes, Dorea, Blautia),. Furthermore, antifungal use was associated with a significant increase in relative abundance of opportunistic pathogens. Collectively, these findings have important implications for the treatment of leukemia and lymphoma patients. Butyrate is important for gastrointestinal integrity; it inhibits inflammation, reinforces colonic defense, mucosal immunity. and decreases oxidative stress. The routine use of broad-spectrum anti-infectives in pediatric oncology patients could simultaneously contribute to a decline in gastrointestinal integrity and colonic defense while promoting increases in opportunistic pathogens within the patient gut. Because the gut microbiome has been linked to both short-term clinical outcomes, and longer-lasting health effects, systematic characterization of the gut microbiome in pediatric patients during, and beyond, treatment is warranted.

Helicobacter pylori infection and small intestinal bacterial overgrowth–more than what meets the eye

Helicobacter pylori (H. pylori) infection is very common and affects a significant proportion of the world population. In contrast, the prevalence of small intestinal bacterial overgrowth (SIBO) in the general population is not well understood. There can be coexistence of both disease states in a given patient and their clinical symptoms may also overlap with one and another. There is no clear clinical guidelines for testing for and treating SIBO in patients with H. pylori infection. This review article explores the available evidence on the relationship between H. pylori infection and SIBO, diagnosis and treatment of these entities and also comments on associated non-gastrointestinal conditions.

Effect of Enteral Immunonutrition in Patients Undergoing Surgery for Gastrointestinal Cancer: An Updated Systematic Review and Meta-Analysis

Background

The efficacy of enteral immunonutrition (EIN) in patients undergoing gastrointestinal cancer surgery remains debatable. This meta-analysis aimed to investigate the effectiveness of EIN administration in patients undergoing surgery for gastrointestinal cancer.

Methods

From January 2000 to January 2022, PubMed, EMBASE, Cochrane Library, and Web of Science were thoroughly searched for randomized controlled trials (RCTs) with EIN versus standard diet or no supplement in patients undergoing surgery for gastrointestinal cancer. Overall complications and infectious complications were the primary outcomes. The secondary results were non-infectious complications, mortality, length of hospital stay, and enteral nutrition-related complications.

Results

Thirty-five studies reporting 3,692 patients undergoing surgery for gastrointestinal cancer (including gastric cancer, colorectal cancer, esophageal cancer, periampullary cancer, or pancreatic cancer) were included. Compared with the control group, EIN group had a significantly decreased incidence of overall complications (RR = 0.79, p < 0.001). Infectious complications in patients who received EIN were considerably lower than in the control group (RR = 0.66, p < 0.001). Compared to the control group, the incidence of surgical site infection, abdominal abscess, anastomotic leakage, bacteremia, duration of systemic inflammatory response syndrome (SIRS), and duration of antibiotic therapy was significantly lower in the specific infectious complications treated with EIN. Still, there was no significant difference between the two groups with other infectious complications. Moreover, a substantial shortening in the length of hospital stay was shown in EIN group compared with the control group. Still, no significant effect of EIN was demonstrated in non-infectious complicatios and mortality. The enteral nutrition-related complications had no significant difference between two groups.

Conclusions

EIN is safe and effective in reducing overall complications, infectious complications, and hospital stay in patients undergoing gastrointestinal cancer surgery (including gastric cancer, colorectal cancer, esophageal cancer, periampullary cancer, or pancreatic cancer).

Characterisation of Lactobacillus plantarum of Dairy-Product Origin for Probiotic Chèvre Cheese Production

Probiotics are increasingly used as functional food ingredients. The objectives of this study were to isolate and characterise probiotic bacteria from dairy and fermented foods and to use a selected strain for the production of probiotic chèvre cheese. Tolerance to acid (pH 2.0) and bile salt (0.4% (w/v)) were first investigated, and then other probiotic properties were determined. Out of 241 isolates, 35 showed high tolerance to acid and bile salt, and 6 were chosen for further characterisation. They were Lactobacillus plantarum and L. fermentum, and possessed antibacterial activities against foodborne pathogens such as Bacillus cereus, Staphylococcus aureus, Salmonella enterica and Escherichia coli O157:H7. L. plantarum (isolate AD73) showed the highest percentage of adhesion (81.74 ± 0.16%) and was nontoxic to Caco-2 cells at a concentration of 108 CFU/mL. This isolate was therefore selected for the production of probiotic chèvre cheese from goat’s milk and was prepared in a lyophilised form with a concentration of probiotic culture of 8.6 log CFU/g. The cheese had a shelf life of 8 days. On the expiry date, the probiotic, the starter and the yeast contents were 7.56 ± 0.05, 7.81 ± 0.03 and 5.64 log CFU/g, respectively. The level of the probiotics in this chèvre cheese was still sufficiently high to warrant its being a probiotic cheese.

Non-pharmacological management of pediatric functional abdominal pain disorders: Current evidence and future perspectives

Functional abdominal pain disorders (FAPDs) are an important and prevalent cause of functional gastrointestinal disorders among children, encompassing the diagnoses of functional dyspepsia, irritable bowel syndrome, abdominal migraine, and the one not previously present in Rome III, functional abdominal pain not otherwise specified. In the absence of sufficiently effective and safe pharmacological treatments for this public problem, non-pharmacological therapies emerge as a viable means of treating these patients, avoiding not only possible side effects, but also unnecessary prescription, since many of the pharmacological treatments prescribed do not have good efficacy when compared to placebo. Thus, the present study provides a review of current and relevant evidence on non-pharmacological management of FAPDs, covering the most commonly indicated treatments, from cognitive behavioral therapy to meditation, acupuncture, yoga, massage, spinal manipulation, moxibustion, and physical activities. In addition, this article also analyzes the quality of publications in the area, assessing whether it is possible to state if non-pharmacological therapies are viable, safe, and sufficiently well-based for an appropriate and effective prescription of these treatments. Finally, it is possible to observe an increase not only in the number of publications on the non-pharmacological treatments for FAPDs in recent years, but also an increase in the quality of these publications. Finally, the sample selection of satisfactory age groups in these studies enables the formulation of specific guidelines for this age group, thus avoiding the need for adaptation of prescriptions initially made for adults, but for children use.

Re-examining chemically defined liquid diets through the lens of the microbiome

Trends in nutritional science are rapidly shifting as information regarding the value of eating unprocessed foods and its salutary effect on the human microbiome emerge. Unravelling the evolution and ecology by which humans have harboured a microbiome that participates in every facet of health and disease is daunting. Most strikingly, the host habitat has sought out naturally occurring foodstuff that can fulfil its own metabolic needs and also the needs of its microbiota, each of which remain inexorably connected to one another. With the introduction of modern medicine and complexities of critical care, came the assumption that the best way to feed a critically ill patient is by delivering fibre-free chemically defined sterile liquid foods (that is, total enteral nutrition). In this Perspective, we uncover the potential flaws in this assumption and discuss how emerging technology in microbiome sciences might inform the best method of feeding malnourished and critically ill patients.

Bacterial Translocation as Inflammatory Driver in Crohn's Disease

Crohn’s disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract responsible for intestinal lesions. The multifactorial etiology attributed to CD includes a combination of environmental and host susceptibility factors, which result in an impaired host–microbe gut interaction. Bacterial overgrowth and dysbiosis, increased intestinal barrier permeability, and altered inflammatory responses in patients with CD have been described in the past. Those events explain the pathogenesis of luminal translocation of bacteria or its products into the blood, a frequent event in CD, which, in turn, favors a sustained inflammatory response in these patients. In this review, we navigate through the interaction between bacterial antigen translocation, permeability of the intestinal barrier, immunologic response of the host, and genetic predisposition as a combined effect on the inflammatory response observed in CD. Several lines of evidence support that translocation of bacterial products leads to uncontrolled inflammation in CD patients, and as a matter of fact, the presence of gut bacterial genomic fragments at a systemic level constitutes a marker for increased risk of relapse among CD patients. Also, the significant percentage of CD patients who lose response to biologic therapies may be influenced by the translocation of bacterial products, which are well-known drivers of proinflammatory cytokine production by host immune cells. Further mechanistic studies evaluating cellular and humoral immune responses, gut microbiota alterations, and genetic predisposition will help clinicians to better control and personalize the management of CD patients in the future.

Helicobacter pylori and colorectal neoplasms: a concise review

Helicobacter pylori is the main etiological agent of all malignant tumors caused by an infectious disease. It is a major, at times dominant, factor in the pathogenesis of a large spectrum of diseases such as acute and chronic gastritis, gastric and duodenal ulcers, gastric carcinoma, and lymphoma. Epidemiological and experimental studies suggest that H. pylori chronic infection may be related to different extragastric diseases, including colorectal neoplasms. This concise review aims to explore the association of H. pylori infection with colorectal cancer and adenoma, including the recent epidemiological findings, the diagnostic methods employed to detect H. pylori and virulent factors, and the potentially involved mechanisms. Furthermore, is attempted to establish the current data integration for causal inference using the Bradford-Hill causality criteria. The weak, although global, strength of the epidemiological positive association between H. pylori infection and colonic neoplasms associated to new mechanisms postulated to explain this interaction, including intestinal dysbiosis, should stimulate future studies. Prospective confirmatory studies to establish the role of H. pylori eradication in the process of carcinogenic transformation of the colonic epithelium may define its eventual role in the treatment and prevention of colonic neoplasms.

Risk Factors for Renal Impairment in Adult Patients With Short Bowel Syndrome

Renal impairment is a common complication in patients with intestinal failure that is mostly caused by short bowel syndrome (SBS) and is associated with adverse outcomes that severely affect the quality of life or even survival. The prevalence and risk factors for renal impairment in patients with SBS remain unclarified. Therefore, we aimed to determine the prevalence of renal impairment and identify potential risk factors for renal impairment in adult patients with SBS. We retrospectively identified 199 patients diagnosed with SBS admitted to the Department of General Surgery between January 1, 2012 and January 1, 2019, from a prospectively maintained database. Overall, 56 patients (28.1%) with decreased renal function (eGFR < 90 mL/min/1.73 m²). The median duration of SBS was 7 months (IQR, 3-31 months) and the mean eGFR was 103.1 ± 39.4 mL/min/1.73 m². Logistic regression modeling indicated that older age [odds ratio (OR), 1.074; 95% CI, 1.037-1.112, P < 0.001], kidney stones (OR, 4.887; 95% CI, 1.753-13.626; P = 0.002), decreased length of the small intestine (OR, 0.988; 95% CI, 0.979-0.998; P = 0.019), and prolonged duration of SBS (OR, 1.007; 95% CI, 1.001-1.013; P = 0.046) were significant risk factors for renal impairment. This is the largest study that has specifically explored the risk factors for renal impairment in a large cohort of adults with SBS. The present study showed that renal function should be closely monitored during treatment, and patients should be given prophylactic interventions if necessary. This retrospective study is a part of clinical study NCT03277014, registered in ClinicalTrials.gov PRS. And the PRS URL is http://register.clinicaltrials.gov.

Chronic diarrhoea in an oncology patient - Clinical assessment and decision making

Cancer survival is improving rapidly due to advances in treatments that will often involve radiotherapy, chemotherapy and novel biological agents in addition to surgery. This comes at the price of living with chronic symptoms, of which diarrhoea is particularly common. There is good evidence that for many patients these symptoms become part of everyday life, their "normality" is adjusted and symptoms are tolerated even when limiting activities severely. Clinicians often fail to appreciate the impact of these problems, as the focus of follow up tends to be on cancer recurrence. However, the rapid identification of patients in significant trouble can lead to earlier diagnosis of treatable pathologies and improvement of patients' symptoms. The aim of this review is to highlight the mechanisms which cause oncology patients to develop diarrhoea and highlight useful investigational and treatment strategies.

[The role of the gut microbiome in idiopathic Parkinson's disease]

BACKGROUND

In recent years studies have provided increasing evidence suggesting an association between the (gut) microbiome and idiopathic Parkinson's disease (IPD).

OBJECTIVE

The aim of this article is to summarize and evaluate existing evidence with respect to the relevance of the (gut) microbiome for IPD.

MATERIAL AND METHODS

An analysis and critical review of studies in the field of IPD and (gut) microbiome were carried out. The resulting potential perspectives and therapeutic strategies are discussed.

RESULTS

Despite partially divergent results between different studies (potentially due to the applied methods and variance in the composition of the investigated cohorts), there is an overlap between studies indicating an association between IPD, the microbiome and microbial metabolites. Nevertheless, the cause-effect relationship between IPD and the microbiome has still not been clarified. Taken together, existing evidence supports a potentially relevant role for the microbiome with respect to typical disease symptoms and pathogenesis of the disease.

CONCLUSION

Over the past 5 years there has been an enormous increase in the evidence with respect to the relevance of the microbiome for IPD. While early work in this field was mainly descriptive, new diagnostic methods provide evidence for the underlying mechanisms and the complex interactions between man as the host, the human immune system, the enteric nervous system, gut microbiota and microbial metabolites. A relatively novel and clinically relevant field of research is how the gut microbiome can influence the success of oral pharmacotherapy and whether substitution of specific microbiome components might be used either for future therapeutic or prophylactic strategies.

Choline in cystic fibrosis: relations to pancreas insufficiency, enterohepatic cycle, PEMT and intestinal microbiota

BACKGROUND

Cystic Fibrosis (CF) is an autosomal recessive disorder with life-threatening organ manifestations. 87% of CF patients develop exocrine pancreas insufficiency, frequently starting in utero and requiring lifelong pancreatic enzyme substitution. 99% develop progressive lung disease, and 20-60% CF-related liver disease, from mild steatosis to cirrhosis. Characteristically, pancreas, liver and lung are linked by choline metabolism, a critical nutrient in CF. Choline is a tightly regulated tissue component in the form of phosphatidylcholine (Ptd'Cho) and sphingomyelin (SPH) in all membranes and many secretions, particularly of liver (bile, lipoproteins) and lung (surfactant, lipoproteins). Via its downstream metabolites, betaine, dimethylglycine and sarcosine, choline is the major one-carbon donor for methionine regeneration from homocysteine. Methionine is primarily used for essential methylation processes via S-adenosyl-methionine.

CLINICAL IMPACT

CF patients with exocrine pancreas insufficiency frequently develop choline deficiency, due to loss of bile Ptd'Cho via feces. ~ 50% (11-12 g) of hepatic Ptd'Cho is daily secreted into the duodenum. Its re-uptake requires cleavage to lyso-Ptd'Cho by pancreatic and small intestinal phospholipases requiring alkaline environment. Impaired CFTR-dependent bicarbonate secretion, however, results in low duodenal pH, impaired phospholipase activity, fecal Ptd'Cho loss and choline deficiency. Low plasma choline causes decreased availability for parenchymal Ptd'Cho metabolism, impacting on organ functions. Choline deficiency results in hepatic choline/Ptd'Cho accretion from lung tissue via high density lipoproteins, explaining the link between choline deficiency and lung function. Hepatic Ptd'Cho synthesis from phosphatidylethanolamine by phosphatidylethanolamine-N-methyltransferase (PEMT) partly compensates for choline deficiency, but frequent single nucleotide polymorphisms enhance choline requirement. Additionally, small intestinal bacterial overgrowth (SIBO) frequently causes intraluminal choline degradation in CF patients prior to its absorption. As adequate choline supplementation was clinically effective and adult as well as pediatric CF patients suffer from choline deficiency, choline supplementation in CF patients of all ages should be evaluated.

The Influence of Small Intestinal Bacterial Overgrowth in Digestive and Extra-Intestinal Disorders

Small intestinal bacterial overgrowth (SIBO) is a condition hallmarked by an increase in the concentration of colonic-type bacteria in the small bowel. Watery diarrhea, bloating, abdominal pain and distension are the most common clinical manifestations. Additionally, malnutrition and vitamin (B12, D, A, and E) as well as minerals (iron and calcium) deficiency may be present. SIBO may mask or worsen the history of some diseases (celiac disease, irritable bowel disease), may be more common in some extra-intestinal disorders (scleroderma, obesity), or could even represent a pathogenetic link with some diseases, in which a perturbation of intestinal microbiota may be involved. On these bases, we performed a review to explore the multiple links between SIBO and digestive and extra-intestinal diseases.

Increased Colonic Permeability and Lifestyles as Contributing Factors to Obesity and Liver Steatosis

Intestinal permeability (IP) is essential in maintaining gut-metabolic functions in health. An unequivocal evaluation of IP, as marker of intestinal barrier integrity, however, is missing in health and in several diseases. We aimed to assess IP in the whole gastrointestinal tract according to body mass index (BMI) and liver steatosis. In 120 patients (61F:59M; mean age 45 ± SEM 1.2 years, range: 18-75), IP was distinctively studied by urine recovery of orally administered sucrose (SO, stomach), lactulose/mannitol ratio (LA/MA, small intestine), and sucralose (SA, colon). By triple quadrupole mass-spectrometry and high-performance liquid chromatography, we measured urinary recovery of saccharide probes. Subjects were stratified according to BMI as normal weight, overweight, and obesity, and answered questionnaires regarding dietary habits and adherence to the Mediterranean Diet. Liver steatosis was assessed by ultrasonography. IP at every gastrointestinal tract was similar in both sexes and decreased with age. Stomach and small intestinal permeability did not differ according to BMI. Colonic permeability increased with BMI, waist, neck, and hip circumferences and was significantly higher in obese than in lean subjects. As determined by logistic regression, the odds ratio (OR) of BMI increment was significantly higher in subjects in the highest tertile of sucralose excretion, also after adjusting for age and consumption of junk food. The presence of liver steatosis was associated with increased colonic permeability. Patients with lower score of adherence to Mediterranean diet had a higher score of 'junk food'. Intestinal permeability tended to increase in subjects with a lower adherence to Mediterranean diet. In conclusion, colonic (but not stomach and small intestinal) permeability seems to be linked to obesity and liver steatosis independently from dietary habits, age, and physical activity. The exact role of these last factors, however, requires specific studies focusing on intestinal permeability. Results should pave the way to both primary prevention measures and new therapeutic strategies in metabolic and liver diseases.

Risk Factors Associated With Upper Aerodigestive Tract or Coliform Bacterial Overgrowth of the Small Intestine in Symptomatic Patients

INTRODUCTION

The clinical relevance of bacterial types identified in small bowel aspirate cultures during diagnostic evaluation of small intestinal bacterial overgrowth (SIBO) is unclear.

AIM

The main purpose of this study was to assess associations between risk factors for upper aerodigestive tract (UAT) or coliform SIBO and SIBO diagnosis by culture.

MATERIALS AND METHODS

Small bowel aspirates were cultured in patients with suspected SIBO, defined as ≥10 colony-forming units/mL coliform or ≥10 colony-forming units/mL UAT bacteria. History was reviewed for risk factors and potential SIBO complications. Symptoms, quality of life, psychological traits, and laboratory values were assessed. We compared groups by 2-sample t test, Wilcoxon rank sum test, and the Fisher exact test. Overall associations of primary and secondary endpoints with type of bacterial overgrowth were assessed by analysis of variance F-test, Kruskal-Wallis test, and the Fisher exact tests. Associations of risk factors with type of overgrowth were explored using multinomial logistic regression.

RESULTS

Among 76 patients, 37 had SIBO (68% coliform, 33% UAT) and 39 did not. Conditions (P=0.02) and surgery (P<0.01) associated with decreased gastric acid were associated with SIBO. In multinomial logistic regression, conditions of decreased acid was associated with UAT SIBO [odds ratio (OR), 5.8; 95% confidence interval, 1.4-33.3]. Surgery causing decreased acid was associated with UAT [OR, 9.5 (1.4-106)] and coliform SIBO [OR, 8.4 (1.6-86.4)]. Three patients with discontinuous small bowel had coliform SIBO [OR, 17.4 (1.2-2515)]. There were no differences in complications, overall symptoms, quality of life, or psychological traits.

CONCLUSIONS

Conditions or surgeries associated with decreased gastric acid are associated with SIBO diagnosis by culture.

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Systematic review with meta-analysis: the prevalence of small intestinal bacterial overgrowth in inflammatory bowel disease

BACKGROUND

Current data on small intestinal bacterial overgrowth (SIBO) in patients with inflammatory bowel diseases (IBD) are controversial.

AIM

To conduct a systematic review and meta-analysis to determine the prevalence of SIBO in patients with ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

Electronic databases were searched up to May 2018 for studies reporting prevalence of SIBO in IBD patients. The prevalence rate of SIBO among IBD patients and the odds ratio (OR) and 95% CI of SIBO in IBD patients compared with controls were calculated.

RESULTS

The final dataset included 11 studies (1175 adult patients with IBD and 407 controls), all utilising breath test for diagnosis of SIBO. The proportion of SIBO in IBD patients was 22.3% (95% CI 19.92-24.68). The OR for SIBO in IBD patients was 9.51 (95% CI 3.39-26.68) compared to non-IBD controls, and high in both CD (OR = 10.86; 95% CI 2.76-42.69) and UC (OR = 7.96; 95% CI 1.66-38.35). In patients with CD, subgroup analysis showed the presence of fibrostenosing disease (OR = 7.47; 95% CI 2.51-22.20) and prior bowel surgery (OR = 2.38; 95% CI 1.65-3.44), especially resection of the ileocecal valve, increased the odds of SIBO. Individual studies suggest that combined small and large bowel disease but not disease activity may be associated with SIBO.

CONCLUSIONS

Overall, there is a substantial increase in the prevalence of SIBO in IBD patients compared to controls. Prior surgery and the presence of fibrostenosing disease are risk factors for SIBO in IBD.

Chronic diarrhoea following surgery for colon cancer-frequency, causes and treatment options

PURPOSE

The growing population of survivors after colon cancer warrants increased attention to the long-term outcome of surgical treatment. The change in bowel anatomy after resection disrupts normal gastrointestinal function and may cause symptoms. Thus, many patients surviving colon cancer have to cope with bowel dysfunction for the rest of their lives. We here aim to provide an overview of the literature on this topic.

METHODS

We review long-term functional outcomes of surgical treatment for colon cancer, the underlying pathology, and treatment options.

RESULTS

Common symptoms include constipation, urge for defecation and diarrhoea. Causes of diarrhoea after colon cancer surgery are sparsely studied, but they probably include bile acid malabsorption, small intestinal bacterial overgrowth and disruption of the ileal brake. Specific diagnosis should be made to allow individual treatment based on the underlying pathology. Studies on treatment of functional problems after surgery for colon cancer are extremely few, but some lessons can be drawn from the treatment of other patient groups having undergone colon surgery.

CONCLUSION

Diarrhoea is likely a common long-term complication after colon cancer surgery. Attention to this complication and a specific diagnosis will aid the targeted treatment of patients suffering from this complication.

Contractile effect of rifaximin on bovine uterus in the presence of steroid hormone antagonists

This in vitro study investigated the modulatory effect of rifaximin on bovine uterus contractility, in both phases of the oestrous cycle, with and without the steroid hormones that are predominant in the respective phases: oestrogen in the follicular phase and progesterone in the luteal phase. The procedures were conducted in an isolated organ bath by using rifaximin alone (10^-4 M) and in association with the steroid hormone antagonists (10^-5 M) tamoxifen (oestrogen antagonist) in the follicular phase and mifepristone (progesterone antagonist) in the luteal phase. The results indicated that rifaximin can stimulate uterine contractility. Indeed, the administration of rifaximin in the presence of tamoxifen or mifepristone increased the tonic activity of the uterus in both phases of the cycle. This result is clinically significant because rifaximin might also enable, in vivo, a simultaneous increase in uterine cleaning and the antimicrobial action against bacteria during the first 14 days postpartum, during the development of acute metritis.

Small Intestinal Bacterial Overgrowth Affects the Responsiveness to Colchicine in Familial Mediterranean Fever

Objective

Familial Mediterranean fever (FMF) is an autosomal recessive disease due to a MEFV gene mutation. Since Helicobacter pylori infection has been described to increase the severity and frequency of FMF attacks, we evaluate if overgrowth of small intestinal bacterial (SIBO), associated with a release of bacterial products, can affect the response to colchicine in FMF patients poorly responsive to colchicine.

Methods

We revised our Periodic Fever Centre database to detect FMF patients who were poorly responsive to colchicine, without a well-defined cause of drug resistance. They were evaluated for SIBO presence, then treated with decontamination therapy.

Results

Among 223 FMF patients, 49 subjects show colchicine resistance, and no other known causes of colchicine unresponsiveness has been found in 25 patients. All 25 patients underwent glucose breath test; 20 (80%) of them were positive, thus affected by SIBO. After a successful decontamination treatment, 11 patients (55%) did not show FMF attacks during the following three months (p < 0.01), while 9 of them revealed a significant reduction of the number of attacks compared to three months before (p < 0.01).

Conclusion

The SIBO eradication improves laboratory and clinical features of FMF patients. Thus, patients with unresponsiveness to colchicine treatment should be investigated for SIBO.

Small Intestinal Bacterial Overgrowth and Other Intestinal Disorders

Gut microbiota is the largest organ of the human body. Although growth of bacteria more than 10⁵ colony forming unit (CFU) per milliliter in culture of upper gut aspirate is used to diagnosis small intestinal bacterial overgrowth (SIBO), 10³ CFU or more is being considered to suggest the diagnosis, particularly if colonic type bacteria are present in the upper gut. Although neither very sensitive nor specific, hydrogen breath tests are widely used to diagnose SIBO. Rifaximin is the best treatment for SIBO due to its broad spectrum, lack of systemic absorption, and safety profile.

Rethinking the role of alpha toxin in Clostridium perfringens-associated enteric diseases: a review on bovine necro-haemorrhagic enteritis

Bovine necro-haemorrhagic enteritis is an economically important disease caused by Clostridium perfringens type A strains. The disease mainly affects calves under intensive rearing conditions and is characterized by sudden death associated with small intestinal haemorrhage, necrosis and mucosal neutrophil infiltration. The common assumption that, when causing intestinal disease, C. perfringens relies upon specific, plasmid-encoded toxins, was recently challenged by the finding that alpha toxin, which is produced by all C. perfringens strains, is essential for necro-haemorrhagic enteritis. In addition to alpha toxin, other C. perfringens toxins and/or enzymes might contribute to the pathogenesis of necro-haemorrhagic enteritis. These additional virulence factors might contribute to breakdown of the protective mucus layer during initial stage of pathogenesis, after which alpha toxin, either or not in synergy with other toxins such as perfringolysin O, can act on the mucosal tissue. Furthermore, alpha toxin alone does not cause intestinal necrosis, indicating that other virulence factors might be needed to cause the extensive tissue necrosis observed in necro-haemorrhagic enteritis. This review summarizes recent research that has increased our understanding of the pathogenesis of bovine necro-haemorrhagic enteritis and provides information that is indispensable for the development of novel control strategies, including vaccines.

Diagnosis and treatment of small intestinal bacterial overgrowth

A huge number of bacteria are hosted in the gastrointestinal tract, following a gradient increasing towards the colon. Gastric acid secretion and intestinal clearance provide the qualitative and quantitative partitioning of intestinal bacteria; small intestinal bacteria overgrowth (SIBO) occurs when these barrier mechanisms fail. Diagnosis of SIBO is challenging due to the low specificity of symptoms, the frequent association with other diseases of the gastrointestinal tract and the absence of optimal objective diagnostic tests. The therapeutic approach to SIBO is oriented towards resolving predisposing conditions, and is supported by antibiotic treatment to restore the normal small intestinal microflora and by modifications of dietary habits for symptomatic relief. In the near future, metagenomics and metabolomics will help to overcome the uncertainties of SIBO diagnosis and the pitfalls of therapeutic management, allowing the design of a personalized strategy based on the direct insight into the small intestinal microbial community.

Functional 13C-urea and glucose hydrogen/methane breath tests reveal significant association of small intestinal bacterial overgrowth in individuals with active Helicobacter pylori infection

OBJECTIVES

Helicobacter pylori infection is considered to alter the bacterial flora in the upper gastrointestinal tract. This study aimed at investigating the presence of small intestinal bacterial overgrowth (SIBO) in patients with active H. pylori infection assessed by functional breath testing.

DESIGN AND METHODS

A total of 109 outpatients, who were referred for the H. pylori¹³C-urea breath test (¹³C-UBT) by general practitioners and specialists, were also tested for the presence of SIBO by the glucose hydrogen (H₂)/methane (CH₄) breath test (HMBT). A detailed anamnesis was carried out about the history of H. pylori infection, eradication therapies, proton pump inhibitor intake, and comorbidities.

RESULTS

In total, 36/109 (33.0%) patients had a positive H. pylori¹³C-UBT, and 35/109 (32.1%) patients had a positive glucose HMBT, the latter being indicative of SIBO. Interestingly, individuals with a positive H. pylori¹³C-UBT were significantly more often associated with a positive glucose HMBT (p=0.002). Cohen's κ measuring agreement between the ¹³C-UBT and the glucose HMBT was 0.31 (confidence intervals: 0.12-0.50) (p=0.001). Altogether, 19 of 54 (35.2%) patients, who had completed up to four eradication therapies, were diagnosed with SIBO by HMBT.

CONCLUSIONS

H. pylori infection was found to be significantly associated with the presence of SIBO as determined by functional breath testing. In addition, SIBO rates appeared to have increased after completed eradication therapies. However, further longitudinal studies are warranted to fully elucidate the relationship and treatment modalities of coincident H. pylori infection and SIBO.

Predicting a Response to Antibiotics in Patients with the Irritable Bowel Syndrome

BACKGROUND

Antibiotics for presumed small intestinal bacterial overgrowth have been shown to improve irritable bowel syndrome symptoms in at least 40% of subjects. A lactulose breath test for small intestinal bacterial overgrowth has been used to select patients who will respond. However, its predictive value, using the classic definition of a positive lactulose breath test, has been disappointing.

AIMS

We conducted a retrospective evaluation to study characteristics of the lactulose breath test that may be predictive of a response to antibiotics in patients with the irritable bowel syndrome.

METHODS

A clinical practice database was interrogated for consecutive patients who had a lactulose breath test for irritable bowel syndrome symptoms and a subsequent antibiotic course. Hydrogen + methane levels with carbon dioxide correction were plotted against time. Various profiles of the breath test curves were catalogued and compared with respect to their predictive value for symptom response to antibiotics.

RESULTS

Lactulose breath test graphs of 561 patients of all irritable bowel syndrome subtypes were grouped into categories based on their hydrogen + methane levels with respect to time. Of subjects whose hydrogen + methane rise was <20 ppm throughout the test (group 1; N = 95), 94.7% improved after antibiotics (95% CI 90.1-99.3). Of those with a rise <20 ppm within the first 90 min but a rise >50 ppm thereafter (group 3; N = 53), 47.2% improved (95% CI 33.7-60.6). The difference between groups 1 and 3 was statistically significant P < 0.001.

CONCLUSION

A lactulose breath test appears to be useful in predicting response to antibiotics in patients with the irritable bowel syndrome. A hydrogen + methane rise <20 ppm throughout the duration of the test is most predictive. This observation contradicts the classic definition of a positive lactulose breath test.

Nod2-Rip2 Signaling Contributes to Intestinal Injury Induced by Muramyl Dipeptide Via Oligopeptide Transporter in Rats

BACKGROUND AND AIMS

PepT1 can transport bacterial oligopeptide products and induce intestinal inflammation. Our aim was to investigate the mechanism of the small intestine injury induced by bacterial oligopeptide product muramyl dipeptide (MDP) which is transported by PepT1.

METHODS

We perfused the jejunum with a solution with or without MDP, or with a solution of MDP + Gly-Gly and explored the degree of inflammation to determine the role of PepT1-Nod2 signaling pathway in small intestine mucosa.

RESULTS

MDP perfusion induced inflammatory cell accumulation and intestinal damage, accompanied by an increase in mucosal Nod2 and Rip2 transcript expression. NFκB activity and inflammatory cytokine expression, including serum levels of TNF-α, IL-1β, and IL-6, increased in the MDP group compared to the controls; these effects were reversed by perfusion of the nutritional dipeptide Gly-Gly.

CONCLUSION

MDP can be transported through PepT1, causing inflammatory damage in the rat small intestine. Nod2-Rip2-NFκB signaling involved in the small intestinal inflammatory injury caused by MDP which is transported through PepT1.

The chronic use of beta-blockers and proton pump inhibitors may affect the rate of bacterial infections in cirrhosis

BACKGROUND & AIMS

Bacterial infections are among the most common and life-threatening complications in cirrhosis. Qualitative and quantitative modifications of the gut microbiota, dysfunction of the intestinal barrier and multiple immune defects are factors that contribute to a pathological 'bacterial translocation' (BT), leading to a higher susceptibility to infections in cirrhotic patients. Long-term therapies, commonly adopted in cirrhotic patients, may influence BT and modify the risk of infection in these patients. To investigate the influence of chronic therapies on the prevalence and microbiological characteristics of infections in cirrhosis.

METHODS

Consecutive cirrhotic patients hospitalised from 2008 to 2013 were enrolled. All previous treatments were carefully recorded. Infections were actively sought out, patients were actively monitored for infection, and possible risk factors were evaluated.

RESULTS

Four hundred cirrhotic patients were included. The most frequent therapies were proton pump inhibitors (PPIs) (67%), non-absorbable-disaccharides (44%), beta-blockers (BBs) (39%) and non-absorbable-antibiotics (10%). Child-Pugh C (P < 0.001; OR 5; 95%CI: 2.6-9.9) and PPI therapy (P = 0.008; OR 2; 95% CI: 1.2-3.2) were found to be independent predictors of infection, and the use of BBs was a protective factor (P = 0.001; OR 0.46; 95%CI: 0.3-0.7). Cirrhotic patients with bacterial infection showed lower morbidity and mortality when taking BBs.

CONCLUSIONS

Proton pump inhibitors increase the risk of infection in cirrhosis and should not be prescribed in these patients without specific indications. In contrast, the use of BBs is associated with a lower rate of infection and attenuates the consequences of infections in cirrhotic patients.

Intestinal Microbiome, Small Intestinal Bacterial Overgrowth and Inflammatory Bowel Diseases - What are the Connections?

IBD (inflammatory bowel diseases) represent chronic idiopathic inflammatory diseases, prone to relapse in the digestive tract; it is estimated that they result from the interaction of the intestinal microbiome with the intestinal immune system. The inflammatory microbiome exerts multiple beneficial roles. Perhaps the central element to developing IBD is dysbiosis; there is still an incompletely established association between intestinal microbiome changes in patients with IBD and SIBO (small intestinal bacterial overgrowth). Influencing the intestinal microbiome may play an adjuvant therapeutic role in the treatment of IBD. We present a synthesis of the connections between the entities mentioned above.

Gastric diverticulum and halitosis-A case for surgery?

INTRODUCTION

Gastric diverticulum is a rare and frequently asymptomatic condition. Symptoms include vague pain, fullness, dyspepsia, vomiting, hemorrhage and perforation. Occasionally, the patient can present with belching and oral fetor.

PRESENTATION OF CASE

We report a 58-year-old woman with a gastric diverticulum who was suffering from a socially disabling oral fetor. After a thorough evaluation, a laparoscopic resection of the diverticulum was offered and completed successfully. At follow-up, the oral fetor had disappeared. The patient had no complaints and regarded herself as cured.

DISCUSSION

Although indications for the treatment of asymptomatic patients remain to be defined, pharmacological therapies including protein pump inhibitors and histamine receptor blockers have been employed, with limited effects in patients with miscellaneous symptoms. Surgery is required when serious complications such as hemorrhage or perforation of the diverticulum occur.

CONCLUSION

Surgery is required when serious complications such as hemorrhage or perforation of the diverticulum occur. Therapy resistent social disabling oral fetor may add to the indications for surgery.

A case of colonic pseudoobstruction related to bacterial overgrowth due to a sigmoidocecal fistula

Colocolic fistulas are usually a complication of an inflammatory or neoplastic process. Development of these abnormal bowel communications may lead to bacterial overgrowth. We report on a 71-year-old man with a one-year history of recurrent abdominal distension and irregular bowel habits. Abdominal X-rays and computed tomography showed multiple air-fluid levels and loops of distended bowel without evidence of mechanical obstruction or diverticulitis. Colonoscopy showed a fistulous tract between the sigmoid colon and cecum. Results of a lactulose breath test showed high fasting breath CH4 levels, which were thought to be the result of intestinal bacterial overgrowth. The patient was diagnosed with a colonic pseudo-obstruction associated with bacterial overgrowth due to a sigmoidocecal fistula. We recommended surgical correction of the sigmoidocecal fistula; however, the patient requested medical treatment. After antibiotic therapy, the patient still had mild symptoms but no acute exacerbations.

Laboratory diagnostics of spontaneous bacterial peritonitis

The term peritonitis indicates an inflammatory process involving the peritoneum that is most frequently infectious in nature. Primary or spontaneous bacterial peritonitis (SBP) typically occurs when a bacterial infection spreads to the peritoneum across the gut wall or mesenteric lymphatics or, less frequently, from hematogenous transmission in combination with impaired immune system and in absence of an identified intra-abdominal source of infection or malignancy. The clinical presentation of SBP is variable. The condition may manifest as a relatively insidious colonization, without signs and symptoms, or may suddenly occur as a septic syndrome. Laboratory diagnostics play a pivotal role for timely and appropriate management of patients with bacterial peritonitis. It is now clearly established that polymorphonuclear leukocyte (PMN) in peritoneal fluid is the mainstay for the diagnosis, whereas the role of additional biochemical tests is rather controversial. Recent evidence also suggests that automatic cell counting in peritoneal fluid may be a reliable approach for early screening of patients. According to available clinical and laboratory data, we have developed a tentative algorithm for efficient diagnosis of SBP, which is based on a reasonable integration between optimization of human/economical resources and gradually increasing use of invasive and expensive testing. The proposed strategy entails, in sequential steps, serum procalcitonin testing, automated cell count in peritoneal fluid, manual cell count in peritoneal fluid, peritoneal fluid culture and bacterial DNA testing in peritoneal fluid.

Selective decontamination of the digestive tract in gastrointestinal surgery: useful in infection prevention? A systematic review

INTRODUCTION

Gastrointestinal surgery is associated with a high incidence of infectious complications. Selective decontamination of the digestive tract is an antimicrobial prophylaxis regimen that aims to eradicate gastrointestinal carriage of potentially pathogenic microorganisms and represents an adjunct to regular prophylaxis in surgery.

MATERIAL AND METHODS

Relevant studies were identified using bibliographic searches of MEDLINE, EMBASE, and the Cochrane database (period from 1970 to November 1, 2012). Only studies investigating selective decontamination of the digestive tract in gastrointestinal surgery were included.

RESULTS

Two randomized clinical trials and one retrospective case-control trial showed significant benefit in terms of infectious complications and anastomotic leakage in colorectal surgery. Two randomized controlled trials in esophageal surgery and two randomized clinical trials in gastric surgery reported lower levels of infectious complications.

CONCLUSION

Selective decontamination of the digestive tract reduces infections following esophageal, gastric, and colorectal surgeries and also appears to have beneficial effects on anastomotic leakage in colorectal surgery. We believe these results provide the basis for a large multicenter prospective study to investigate the role of selective decontamination of the digestive tract in colorectal surgery.

The cystic fibrosis intestine

The clinical manifestations of cystic fibrosis (CF) result from dysfunction of the cystic fibrosis transmembrane regulator protein (CFTR). The majority of people with CF have a limited life span as a consequence of CFTR dysfunction in the respiratory tract. However, CFTR dysfunction in the gastrointestinal (GI) tract occurs earlier in ontogeny and is present in all patients, regardless of genotype. The same pathophysiologic triad of obstruction, infection, and inflammation that causes disease in the airways also causes disease in the intestines. This article describes the effects of CFTR dysfunction on the intestinal tissues and the intraluminal environment. Mouse models of CF have greatly advanced our understanding of the GI manifestations of CF, which can be directly applied to understanding CF disease in humans.

Antimicrobial peptides and gut microbiota in homeostasis and pathology

We survive because we adapted to a world of microorganisms. All our epithelial surfaces participate in keeping up an effective barrier against microbes while not initiating ongoing inflammatory processes and risking collateral damage to the host. Major players in this scenario are antimicrobial peptides (AMPs). Such broad-spectrum innate antibiotics are in part produced by specialized cells but also widely sourced from all epithelia as well as circulating inflammatory cells. AMPs belong to an ancient defense system found in all organisms and participated in a preservative co-evolution with a complex microbiome. Particularly interesting interactions between host barrier and microbiota can be found in the gut. The intestinal cell lining not only has to maintain a tightly regulated homeostasis during its high-throughput regeneration, but also a balanced relationship towards an extreme number of mutualistic or commensal inhabitants. Recent research suggests that advancing our understanding of the circumstances of such balanced and sometimes imbalanced interactions between gut microbiota and host AMPs should have therapeutic implications for different intestinal disorders.

Prophylactic antibiotics for endoscopy-associated peritonitis in peritoneal dialysis patients

INTRODUCTION

Continuous ambulatory peritoneal dialysis (CAPD) peritonitis may develop after endoscopic procedures, and the benefit of prophylactic antibiotics is unclear. In the present study, we investigated whether prophylactic antibiotics reduce the incidence of peritonitis in these patients.

PATIENTS AND METHODS

We retrospectively reviewed all endoscopic procedures, including esophagogastroduodenoscopy (EGD), colonoscopy, sigmoidoscopy, cystoscopy, hysteroscopy, and hysteroscopy-assisted intrauterine device (IUD) implantation/removal, performed in CAPD patients at Chang Gung Memorial Hospital, Taiwan, between February 2001 and February 2012.

RESULTS

Four hundred and thirty-three patients were enrolled, and 125 endoscopies were performed in 45 patients. Eight (6.4%) peritonitis episodes developed after the examination. Antibiotics were used in 26 procedures, and none of the patients had peritonitis (0% vs. 8.1% without antibiotic use; p=0.20). The peritonitis rate was significantly higher in the non-EGD group than in the EGD group (15.9% [7/44] vs. 1.2% [1/81]; p<0.005). Antibiotic use prior to non-EGD examinations significantly reduced the endoscopy-associated peritonitis rate compared to that without antibiotic use (0% [0/16] vs. 25% [7/28]; p<0.05). Peritonitis only occurred if invasive procedures were performed, such as biopsy, polypectomy, or IUD implantation, (noninvasive procedures, 0% [0/20] vs. invasive procedures, 30.4% [7/23]; p<0.05). No peritonitis was noted if antibiotics were used prior to examination with invasive procedures (0% [0/10] vs. 53.8% [7/13] without antibiotic use; p<0.05). Although not statistically significant, antibiotics may play a role in preventing gynecologic procedure-related peritonitis (antibiotics, 0% [0/4] vs. no antibiotics, 55.6% [5/9]; p=0.10).

CONCLUSION

Antibiotic prophylaxis significantly reduced endoscopy-associated PD peritonitis in the non-EGD group. Endoscopically assisted invasive procedures, such as biopsy, polypectomy, IUD implantation/removal, and dilatation and curettage (D&C), pose a high risk for peritonitis. Prophylactic antibiotics for peritonitis prevention may be required in colonoscopic procedures and gynecologic procedures.

Diagnosis and management of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) can result from failure of the gastric acid barrier, failure of small intestinal motility, anatomic alterations, or impairment of systemic and local immunity. The current accepted criteria for the diagnosis of SIBO is the presence of coliform bacteria isolated from the proximal jejunum with >10(5) colony-forming units/mL. A major concern with luminal aspiration is that it is only one random sampling of the small intestine and may not always be representative of the underlying microbiota. A new approach to examine the underlying microbiota uses rapid molecular sequencing, but its clinical utilization is still under active investigation. Clinical manifestations of SIBO are variable and include bloating, flatulence, abdominal distention, abdominal pain, and diarrhea. Severe cases may present with nutrition deficiencies due to malabsorption of micro- and macronutrients. The current management strategies for SIBO center on identifying and correcting underlying causes, addressing nutrition deficiencies, and judicious utilization of antibiotics to treat symptomatic SIBO.

In vivo assessment of growth and virulence gene expression during commensal and pathogenic lifestyles of luxABCDE-tagged Enterococcus faecalis strains in murine gastrointestinal and intravenous infection models

Cytolysin and gelatinase are prominent pathogenicity determinants associated with highly virulent Enterococcus faecalis strains. In an effort to explore the expression profiles of these virulence traits in vivo, we have employed E. faecalis variants expressing the luxABCDE cassette under the control of either the P16S, cytolysin, or gelatinase promoter for infections of Galleria mellonella caterpillars and mice. Systemic infection of G. mellonella with bioluminescence-tagged E. faecalis MMH594 revealed temporal regulation of both gelatinase and cytolysin promoters and demonstrated that these traits were induced in response to the host environment. Gavage of mice pretreated perorally with antibiotics resulted in efficient colonization of the murine gastrointestinal tract (GIT) in a strain-dependent manner, where the commensal baby isolate EF62 was more persistent than the nosocomial isolate MMH594. A highly significant correlation (R(2) > 0.94) was found between bioluminescence and the CFU counts in mouse fecal samples. Both strains showed similar preferences for growth and persistence in the ileum, cecum, and colon. Cytolysin expression was uniform in these compartments of the intestinal lumen. In spite of high numbers (10(9) CFU/g of intestinal matter) in the ileum, cecum, and colon, no evidence of translocation or systemic infection could be observed. In the murine intravenous infection model, cytolysin expression was readily detected in the liver, kidneys, and bladder. At 72 h postinfection, the highest bacterial loads were found in the liver, kidneys, and spleen, with organ-specific expression levels of cytolysin ~400- and ~900-fold higher in the spleen and heart, respectively, than in the liver and kidneys. Taken together, this system based on the bioluminescence imaging technology is established as a new, powerful method to monitor the differential regulation of E. faecalis virulence determinants and to study the spatiotemporal course of infection in living animals in real time.