Jejunal bacterial overgrowth and intestinal permeability in children with immunodeficiency syndromes

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.

Aetiology, diagnosis and management of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth is a small bowel disorder characterised by excessive amounts of bacteria populating the small intestine leading to symptoms of abdominal pain, bloating and change in bowel habit. This creates some degree of diagnostic uncertainty due to the overlap of these symptoms with numerous other gastrointestinal conditions. Quantitative culture of jejunal aspirates is the gold standard diagnostic test but has largely been replaced by glucose and lactulose breath tests due to their relative ease and accessibility. The approach to treatment centres around reducing bacterial numbers through antibiotic therapy and managing any predisposing factors. Further research is required in order to define the optimum antibiotic choice and duration of therapy as well as the potential diagnostic utility of home breath testing and capsule-based technology.

Asian-Pacific consensus on small intestinal bacterial overgrowth in gastrointestinal disorders: An initiative of the Indian Neurogastroenterology and Motility Association

In the clinical setting, small intestinal bacterial overgrowth (SIBO) is a frequent, but under-diagnosed entity. SIBO is linked to various gastrointestinal (GI) and non-GI disorders with potentially significant morbidity. The optimal management of SIBO is undefined while there is a lack of published consensus guidelines. Against this background, under the auspices of the Indian Neurogastroenterology and Motility Association (INMA), formerly known as the Indian Motility and Functional Diseases Association (IMFDA), experts from the Asian-Pacific region with extensive research and clinical experience in the field of gut dysbiosis including SIBO developed this evidence-based practice guideline for the management of SIBO utilizing a modified Delphi process based upon 37 consensus statements, involving an electronic voting process as well as face-to-face meetings and review of relevant supporting literature. These statements include 6 statements on definition and epidemiology; 11 on etiopathogenesis and pathophysiology; 5 on clinical manifestations, differential diagnosis, and predictors; and 15 on investigations and treatment. When the proportion of those who voted either to accept completely or with minor reservations was 80% or higher, the statement was regarded as accepted. The members of the consensus team consider that this guideline would be valuable to inform clinical practice, teaching, and research on SIBO in the Asian-Pacific region as well as in other countries.

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.

The longitudinal and cross-sectional heterogeneity of the intestinal microbiota

A central goal of microbiome research is to understand the factors that balance gut-associated microbial communities, thereby creating longitudinal and cross-sectional heterogeneity in their composition and density. Whereas the diet dictates taxa dominance, microbial communities are linked intimately to host physiology through digestive and absorptive functions that generate longitudinal heterogeneity in nutrient availability. Additionally, the host differentially controls the access to electron acceptors along the longitudinal axis of the intestine to drive the development of microbial communities that are dominated by facultatively anaerobic bacteria in the small intestine or obligately anaerobic bacteria in the large intestine. By secreting mucus and antimicrobials, the host further constructs microhabitats that generate cross-sectional heterogeneity in the colonic microbiota composition. Here we will review how understanding the host factors involved in generating longitudinal and cross-sectional microbiota heterogeneity helps define physiological states that are characteristic of or appropriate to a homeostatic microbiome.

Small Intestinal Bacterial Overgrowth

The term "small intestinal bacterial overgrowth" (SIBO) has been used to refer to a disorder resulting from the colonization of the small bowel by an increased number of microorganisms or by the presence of bacteria that are not usual constituents of this part of the gastrointestinal tract. Clinical presentations, often in patients with certain risk factors, can range from a full-blown malabsorption syndrome to such "functional" complaints as bloating and flatulence. SIBO is diagnosed by either culture of a small bowel aspirate or one of several breath tests. Treatment of SIBO entails risk factor modification, correction of nutritional deficiencies, and oral antibiotics.

Small intestinal bacterial overgrowth in spinal cord injury patients

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth is defined as the presence of excessive numbers of bacteria in the small bowel, causing gastrointestinal symptoms. This guideline statement evaluates criteria for diagnosis, defines the optimal methods for diagnostic testing, and summarizes treatment options for small intestinal bacterial overgrowth. This guideline provides an evidence-based evaluation of the literature through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process. In instances where the available evidence was not appropriate for a formal GRADE recommendation, key concepts were developed using expert consensus.

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.

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

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

The Structure and Function of the Human Small Intestinal Microbiota: Current Understanding and Future Directions

Despite growing literature characterizing the fecal microbiome and its association with health and disease, few studies have analyzed the microbiome of the small intestine. Here, we examine what is known about the human small intestinal microbiota in terms of community structure and functional properties. We examine temporal dynamics of select bacterial populations in the small intestine, and the effects of dietary carbohydrates and fats on shaping these populations. We then evaluate dysbiosis in the small intestine in several human disease models, including small intestinal bacterial overgrowth, short-bowel syndrome, pouchitis, environmental enteric dysfunction, and irritable bowel syndrome. What is clear is that the bacterial biology, and mechanisms of bacteria-induced pathophysiology, are enormously broad and elegant in the small intestine. Studying the small intestinal microbiota is challenged by rapidly fluctuating environmental conditions in these intestinal segments, as well as the complexity of sample collection and bioinformatic analysis. Because the functionality of the digestive tract is determined primarily by the small intestine, efforts must be made to better characterize this unique and important microbial ecosystem.

Risk Factors of Ambulatory Central Line-Associated Bloodstream Infection in Pediatric Short Bowel Syndrome

BACKGROUND

Children with short bowel syndrome (SBS) receiving home parenteral nutrition (HPN) are predisposed to ambulatory central line-associated bloodstream infection (A-CLABSI). Data describing risk factors of this infection in children are limited.

METHODS

Retrospective cohort, single-center, case-crossover study of children ≤18 years old with SBS receiving HPN from January 2012 to December 2016. Univariate and multivariate mixed effect Poisson regression identified the relative risk (RR) of A-CLABSI with proposed risk factors.

RESULTS

Thirty-five children were identified; median follow-up was 30 months. A-CLABSI rate was 4.2 per 1000 central line (CL) days. Univariate analysis identified younger age (RR: 0.92 per 12-month increase [95% confidence interval {CI}: 0.85-0.99; P = 0.036]), shorter small intestine length (RR: 0.96 per 10-cm increase [95% CI: 0.92-0.99; P = 0.008]), lower citrulline level (RR: 0.86 per 5-nmol/mL increase [95% CI: 0.75-0.99; P = 0.036]), and recent CL break (RR: 1.55 [95% CI: 1.06-2.28; P = 0.024]) as risk factors for A-CLABSI. Multivariate analysis showed increased A-CLABSI with clinical diagnosis of small intestine bacterial overgrowth (SIBO) (RR: 1.87 [95% CI: 1.1-3.17; P = 0.021]) and CL breaks (RR: 1.49 [95% CI: 1-2.22; P = 0.024]).

CONCLUSIONS

Factors influencing gut integrity increase A-CLABSI rate, supporting translocation as an important mechanism and target for prevention. Clinical diagnosis of SIBO increases A-CLABSI rate, but whether dysbiosis or diarrhea is responsible is an area for future research. CL maintenance is crucial, and prevention of breaks would likely decrease A-CLABSI rate.

Primary Immunodeficiency and the Gut

This article presents the most common gastrointestinal, hepatic, and pancreatic manifestations of the primary immunodeficiency diseases, including the appropriate laboratory testing, endoscopic evaluation, and recommendations for further management.

The inflammatory function of human IgA

The prevailing concept regarding the immunological function of immunoglobulin A (IgA) is that it binds to and neutralizes pathogens to prevent infection at mucosal sites of the body. However, recently, it has become clear that in humans IgA is also able to actively contribute to the initiation of inflammation, both at mucosal and non-mucosal sites. This additional function of IgA is initiated by the formation of immune complexes, which trigger Fc alpha Receptor I (FcαRI) to synergize with various other receptors to amplify inflammatory responses. Recent findings have demonstrated that co-stimulation of FcαRI strongly affects pro-inflammatory cytokine production by various myeloid cells, including different dendritic cell subsets, macrophages, monocytes, and Kupffer cells. FcαRI-induced inflammation plays a crucial role in orchestrating human host defense against pathogens, as well as the generation of tissue-specific immunity. In addition, FcαRI-induced inflammation is suggested to be involved in the pathogenesis of various chronic inflammatory disorders, including inflammatory bowel disease, celiac disease, and rheumatoid arthritis. Combined, IgA-induced inflammation may be used to either promote inflammatory responses, e.g. in the context of cancer therapy, but may also provide new therapeutic targets to counteract chronic inflammation in the context of various chronic inflammatory disorders.

Small Intestinal Bacterial Overgrowth: Nutritional Implications, Diagnosis, and Management

Small intestinal bacterial overgrowth (SIBO), characterized by the presence of excessive bacteria in the small intestine, is typically described as a malabsorptive syndrome occurring in the context of gut stasis syndromes. SIBO is now considered to be a disorder associated with diverse clinical conditions without classic risk factors for SIBO and a cause of several nonspecific gastrointestinal and nongastrointestinal symptoms. Because there is currently no gold standard for diagnosing SIBO, its prevalence and role in the pathogenesis of other diseases remain uncertain; as does optimal treatment of patients with relapsing symptoms.

Tissue macrophages as mediators of a healthy relationship with gut commensal microbiota

Mammals and microorganisms have evolved a complex and tightly controlled mutual relationship. This interaction grants protection and energy source for the microorganisms, and on the other hand, provides several immunologic, metabolic and physiological advantages for the host. The gastrointestinal tract (GI) harbors the largest bacteria diversity within the body and complex mechanisms control microbiota community under homeostasis. However, once disrupted, microbiota imbalance can lead to overt growth of resident and invasive populations, with potential risk for lethal diseases. In these cases, bacteria might also escape from the intestines and reach different organs through the blood and lymphatic circulation. To control these unwanted conditions, all body tissues are populated with resident macrophages that have the ability to capture and eliminate pathogens, avoiding their dissemination. Here we discuss the different routes for bacterial translocation from the intestinal tract, and how macrophages act in the removal of these microorganisms to prevent systemic infections and restore the homeostasis.

Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus

OBJECTIVES

Breath tests (BTs) are important for the diagnosis of carbohydrate maldigestion syndromes and small intestinal bacterial overgrowth (SIBO). However, standardization is lacking regarding indications for testing, test methodology and interpretation of results. A consensus meeting of experts was convened to develop guidelines for clinicians and research.

METHODS

Pre-meeting survey questions encompassing five domains; indications, preparation, performance, interpretation of results, and knowledge gaps, were sent to 17 clinician-scientists, and 10 attended a live meeting. Using an evidence-based approach, 28 statements were finalized and voted on anonymously by a working group of specialists.

RESULTS

Consensus was reached on 26 statements encompassing all five domains. Consensus doses for lactulose, glucose, fructose and lactose BT were 10, 75, 25 and 25 g, respectively. Glucose and lactulose BTs remain the least invasive alternatives to diagnose SIBO. BT is useful in the diagnosis of carbohydrate maldigestion, methane-associated constipation, and evaluation of bloating/gas but not in the assessment of oro-cecal transit. A rise in hydrogen of ≥20 p.p.m. by 90 min during glucose or lactulose BT for SIBO was considered positive. Methane levels ≥10 p.p.m. was considered methane-positive. SIBO should be excluded prior to BT for carbohydrate malabsorption to avoid false positives. A rise in hydrogen of ≥20 p.p.m. from baseline during BT was considered positive for maldigestion.

CONCLUSIONS

BT is a useful, inexpensive, simple and safe diagnostic test in the evaluation of common gastroenterology problems. These consensus statements should help to standardize the indications, preparation, performance and interpretation of BT in clinical practice and research.

Levothyroxine therapy and impaired clearance are the strongest contributors to small intestinal bacterial overgrowth: Results of a retrospective cohort study

AIM

To identify a set of contributors, and weight and rank them on a pathophysiological basis.

METHODS

Patients who have undergone a lactulose or glucose hydrogen breath test to rule out small intestinal bacterial overgrowth (SIBO) for various clinical symptoms, including diarrhoea, weight loss, abdominal pain, cramping or bloating, were seen as eligible for inclusion in a retrospective single-centre study. Clinical data such as co-morbidities, medication, laboratory parameters and other possible risk factors have been identified from the electronic data system. Cases lacking or with substantially incomplete clinical data were excluded from the analysis. Suspected contributors were summarised under four different pathophysiological pathways (impaired gastric acid barrier, impaired intestinal clearance, immunosuppression and miscellaneous factors including thyroid gland variables) and investigated using the χ² test, Student’s t-test and logistic regression models.

RESULTS

A total of 1809 patients who had undergone hydrogen breath testing were analysed. Impairment of the gastric acid barrier (gastrectomy, odds ratio: OR = 3.5, PPI therapy OR = 1.4), impairment of intestinal clearance (any resecting gastric surgery OR = 2.6, any colonic resection OR = 1.9, stenosis OR = 3.4, gastroparesis OR = 3.4, neuropathy 2.2), immunological factors (any drug-induced immunosuppression OR = 1.8), altered thyroid gland metabolism (hypothyroidism OR = 2.6, levothyroxine therapy OR = 3.0) and diabetes mellitus (OR = 1.9) were associated significantly to SIBO. Any abdominal surgery, ileocecal resection, vagotomy or IgA-deficiency did not have any influence, and a history of appendectomy decreased the risk of SIBO. Multivariate analysis revealed gastric surgery, stenoses, medical immunosuppression and levothyroxine to be the strongest predictors. Levothyroxine therapy was the strongest contributor in a simplified model (OR = 3.0).

CONCLUSION

The most important contributors for the development of SIBO in ascending order are immunosuppression, impairment of intestinal clearance and levothyroxine use, but they do not sufficiently explain its emergence.

Gastrointestinal Disorders Associated with Common Variable Immune Deficiency (CVID) and Chronic Granulomatous Disease (CGD)

Common variable immune deficiency (CVID) and chronic granulomatous disease (CGD) are two of the well-characterized primary immune deficiencies with distinct pathologic defects. While CVID is predominantly a disorder of the adaptive immune system, in CGD, innate immunity is impaired. In both syndromes, the clinical manifestations include an increased susceptibility to infections and a number of non-infectious, inflammatory conditions including systemic autoimmunity, as well as organ-specific pathology. Among the organ-associated disorders, gastrointestinal (GI) manifestations are one of the most intractable. As such, non-infectious inflammatory disorders of the GI tract are clinically challenging as they have protean manifestations, often resembling inflammatory bowel disease (IBD) or celiac disease, are notoriously difficult to treat, and hence are associated with significant morbidity and mortality. Therefore, assessing the pathogenesis and defining appropriate therapeutic approaches for GI disease in patients with CVID and CGD is imperative.

Small Bowel Bacterial Overgrowth in Children

OBJECTIVES

The aim of study was to perform a comprehensive review of the pathogenesis, available diagnostic procedures, prevalence, clinical manifestations, and consequences of small bowel bacterial overgrowth (SBBO) as well as treatment options in the pediatric population.

METHODS

A literature search including MEDLINE, PubMed, and Web of Science databases was performed.

RESULTS

SBBO is found in a variety of childhood conditions in which the normal homeostatic mechanisms restricting bacterial colonization in the small bowel are disturbed by congenital or acquired anatomical abnormalities, diminished gastric acid secretion, congenital alteration of intestinal motility or acquired small bowel diseases, or other chronic disorders including primary or acquired immunodeficiency. Data show that SBBO may be an underrecognized cause of pediatric morbidity. Although several diagnostic tests for SBBO determination are available, each has its drawbacks and limitations. Indeed, there is still no "criterion standard" for SBBO diagnosis in the pediatric population. Owing to lack of established guidelines and few published interventional studies that assess the effectiveness of SBBO therapy, treatment of children with SBBO remains empiric and comprises antibiotic or probiotic therapy.

CONCLUSIONS

Further research is needed to determine the clinical impact of SBBO and to establish diagnostic and therapeutic guidelines applicable to children.

Unbalanced Immune System: Immunodeficiencies and Autoimmunity

Increased risk of developing autoimmune manifestations has been identified in different primary immunodeficiencies (PIDs). In such conditions, autoimmunity and immune deficiency represent intertwined phenomena that reflect inadequate immune function. Autoimmunity in PIDs may be caused by different mechanisms, including defects of tolerance to self-antigens and persistent stimulation as a result of the inability to eradicate antigens. This general immune dysregulation leads to compensatory and exaggerated chronic inflammatory responses that lead to tissue damage and autoimmunity. Each PID may be characterized by distinct, peculiar autoimmune manifestations. Moreover, different pathogenetic mechanisms may underlie autoimmunity in PID. In this review, the main autoimmune manifestations observed in different PID, including humoral immunodeficiencies, combined immunodeficiencies, and syndromes with immunodeficiencies, are summarized. When possible, the pathogenetic mechanism underlying autoimmunity in a specific PID has been explained.

Human Immunodeficiency Virus-Associated Diarrhea: Still an Issue in the Era of Antiretroviral Therapy

Over half of patients with human immunodeficiency virus (HIV) experience diarrhea that contributes negatively to quality of life and adherence to antiretroviral therapy (ART). Opportunistic infectious agents that cause diarrhea in patients with HIV span the array of protozoa, fungi, viruses, and bacteria. With global use of ART, the incidence of diarrhea because of opportunistic infections has decreased; however, the incidence of noninfectious diarrhea has increased. The etiology of noninfectious diarrhea in patients with HIV is multifactorial and includes ART-associated diarrhea and gastrointestinal damage related to HIV infection (i.e., HIV enteropathy). A basic algorithm for the diagnosis of diarrhea in patients with HIV includes physical examination, a review of medical history, assessment of HIV viral load and CD4+ T cell count, stool microbiologic assessment, and endoscopic evaluation, if needed. For patients with negative diagnostic results, the diagnosis of noninfectious diarrhea may be considered. Pharmacologic options for the treatment of noninfectious diarrhea are primarily supportive; however, the use of many unapproved agents is based on unstudied and anecdotal information. In addition, these agents can be associated with treatment-limiting adverse events (AEs), such as drug-drug interactions with ART regimens, abuse liability, and additional gastrointestinal AEs. Currently, crofelemer, an antisecretory agent, is the only therapy approved in the USA for the symptomatic relief of noninfectious diarrhea in patients with HIV on ART.

Breath testing for small intestinal bacterial overgrowth: maximizing test accuracy

The diagnosis of small intestinal bacterial overgrowth (SIBO) has increased considerably owing to a growing recognition of its association with common bowel symptoms including chronic diarrhea, bloating, abdominal distention, and the irritable bowel syndrome. Ideally, an accurate and objective diagnosis of SIBO should be established before initiating antibiotic treatment. Unfortunately, no perfect test exists for the diagnosis of SIBO. The current gold standard, small-bowel aspiration and quantitative culture, is limited by its high cost, invasive nature, lack of standardization, sampling error, and need for dedicated infrastructure. Although not without shortcomings, hydrogen breath testing provides the simplest noninvasive and widely available diagnostic modality for suspected SIBO. Carbohydrates such as lactulose and glucose are the most widely used substrates in hydrogen breath testing, with glucose arguably providing greater testing accuracy. Lactose, fructose, and sorbitol should not be used as substrates in the assessment of suspected SIBO. The measurement of methane in addition to hydrogen can increase the sensitivity of breath testing for SIBO. Diagnostic accuracy of hydrogen breath testing in SIBO can be maximized by careful patient selection for testing, proper test preparation, and standardization of test performance as well as test interpretation.

Homeobox transcription factor VentX regulates differentiation and maturation of human dendritic cells

Dendritic cells (DCs) are specialized antigen presentation cells that play critical roles in the initiation and regulation of immune responses. The molecular determinants of DC differentiation and maturation are target of extensive investigation. VentX is a human homeobox transcriptional factor that regulates proliferation and differentiation of hematopoietic cells. In the current study, we report that ablation of VentX expression in monocytes significantly impaired their differentiation into DCs. Conversely, overexpression of VentX in monocytic THP1 cells accelerated their differentiation toward DCs. We showed that VentX regulates DC differentiation, in part, through modulating IL6 expression. Clinically, we found that VentX expression was elevated in intestinal lamina propria DCs (LPDCs) of inflamed mucosa from inflammatory bowel disease patients. Knockdown experiments suggested that VentX is essential for the maturation of LPDCs. In addition, corticosteroid treatment markedly decreased VentX expression in LPDCs and enforced expression of VentX counteracted the effects of corticosteroid on DCs maturation. Our data suggest that VentX is a critical transcriptional regulator of DC differentiation and maturation, and a potential target of immune regulation and therapy.

Review article: small intestinal bacterial overgrowth--prevalence, clinical features, current and developing diagnostic tests, and treatment

BACKGROUND

The symptoms and signs of small intestinal bacterial overgrowth (SIBO) are often identical to a variety of diseases and can lead to diagnostic confusion.

AIMS

To review the diagnostic options for SIBO and present new investigative options for the condition.

METHODS

A literature search was performed on MEDLINE, EMBASE and Web of Science for English articles and abstracts. Search terms included free text words and combinations of the following terms 'small intestinal bacterial overgrowth', 'small bowel bacterial overgrowth', 'diagnostic tests', 'treatment', 'antibiotics', 'probiotics', 'metabonomics', 'proton nuclear magnetic resonance spectroscopy', 'electronic nose' and 'field asymmetric ion mobility spectrometry'.

RESULTS

All of the available methods to test for SIBO have inherent limitations and no 'gold-standard' diagnostic test for the condition exists. Accurate diagnosis of SIBO requires identification of bacterial species growing inappropriately within the small intestine and symptom response to antibiotics. Proton nuclear magnetic resonance spectroscopy, electronic nose technology and/or field asymmetric ion mobility spectrometry may represent better investigative options for the condition.

CONCLUSIONS

Novel diagnostic options are needed to supplement or replace available tests.

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.

Potential mechanisms for the emerging link between obesity and increased intestinal permeability

Recently, increased attention has been paid to the link between gut microbial composition and obesity. Gut microbiota is a source of endotoxins whose increase in plasma is related to obesity and insulin resistance through increased intestinal permeability in animal models; however, this relationship still needs to be confirmed in humans. That intestinal permeability is subject to change and that it might be the interface between gut microbiota and endotoxins in the core of metabolic dysfunctions reinforce the need to understand the mechanisms involved in these aspects to direct more efficient therapeutic approaches. Therefore, in this review, we focus on the emerging link between obesity and increased intestinal permeability, including the possible factors that contribute to increased intestinal permeability in obese subjects. We address the concept of intestinal permeability, how it is measured, and the intestinal segments that may be affected. We then describe 3 factors that may have an influence on intestinal permeability in obesity: microbial dysbiosis, dietary pattern (high-fructose and high-fat diet), and nutritional deficiencies. Gaps in the current knowledge of the role of Toll-like receptors ligands to induce insulin resistance, the routes for lipopolysaccharide circulation, and the impact of altered intestinal microbiota in obesity, as well as the limitations of current permeability tests and other potential useful markers, are discussed. More studies are needed to reveal how changes occur in the microbiota. The factors such as changes in the dietary pattern and the improvement of nutritional deficiencies appear to influence intestinal permeability, and impact metabolism must be examined. Also, additional studies are necessary to better understand how probiotic supplements, prebiotics, and micronutrients can improve stress-induced gastrointestinal barrier dysfunction and the influence these factors have on host defense. Hence, the topics presented in this review may be beneficial in directing future studies that assess gut barrier function in obesity.

Chronic intestinal pseudo-obstruction due to lymphocytic intestinal leiomyositis: Case report and literature review

Lymphocytic intestinal leiomyositis is a rare entity, which causes chronic intestinal pseudo-obstruction (CIPO) in children. We present the first case of a boy who had pure red cell anemia 1 year before onset. Prolonged ileus developed after gastroenteritis and the patient was diagnosed using a biopsy of the intestinal wall. Findings from the present case indicate that there are three important factors for accurate diagnosis: history of enteritis, positive serum smooth muscle antibody, and lymphocyte infiltration with muscle destruction in the muscularis propria in the intestinal wall. Earlier diagnosis and induction of immunosuppressive therapy may be essential for a better outcome.

Chronic diarrhea and malabsorption due to hypogammaglobulinemia: a report on twelve patients

Hypogammaglobulinemic sprue (HGS), which may predispose to infection, is uncommon. Twelve patients (all men; median age 29 years, 15-50) with HGS (4%) of 296 with chronic small bowel diarrhea and malabsorption syndrome (MAS) during a 10-year period were analyzed. Treatment of HGS was delayed due to misdiagnosis as intestinal tuberculosis (n = 7) and diarrhea-predominant irritable bowel syndrome (n = 1). All had diarrhea and weight loss (median loss 12 Kg). Associated conditions were clubbing, bronchiectasis, and seizure (2 patients each), and hypothyroidism (n = 1). Laboratory parameters were urinary D-xylose median 0.46 g/5 g/5 h (range 0.2-1.6; normal ≥ 1), fecal fat 11.9 g/day (3.8-16.7; normal ≤ 7 g), serum IgA, IgG, and IgM: 23.5 mg/dL (17-114; normal 90-450), 584 mg/dL (145-1051; normal 800-1800), and 23 (0-40.3; normal 60-280). IgA, IgG, and IgM were low in 10, 10, and 11, respectively. Duodenal biopsy was normal in 6 patients and showed partial villous atrophy in 6 and nodular lymphoid hyperplasia in two. Associated infections were giardiasis (n = 1), disseminated strongyloidiasis (1), small intestinal bacterial overgrowth (3), septicemia (2), and septic arthritis (1). Two patients died of sepsis, five are well on immunoglobulin and specific anti-infective treatment, and five are lost to follow up. Approximately 4% patients with MAS have hypogammaglobulinemia, which is often associated with infection and is diagnosed late.

Small intestinal bacterial overgrowth syndrome

Human intestinal microbiota create a complex polymicrobial ecology. This is characterised by its high population density, wide diversity and complexity of interaction. Any dysbalance of this complex intestinal microbiome, both qualitative and quantitative, might have serious health consequence for a macro-organism, including small intestinal bacterial overgrowth syndrome (SIBO). SIBO is defined as an increase in the number and/or alteration in the type of bacteria in the upper gastrointestinal tract. There are several endogenous defence mechanisms for preventing bacterial overgrowth: gastric acid secretion, intestinal motility, intact ileo-caecal valve, immunoglobulins within intestinal secretion and bacteriostatic properties of pancreatic and biliary secretion. Aetiology of SIBO is usually complex, associated with disorders of protective antibacterial mechanisms (e.g. achlorhydria, pancreatic exocrine insufficiency, immunodeficiency syndromes), anatomical abnormalities (e.g. small intestinal obstruction, diverticula, fistulae, surgical blind loop, previous ileo-caecal resections) and/or motility disorders (e.g. scleroderma, autonomic neuropathy in diabetes mellitus, post-radiation enteropathy, small intestinal pseudo-obstruction). In some patients more than one factor may be involved. Symptoms related to SIBO are bloating, diarrhoea, malabsorption, weight loss and malnutrition. The gold standard for diagnosing SIBO is still microbial investigation of jejunal aspirates. Non-invasive hydrogen and methane breath tests are most commonly used for the diagnosis of SIBO using glucose or lactulose. Therapy for SIBO must be complex, addressing all causes, symptoms and complications, and fully individualised. It should include treatment of the underlying disease, nutritional support and cyclical gastro-intestinal selective antibiotics. Prognosis is usually serious, determined mostly by the underlying disease that led to SIBO.

A systematic review of diagnostic tests for small intestinal bacterial overgrowth

BACKGROUND

A growing number of studies seem to suggest that small intestinal bacterial overgrowth (SIBO) is a common clinical problem. Although various techniques are available to make this diagnosis, tradition has accepted small bowel aspirate (>10(5) cfu/ml) as a gold standard. In this systematic review, the validity of culture and other diagnostic testing for SIBO is evaluated.

METHODS

We performed a systematic review of the literature from 1966 to present using electronic databases (PubMed and OVID). Full paper review of those abstracts that fulfilled preset criteria was carried out to evaluate the validity of various tests in diagnosing SIBO. Finally, all papers were evaluated against published standards for studies on diagnostic testing.

RESULTS

Seventy-one papers met the criteria for detailed review. Studies were very heterogeneous with regards to patient populations, test definitions, sample size, and methods in general. Small bowel colony counts appeared elevated in most gastrointestinal diseases compared to controls. The traditional definition of >10(5) cfu/ml was usually indicative of stagnant loop conditions. Although, numerous diagnostic tests were studied, not even culture papers met the quality standards described by Reid et al. Breath testing and other diagnostic testing suffered therefore from the lack of a gold standard against which to validate in addition to the poor quality.

CONCLUSIONS

There is no validated diagnostic test or gold standard for SIBO. In this context, the most practical method to evaluate SIBO in studies at this time would be a test, treat, and outcome technique.

A liquid chromatography/mass spectrometry method for the evaluation of intestinal permeability

OBJECTIVES

Lactulose to mannitol ratio (L/M) in urine is used as a non invasive assay to measure intestinal permeability. We describe here a rapid, specific and sensitive LC-MS/MS method for the measurement of these compounds in urine of children affected by abdominal recurrent pain (ARP).

DESIGN AND METHODS

The study has been performed on 50 children from the Pediatric Unit. The chromatographic separation was accomplished by using an NH(2)-column, the detection with a Q-Trap 2000 system.

RESULTS

Multiple calibration curve exhibited consistent linearity and reproducibility. Linear responses were observed in the concentration range 0-400 microg/mL for both mannitol and lactulose. Limits of detection were 12.5 mg/L for lactulose and 1.25 mg/L for mannitol with a signal-to-noise ratio of 10.

CONCLUSIONS

The comparison of L/M values of healthy children with those found in children affected by idiopathic ARP demonstrates that in the latter subjects an alteration of intestinal permeability occurs. The method can represent a useful tool to monitor the intestinal functionality in children with ARP conditions and help for an accurate patient discrimination for diet restrictions.

Risk factors for small bowel bacterial overgrowth in cystic fibrosis

OBJECTIVES

The purpose of this study was to determine the prevalence of small bowel bacterial overgrowth in patients with pancreatic-insufficient cystic fibrosis (CF) compared with age-matched controls and to identify potential risk factors for small bowel bacterial overgrowth.

PATIENTS AND METHODS

Fifty patients, 25 pancreatic-insufficient CF study patients (mean age, 17 y) and 25 gastrointestinal clinic control patients (mean age, 15 y), completed a glucose-hydrogen breath test after an overnight fast. Study patients completed a quality-of-life questionnaire modified from the Cystic Fibrosis Questionnaire. The medical history of each patient was compared with breath test results. A positive breath test was defined as a fasting hydrogen > or =15 ppm or a rise of > or =10 ppm hydrogen over baseline during the test.

RESULTS

The prevalence of positive breath tests was higher in the CF study group (56%) than in the control group (20%) (P = 0.02). The mean fasting hydrogen levels of patients in the study and control groups were 22 and 5 ppm (P = 0.0001). The mean questionnaire scores were not significantly different between breath test-positive and -negative study patients. The use of azithromycin was associated with an increased risk of a positive breath test. Use of laxatives and inhaled ipratropium was associated with a decreased risk of a positive breath test.

CONCLUSIONS

Patients with CF were more likely to have elevated fasting hydrogen levels compared with controls. This suggests a high prevalence of small bowel bacterial overgrowth in CF patients. Medications commonly used by CF patients may influence intestinal health.

Small intestinal bacterial overgrowth: a comprehensive review

Small intestinal bacterial overgrowth (SIBO), defined as excessive bacteria in the small intestine, remains a poorly understood disease. Initially thought to occur in only a small number of patients, it is now apparent that this disorder is more prevalent than previously thought. Patients with SIBO vary in presentation, from being only mildly symptomatic to suffering from chronic diarrhea, weight loss, and malabsorption. A number of diagnostic tests are currently available, although the optimal treatment regimen remains elusive. Recently there has been renewed interest in SIBO and its putative association with irritable bowel syndrome. In this comprehensive review, we will discuss the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of SIBO.

Lactulose and mannitol intestinal permeability detected by capillary electrophoresis

Aim of this study was to set up a method by capillary electrophoresis to detect lactulose and mannitol in urine after an oral load, and to estimate the intestinal permeability in controls and in type I diabetes patients. The underivatized carbohydrates were monitored by indirect UV detection using sorbate, cetyltrimethylammonium bromide and LiOH as background electrolyte. Urines were purified by solid phase extraction, shaken with cation exchange resin, filtered and analysed. Carbohydrates migrated in <10 min in relation to their pK(a) and M(r). Controls (n = 33) and patients (n = 23) had an excretion ratio lactulose/mannitol 0.025 (0.018-0.051) and 0.067 (0.050-0.127), respectively (p < 0.01, median, interquartile range).

The pathogenesis of gastrointestinal bacterial overgrowth

The normal indigenous intestinal microflora consists of about 10(15) bacteria that under physiological conditions reside mainly in the lower gastrointestinal tract. Bacterial overgrowth implies abnormal bacterial colonization of the upper gut, resulting from failure of specific defense mechanisms restricting colonization under physiological conditions. At present two types of bacterial overgrowth with defined pathogenesis can be distinguished: (1) gastric overgrowth with upper respiratory tract microflora resulting from selective failure of the gastric acid barrier, and (2) gastrointestinal overgrowth with Gram-negative bacilli (enteric bacteria) resulting from failure of intestinal clearance. Helicobacter pylori-induced gastritis of the oxyntic mucosa is the main cause of acquired failure of the gastric acid barrier, which is common among the healthy elderly. Intestinal clearance may fail as the result of impaired intestinal peristalsis or anatomical abnormalities that alter luminal flow. Impaired peristalsis is associated with conditions interfering with intestinal neuromuscular function including myopathic, neuropathic, autoimmune, infectious, inflammatory, metabolic, endocrine, and neoplastic diseases. Anatomical abnormalities are mainly the result of gastrointestinal surgery, intestinal diverticula or fistula. Combined failure of intestinal clearance and the gastric acid barrier results in more severe colonization with Gram-negative bacilli. Gram-negative bacilli are uncommon in the upper gut of otherwise healthy individuals with gastric hypochlorhydria, being acquired (H. pylori) or drug-induced. Significant bacterial overgrowth with Gram-negative bacilli is a rational in the search for an explanation to optimize clinical management. The clinical significance of colonization with upper respiratory tract microflora remains unclear. Translocation of live bacteria, their metabolic products, or antigens from a small bowel colonized by Gram-negative bacilli play a role in the pathogenesis of spontaneous bacterial peritonitis in hepatic disease and in certain types of sepsis, indicating that further studies can point to new patient populations with potential benefit from medical treatment.

Role of passive and adaptive immunity in influencing enterocyte-specific gene expression

Numerous genes expressed by intestinal epithelial cells are developmentally regulated, and the influence that adaptive (AI) and passive (PI) immunity have in controlling their expression has not been evaluated. In this study, we tested the hypothesis that both PI and AI influenced enterocyte gene expression by developing a breeding scheme that used T and B cell-deficient recombination-activating gene (RAG) mice. RNA was isolated from the liver and proximal/distal small intestine at various ages, and the steady-state levels of six different transcripts were evaluated by RNase protection assay. In wild-type (WT) pups, all transcripts [Fc receptor of the neonate (FcRn), polymeric IgA receptor (pIgR), GLUT5, lactase-phlorizin hydrolase (lactase), apical sodium-dependent bile acid transporter (ASBT), and Na+/glucose cotransporter (SGLT1)] studied were developmentally regulated at the time of weaning, and all transcripts except ASBT had the highest levels of expression in the proximal small intestine. In WT suckling pups reared in the absence of PI, pIgR mRNA levels were increased 100% during the early phase of development. In mice lacking AI, the expression of pIgR and lactase were significantly attenuated, whereas FcRn and GLUT5 levels were higher compared with WT mice. Finally, in the absence of both passive and active immunity, expression levels of pIgR and lactase were significantly lower than similarly aged WT mice. In summary, we report that the adaptive and passive immune status of mice influences steady-state mRNA levels of several important, developmentally regulated enterocyte genes during the suckling and weaning periods of life.

Gastrointestinal disorders of the critically ill. Bacterial translocation in the gut

The human gastrointestinal tract is colonized by a dense population of microorganisms, referred to as the bacterial flora. Although the gut provides a functional barrier between these organisms and the host, bacterial translocation is a common event in the healthy person. However, in critically ill patients, with various underlying diseases, this bacterial translocation may lead to infections and consequently to a further reduction in general health status. The mechanism of bacterial translocation is widely, and somehow controversially investigated in vitro and in animal models. In human studies, several diseases have been associated with bacterial translocation. However, methodological shortcomings, insufficient populations and conflicting results leave many open questions. This is also reflected in the various published therapeutic strategies. To overcome this problem more investigations in humans are needed, especially in techniques for detecting bacterial translocation.

Effect of chronic administration of tacrolimus and cyclosporine on human gastrointestinal permeability

The antirejection drug tacrolimus (FK506) has been reported to impair intestinal permeability in an early stage after orthotopic liver transplantation (OLT), and cyclosporine (CsA) has shown a similar effect in animals. We studied the chronic effect of FK506 and CsA on gastroduodenal and intestinal permeability and on blood endotoxin levels in patients 2 to 3 years after OLT. Thirty-two OLT patients (22 men and 10 women; mean age, 44.8 +/- 7.1) who had received CsA (n = 19) or FK506 (n = 13) and 10 healthy volunteers (6 male and 4 female, mean age 41.7 +/- 5.4) were assessed for gastroduodenal permeability by recovery in urine of sucrose after oral administration and for intestinal permeability by recovery in urine after oral loads of rhamnose and lactulose, which evaluate the intracellular and paracellular routes, respectively. In all subjects, plasma levels of endotoxins also were assessed. Gastroduodenal permeability was similar in patients and controls (0.03 +/- 0.003 versus 0.04 +/- 0.01%, P = NS). In regard to intestinal permeability, passage through the intracellular route was significantly reduced in OLT patients compared with controls (1.13 +/- 0.06 versus 2.74 +/- 0.17%, P <.01), but paracellular permeability was unchanged (0.14 +/- 0.007 versus 0.13 +/- 0.01%, P = NS). Serum endotoxin levels were similar in all subjects. We conclude that chronic administration of FK506 or CsA induces a clinically irrelevant, selective dysfunction of monosaccharide absorption, but does not affect gastroduodenal or intestinal permeability.

Lower frequency of MMC is found in IBS subjects with abnormal lactulose breath test, suggesting bacterial overgrowth

We have recently described an association between irritable bowel syndrome (IBS) and abnormal lactulose breath test, suggesting small intestinal bacterial overgrowth (SIBO). However, the mechanism by which SIBO develops in IBS is unknown. In this case-control study we evaluate the role of small intestinal motility in subjects with IBS and SIBO. Small intestinal motility was studied in consecutive IBS subjects with SIBO on lactulose breath test. After fluoroscopic placement of an eight-channel water-perfused manometry catheter, 4-hr fasting recordings were obtained. Based on this, the number and duration of phase III was compared to 30 control subjects. To test whether there was a relationship between the motility abnormalities seen and the SIBO status of the patient at the time of the motility, subjects with a breath test within 5 days of the antroduodenal manometry were also compared. Sixty-eight subjects with IBS and SIBO were compared to controls. The number of phase III events was 0.7 +/- 0.8 in IBS subjects and 2.2 +/- 1.0 in controls (P < 0.000001). The duration of phase III was 305 +/- 123 sec in IBS subjects and 428 +/- 173 in controls (P < 0.001). Subjects whose SIBO was still present at the time of manometry had less frequent phase III events than subjects with eradicated overgrowth (P < 0.05). In conclusion, phase III is reduced in subjects with IBS and SIBO. Eradication of bacterial overgrowth seems to result in some normalization of motility.

Use of an orally administered combined sugar solution to evaluate intestinal absorption and permeability in cats

OBJECTIVE

To evaluate intestinal permeability and absorption in healthy cats in association with diet and normal intestinal microflora.

ANIMALS

6 healthy domestic shorthair cats.

PROCEDURE

A sugar solution containing D-xylose, 30-methyl-D-glucose, L-rhamnose, lactulose, and 51Cr-EDTA was administered intragastrically to healthy cats, and urinary excretion of ingested sugars was determined 5 hours after administration. After the same cats had received metronidazole for 1 month, the study was repeated. A final study was performed while cats were maintained on a new diet differing in composition and processing.

RESULTS

Lactulose-to-rhamnose ratios, reflecting intestinal permeability, were higher in cats, compared with values for humans or dogs, and values obtained before and after metronidazole administration (mean +/- SEM; before, 0.40 +/- 0.08; after, 0.45 +/- 0.09) were not significantly different. Intestinal absorption also was unaltered after antibiotic administration, and the xylose-to-glucose ratio was 0.70 +/- 0.03 before and 0.71 +/- 0.06 after metronidazole administration. Sugar recovery did not differ significantly while cats were maintained on canned or dry food.

CONCLUSIONS AND CLINICAL RELEVANCE

Reference ranges were established for the percentage urinary recovery of orally administered D-xylose, 3-0-methyl-D-glucose, L-rhamnose, lactulose, and 51Cr-EDTA obtained after 5 hours in healthy cats. The intestines of cats appear to be more permeable than those of other species, although the normal bacterial microflora does not appear to influence the integrity or function of the feline intestine, because values obtained for the measured variables before or after antibiotic administration were not significantly different. In addition, differences were not detected when the diet was completely altered.

Intestinal permeability of x-ray constrast media iodixanol and iohexol during bacterial overgrowth of small intestines in rats

To investigate the recovery of iodinated water-soluble contrast medium from small bowel with small morphological alterations, iohexol or iodixanol was instilled through an orogastric tube in rats 14 days after surgery that established a self-filling blind loop in the jejunum. This rat model induced small bowel bacterial overgrowth with only minor abnormalities observed on histology and scanning electron microscopy. Animals with end-to-end anastomosis of the jejunum or unoperated rats served as controls. Compared with unoperated animals, urinary recovery of iohexol and iodixanol was significantly higher in both groups that underwent surgery. Moreover, the contrast medium recovery was numerically higher in the self-filling blind loop group given iodixanol than in the end-to-end anastomosis group, although not statistically significant, P = 0.09. Our results indicate that iohexol and iodixanol may detect small barrier impairments in the intestines. Iodixanol, the largest of the two, may seem to differentiate better between normal and minimally impaired intestinal barrier.

Teste do H2 no ar expirado na avaliação de absorção de lactose e sobrecrescimento bacteriano no intestino delgado de escolares

Estudos realizados há mais de 10 anos demonstraram que a deficiência ontogenética de lactase é freqüente na população brasileira. Entretanto, esses estudos se basearam no incremento da glicemia após sobrecarga de doses não utilizadas habitualmente na dieta. Atualmente, aceita-se que a avaliação da absorção da lactose com o teste do hidrogênio no ar expirado é mais apropriada que o teste da curva glicêmica. Por outro lado, a enteropatia ambiental sintomática e/ou assintomática constituem um grave problema de saúde pública em grupos populacionais de baixo nível sócio-econômico de nosso meio. A ocorrência de sobrecrescimento bacteriano no intestino delgado de crianças com enteropatia ambiental, foi caracterizada em crianças moradoras em favelas. Sobrecrescimento bacteriano no intestino delgado é caracterizado pela presença de bactérias pertencentes à flora colônica no intestino delgado. Objetivando avaliar a freqüência de má absorção de lactose e determinar a ocorrência de sobrecrescimento bacteriano no intestino delgado em crianças escolares, através do teste do H2 no ar expirado, investigaram-se 83 alunos de uma escola localizada na região periférica da cidade de Marília, Estado de São Paulo, após sobrecarga oral de lactose e lactulose. Foram colhidas também amostras de fezes para pesquisa de parasitas. Má absorção de lactose foi observada em 19 (22,9%) escolares e intolerância à lactose em 10 (12,0%). Sobrecrescimento bacteriano no intestino delgado foi identificado pelo teste do H2 no ar expirado em 6 (7,2%) dos 83 escolares. Giardia lamblia foi o parasita mais freqüentemente isolado nas fezes dos escolares. A ocorrência de deficiência ontogenética de lactase observada neste grupo de crianças foi semelhante ao relatado para populações caucasianas. Sobrecrescimento bacteriano foi encontrado neste grupo de crianças assintomáticas, podendo refletir as condições desfavoráveis de seu meio ambiente.

Antibiotic efficacy in small intestinal bacterial overgrowth-related chronic diarrhea: a crossover, randomized trial

BACKGROUND & AIMS

No controlled trial has examined the clinical efficacy of antibiotics in small bowel bacterial overgrowth.

METHODS

Ten patients with bacterial overgrowth-related diarrhea underwent the following five 7-day treatment periods: untreated (control period), then placebo, and subsequently, in random order and blinded fashion, norfloxacin (800 mg/day), amoxicillin-clavulanic acid (1500 mg/day), and Saccharomyces boulardii (1500 mg/day). A hydrogen breath test was performed on the first and last day of each period.

RESULTS

Daily stool frequency was similar during the control and placebo periods (4.2 +/- 0.6 vs. 3.9 +/- 0.6 [mean +/- SEM], respectively). Norfloxacin and amoxicillin-clavulanic acid led to a significant reduction in daily stool frequency (2.3 +/- 0.4 and 3.0 +/- 0.5, respectively; P < 0.01 vs. placebo period) after 2.0 +/- 1.4 and 1.2 +/- 0.4 days, which was maintained for 6.1 +/- 3.7 and 6.0 +/- 9.6 days, respectively. Breath-expired H(2) volume decreased with norfloxacin (37 +/- 8 to 12 +/- 5 mL per 2 hours; P < 0.01) and amoxicillin-clavulanic acid (24 +/- 6 to 8 +/- 4 mL per 2 hours, respectively; P = 0.01), but H(2) breath test result was negative in only 3 and 5 patients.

CONCLUSIONS

Norfloxacin and amoxicillin-clavulanic acid are effective in the treatment of bacterial overgrowth-related diarrhea.