Post-infectious irritable bowel syndrome

Irritable bowel syndrome and inflammatory bowel disease overlap syndrome: pieces of the puzzle are falling into place

Irritable bowel syndrome (IBS), a common gastrointestinal disorder involving the gut-brain axis, and inflammatory bowel disease (IBD), a chronic relapsing inflammatory disorder, are both increasing in incidence and prevalence in Asia. Both have significant overlap in terms of symptoms, pathophysiology, and treatment, suggesting the possibility of IBS and IBD being a single disease entity albeit at opposite ends of the spectrum. We examined the similarities and differences in IBS and IBD, and offer new thoughts and approaches to the disease paradigm.

Non-enteric infections, antibiotic use, and risk of development of functional gastrointestinal disorders

BACKGROUND

Gastrointestinal infections are risk factors for irritable bowel syndrome (IBS) and functional dyspepsia (FD). We investigated whether non-enteric infections and antibiotic exposure are also associated with the development of functional gastrointestinal disorders (FGIDs).

METHODS

In a nested case-control study, random samples of Olmsted County, MN, were mailed valid self-report questionnaires from 1988 through 1994, and then follow-up questionnaires from 1995 through 2003. Survey responders who did not report any FGID symptoms at baseline, but then reported such symptoms in at least one subsequent survey, were classified as new-onset cases. Age-matched controls were individuals who did not have symptoms at either the initial or subsequent surveys.

KEY RESULTS

The overall response rate was 78% to the initial survey and 52% to the follow-up survey. Based on the responses, 316 participants had a new onset of an FGID (43 IBS constipation, 95 IBS diarrhea, 25 IBS mixed, and 153 other FGIDs, including FD) and 250 did not (controls). Around 76% (241/316) of cases reported a non-enteric infection vs 66% (166/250) of the controls. The frequency of enteric infections was similar between the two groups. Of the new FGID cases, 83% had a non-enteric infection that was treated with antibiotic. In a logistic regression model, treatment with antibiotics for a non-gastrointestinal infection was associated with the development of an FGID (odds ratio = 1.90; 95% CI: 1.21-2.98; p = 0.005), after adjusting for age and sex.

CONCLUSIONS & INFERENCES

Based on a case-control study, treatment of a non-gastrointestinal infection with antibiotics appears to be a risk factor for development of an FGID.

Food allergy in irritable bowel syndrome: The case of non-celiac wheat sensitivity

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, having a prevalence of 12%-30% in the general population. Most patients with IBS attribute their symptoms to adverse food reactions. We review the role of diet in the pathogenesis of IBS and the importance of dietary factors in the management of these patients. The MEDLINE electronic database (1966 to Jan 2015) was searched using the following keywords: "food", "diet", "food allergy", "food hypersensitivity", "food intolerance", "IBS", "epidemiology", "pathogenesis", "pathophysiology", "diagnosis", "treatment". We found 153 eligible papers; 80 were excluded because: not written in English, exclusive biochemical and experimental research, case reports, reviews, and research otherwise not relevant to our specific interest. We selected 73 papers: 43 original papers, 26 reviews and 4 letters to the editor. These papers focused on IBS pathogenesis, the association between IBS and atopy, and between IBS and food allergy, the relationship between IBS and non-celiac wheat sensitivity, the role of diet in IBS. Pending further scientific evidence, a cautious approach is advisable but the concept of food allergy should be included as a possible cause of IBS, and a dietary approach may have a place in the routine clinical management of IBS.

Pathogenesis of irritable bowel syndrome--review regarding associated infection and immune activation

There is increasing evidence regarding the role of immune activation in the etiology of irritable bowel syndrome (IBS), which has been mainly been shown in studies investigating mechanisms of postinfectious IBS (PI-IBS). Exposure to intestinal infection induces persistent low-grade systemic and mucosal inflammation, which is characterized by an altered population of circulating cells, mucosal infiltration of immune cells and increased production of various cytokines in IBS patients. Recent studies have also indicated an increased innate immune response in these patients by evaluating expression and activation of Toll-like receptors (TLRs). These findings suggest that immune activation may play a crucial role in the pathogenesis of IBS. In addition, psychological stress has been reported to be one of the factors that induces immune activation. However, it remains unknown whether immune activation in IBS patients is largely dependent on infectious gastroenteritis and/or psychological stress. Additional studies are necessary to understand the precise mechanism of immune activation and its relationship to the development of IBS.

Irritable bowel syndrome and gastrointestinal parasite infection in a developing nation environment

Postinfectious IBS is defined in the industrialized world as IBS onset following a sentinel gastrointestinal infection. In developing nations, where repeated bacterial and parasitic gastrointestinal infections are common, the IBS pathophysiology may be altered. Our aim was to investigate the relationship between intestinal parasite infection and IBS in the “nonsterile” developing world environment. IBS subjects were identified from a population-based sample of 1624 participants using the Rome II Modular Questionnaire. Stool samples from cases and randomly selected controls were examined for ova and parasites. Logistic regression models explored the relationship between IBS and parasite infection. The overall IBS prevalence among participants was 13.2% (9.3% males, 15.9% females). There was no difference in parasite carriage between IBS cases and controls, 16.6% versus 15.4% (P = 0.78), nor among IBS subtypes. The pathophysiology of post-infectious IBS may be altered in the developing world as compared to industrialized nations and warrants investigation.

Perceived food hypersensitivity: a review of 10 years of interdisciplinary research at a reference center

Perceived food hypersensitivity is a prevalent, but poorly understood condition. In this review article, we summarize narratively recent literature including results of our 10 years' interdisciplinary research program dealing with such patients. The patients (more than 400) included in our studies were all adults referred to a university hospital because of gastrointestinal complaints self-attributed to food hypersensitivity. Despite extensive examinations, food allergy was seldom diagnosed. The majority of the patients fulfilled the diagnostic criteria for irritable bowel syndrome. In addition, most suffered from several extra-intestinal health complaints and had considerably impaired quality of life. However, psychological factors could explain only approximately 10% of the variance in the patients' symptom severity and 90% of the variance thus remained unexplained. Intolerance to low-digestible carbohydrates was a common problem and abdominal symptoms were replicated by carbohydrate ingestion. A considerable number of patients showed evidence of immune activation by analyses of B-cell activating factor, dendritic cells and "IgE-armed" mast cells. Multiple factors such as immune activation, disturbed intestinal fermentation, enteric dysmotility, post-infectious changes and "local" allergy in the gut as well as psychological disturbances may play a role in the pathophysiology of perceived food hypersensitivity. Hence, our results support the view that management of these patients should be interdisciplinary.

Irritable bowel syndrome, gut microbiota and probiotics

Irritable bowel syndrome (IBS) is a complex disorder characterized by abdominal symptoms including chronic abdominal pain or discomfort and altered bowel habits. The etiology of IBS is multifactorial, as abnormal gut motility, visceral hypersensitivity, disturbed neural function of the brain-gut axis and an abnormal autonomic nervous system are all implicated in disease progression. Based on recent experimental and clinical studies, it has been suggested that additional etiological factors including low-grade inflammation, altered gut microbiota and alteration in the gut immune system play important roles in the pathogenesis of IBS. Therefore, therapeutic restoration of altered intestinal microbiota may be an ideal treatment for IBS. Probiotics are live organisms that are believed to cause no harm and result in health benefits for the host. Clinical efficacy of probiotics has been shown in the treatment or prevention of some gastrointestinal inflammation-associated disorders including traveler's diarrhea, antibiotics-associated diarrhea, pouchitis of the restorative ileal pouch and necrotizing enterocolitis. The molecular mechanisms, as cause of IBS pathogenesis, affected by altered gut microbiota and gut inflammation-immunity are reviewed. The effect of probiotics on the gut inflammation-immune systems and the results from clinical trials of probiotics for the treatment of IBS are also summarized.

Trauma history and risk of the irritable bowel syndrome in women veterans

BACKGROUND

Over 1.8 million women in the U.S. are veterans of the armed services. They are at increased risk of occupational traumas, including military sexual trauma.

AIM

To evaluate the association between major traumas and irritable bowel syndrome among women veterans accessing Veteran Affairs (VA) healthcare.

METHODS

We administered questionnaires to assess trauma history as well as IBS, post-traumatic stress disorder (PTSD) and depression symptoms to 337 women veterans seen for primary care at VA Women's Clinic between 2006 and 2007. Logistic regression was used to evaluate the association between individual traumas and IBS risk after adjustment for age, ethnicity, PTSD and depression.

RESULTS

Irritable bowel syndrome prevalence was 33.5%. The most frequently reported trauma was sexual assault (38.9%). Seventeen of eighteen traumas were associated with increased IBS risk after adjusting for age, ethnicity, PTSD and depression, with six statistically significant [range of adjusted odds ratios (OR) between 1.85 (95% CI, 1.08-3.16) and 2.6 (95% CI, 1.28-3.67)]. Depression and PTSD were significantly more common in IBS cases than controls, but neither substantially explained the association between trauma and increased IBS risk.

CONCLUSIONS

Women veterans report high frequency of physical and sexual traumas. A lifetime history of a broad range of traumas is independently associated with an elevated risk of the irritable bowel syndrome.

Irritable bowel syndrome and inflammatory bowel disease: infectious gastroenteritis-related disorders?

Infectious gastroenteritis may be one of the important factors in the development of irritable bowel syndrome (IBS), with affected individuals often categorized as having post-infectious IBS (PI-IBS), and is linked to the onset of symptoms in approximately 10-20% of patients diagnosed with IBS. Intestinal mucosal infiltration of T cells and mast cells, and enterochromaffin cell hyperplasia are significant immunological and pathological findings that reveal the pathogenesis of PI-IBS, and results of laboratory studies using animal models of PI-IBS clearly support clinical evidence. Recently, infectious gastroenteritis has also been suggested to be associated with the development of inflammatory bowel disease (IBD), and various studies have suggested that individuals with IBS or IBS-like symptoms may be susceptible to initiation of IBD. However, it is still unclear whether infectious gastroenteritis is directly or indirectly (through PI-IBS) linked to the initiation of IBD. Additional studies are necessary to understand the clinical overlap among infectious gastroenteritis, IBS, and IBD.

A rat model of chronic postinflammatory visceral pain induced by deoxycholic acid

BACKGROUND & AIMS

Chronic visceral hyperalgesia is considered an important pathophysiologic symptom in irritable bowel syndrome (IBS); previous gastrointestinal inflammation is a potent etiologic factor for developing IBS. Although there are several animal models of adult visceral hypersensitivity after neonatal perturbation or acute colonic irritation/inflammation, current models of postinflammatory chronic visceral hyperalgesia are unsatisfactory. The aim of this study was to establish a model of chronic visceral hyperalgesia after colonic inflammation in the rat.

METHODS

Deoxycholic acid (DCA) was instilled into the rat colon daily for 3 days and animals were tested for up to 4 weeks.

RESULTS

DCA induced mild, transient colonic inflammation within 3 days that resolved within 3 weeks. An exaggerated visceromotor response, referred pain to mechanical stimulation, increased spinal Fos expression, and colonic afferent and dorsal horn neuron activity were apparent by 1 week and persisted for at least 4 weeks, indicating chronic dorsal horn hyperexcitability and visceral hyperalgesia. There was no spontaneous pain, based on open field behavior. There was a significant increase in opioid-receptor activity.

CONCLUSIONS

DCA induces mild, transient colitis, resulting in persistent visceral hyperalgesia and referred pain in rats, modeling some aspects of postinflammatory IBS.

Altered intestinal permeability in patients with primary fibromyalgia and in patients with complex regional pain syndrome

OBJECTIVES

The pain intensity of patients with FM has recently been reported to be correlated with the degree of small intestinal bacterial overgrowth (SIBO). SIBO is often associated with an increased intestinal permeability (IP). Increased IP, if shown in FM, may have pathogenetic relevance because it leads to the exposure of immune cells to luminal antigens and consequent immune modulation. It is currently unknown whether IP is altered in FM. We therefore examined the IP in a group of patients with primary FM and in two control groups, healthy volunteers and patients with an unrelated chronic pain syndrome, complex regional pain syndrome (CRPS). We hypothesized that patients with FM, but not volunteers or those patients with CRPS, would have altered IP.

METHODS

Both gastroduodenal and small IP were assessed using an established three-sugar test, where urinary disaccharide excretion reflecting intestinal uptake was measured using HPLC.

RESULTS

Forty patients with primary FM, 57 age- and sex-matched volunteers and 17 patients with CRPS were enrolled in this study. In the FM group, 13 patients had raised gastroduodenal permeability and 15 patients had raised small intestinal permeability, but only one volunteer had increased gastroduodenal permeability (P < 0.0001, chi-square test for the three groups). The IP values were significantly increased in the patient groups (P < 0.0003 for all comparisons, one-way analysis of variance).

CONCLUSIONS

The IPs in primary FM and, unexpectedly, CRPS are increased. This study should stimulate further research to determine the implication of altered IP in the disease pathophysiology of FM and CRPS.

Psychophysiology of visceral pain in IBS and health

The psychophysiology of visceral pain as it relates to gastrointestinal motility, visceral sensitivity, and putative mechanisms of the processing of visceral stimuli by the central and peripheral nervous systems are discussed. Peripheral mechanisms may include low-grade mucosal inflammation, and it is likely that central nervous mechanisms such as neuronal plasticity at the level of the spinal cord and attentional bias at the cortical level are relevant for the chronification of visceral pain. From a psychophysiological perspective, visceral pain therefore remains a complex symptom because behavioral variables, such as the way an individual deals with stress, may be as important for the etiology of visceral pain as, for example, a history of inflammation.

Discrepancies between the responses to skin prick test to food and respiratory antigens in two subtypes of patients with irritable bowel syndrome

AIM: To compare the response to skin prick tests (SPTs) to food antigens (FAs) and inhalant allergens (IAs) in patients with two subtypes of irritable bowel syndrome (IBS) and healthy controls.

METHODS: We compared the results of SPTs for IAs and FAs in 87 volunteers divided into three groups: diarrhea predominant IBS (D-IBS) GroupI(n = 19), constipation predominant IBS (C-IBS) Group II (n = 17), and normal controls Group III (n = 51).

RESULTS: Of the 285 tests (171 for FAs and 114 for IAs) performed in GroupIwe obtained 45 (26.3%) positive responses for FA and 23 (20.1%) for IA. Of the 153 tests for FA in Group II, we obtained 66 (20.1%) positive responses, and of the 102 tests for IA, we obtained 20 (19.6%) positive responses. Of the 459 tests for FA performed in Group III, we obtained 39 (84%) positive responses, and of the 306 for IA, we obtained 52 (16.9%) positive responses. The numbers of positive responses were not significantly different between the three groups, but in the D-IBS group, the number of SPT FA responses differed significantly from those for the other two groups (P < 0.01).

CONCLUSION: Despite the small number of cases studied, the higher reactivity to FAs in GroupIcompared to Groups II and III adds new information, and suggests the presence of a possible alteration in intestinal epithelial function.

Development of a travelers' diarrhea vaccine for the military: how much is an ounce of prevention really worth?

Infectious diarrhea is one of the many threats to the deployed military, and given limited resources, a decision to pursue a vaccine acquisition strategy should be based on best evidence that weighs costs and benefits compared to alternatives. An economic model was developed to estimate the marginal cost to avert a duty day lost due to diarrhea for a vaccine acquisition strategy compared to current clinical management, for both multiplex and pathogen-specific vaccines. Vaccines against Campylobacter and enterotoxigenic Escherichia coli appeared to be more favorable than a Shigella vaccine. This model provides an evidence-based decision tool to support prioritization in vaccine development.

A double blind randomized controlled trial of a probiotic combination in 100 patients with irritable bowel syndrome

OBJECTIVES

The purpose of this study was to evaluate the effects of a probiotic combination on symptoms in patients with irritable bowel syndrome (IBS).

METHODS

We investigated the efficiency of a probiotic dietary supplement, containing four strains of lactic acid bacteria, on symptoms of IBS. One hundred and sixteen patients with IBS fulfilling the Rome II criteria were randomized in a parallel group, double-blind study to receive a placebo or a probiotic combination (1 x 10(10) cfu once daily) for four weeks. The symptoms that were monitored weekly included discomfort, abdominal pain, and stool frequency and quality. Quality of life was assessed before and at the end of the treatment using the SF36 and FDD-quality-of-life questionnaires.

RESULTS

One hundred subjects completed the study (48 probiotic combination, 52 placebo). The probiotic combination was not superior to the placebo in relieving symptoms of IBS (42.6 versus 42.3% improvement). However, the decrease of abdominal pain between the first and the fourth week of treatment was significantly higher in probiotic treated patients (-41.9 versus -24.2%, P=0.048). Interesting findings from the IBS sub-groups were also observed such as a lower pain score at end point in patients with alternating bowel habits (P=0.023) and an increase of stool frequency in the constipated sub-group from the first week of probiotic treatment (P=0.043).

CONCLUSIONS

The probiotic combination was not significantly superior to the placebo in relieving symptoms of IBS. Despite the apparent high placebo response, interesting findings from IBS sub-groups were observed in the field of abdominal pain and stool frequency.

Probiotic products in Canada with clinical evidence: what can gastroenterologists recommend?

Probiotics, defined as 'live microorganisms, which when administered in adequate amounts, confer a health benefit on the host', are finally becoming an option for gastroenterologists in Canada, after being available for many years in Japan, Europe and the United States of America. Unfortunately, Health Canada and the US Food and Drug Administration have not controlled the use of the term 'probiotic' or put into place United Nations and World Health Organization guidelines. The net result is that a host of products called 'probiotics' are available but are not truly probiotic. The aim of the present review was to discuss the rationale for probiotics in gastroenterology, and specifically examine which products are options for physicians in Canada, and which ones patients might be using. It is hoped that by clarifying what probiotics are, and the strengths and limitations of their use, specialists will be better placed to make recommendations on the role of these products in patient care. In due course, more clinically documented probiotics will emerge, some with therapeutic effects based on a better understanding of disease processes.