The clinical course of postinfectious irritable bowel syndrome: a five-year follow-up study

Prevalence of irritable bowel syndrome and functional dyspepsia after acute gastroenteritis: systematic review and meta-analysis

OBJECTIVE

Disorders of gut-brain interaction may arise after acute gastroenteritis. Data on the influence of pathogen type on the risk of postinfection IBS (PI-IBS), as on postinfection functional dyspepsia (PI-FD), are limited. We conducted a systematic review and meta-analysis to determine prevalence of PI-IBS or PI-FD after acute gastroenteritis.

DESIGN

We included observational studies recruiting ≥50 adults and reporting prevalence of IBS or FD after acute gastroenteritis with ≥3-month follow-up. A random effects model was used to estimate prevalence and ORs with 95% CIs.

RESULTS

In total, 47 studies (28 170 subjects) were eligible. Overall prevalence of PI-IBS and PI-FD were 14.5% and 12.7%, respectively. IBS persisted in 39.8% of subjects in the long-term (>5 years follow-up) after diagnosis. Individuals experiencing acute gastroenteritis had a significantly higher odds of IBS (OR 4.3) and FD (OR 3.0) than non-exposed controls. PI-IBS was most associated with parasites (prevalence 30.1%), but in only two studies, followed by bacteria (18.3%) and viruses (10.7%). In available studies, Campylobacter was associated with the highest PI-IBS prevalence (20.7%) whereas Proteobacteria and SARS-CoV-2 yielded the highest odds for PI-IBS (both OR 5.4). Prevalence of PI-FD was 10.0% for SARS-CoV-2 and 13.6% for bacteria (Enterobacteriaceae 19.4%).

CONCLUSION

In a large systematic review and meta-analysis, 14.5% of individuals experiencing acute gastroenteritis developed PI-IBS and 12.7% PI-FD, with greater than fourfold increased odds for IBS and threefold for FD. Proinflammatory microbes, including Proteobacteria and subcategories, and SARS-CoV-2, may be associated with the development of PI-IBS and PI-FD.

Risk Factors of Developing Postinfectious Irritable Bowel Syndrome in Shigellosis Patients, 5 Years After Hospitalization During the Outbreak

Background

Irritable bowel syndrome (IBS) can be triggered by bacterial dysentery. This study aimed to investigate postinfectious IBS and its risk factors after the shigellosis outbreak in hospitalized patients.

Methods

This retrospective study was conducted in 2020-2021 in referral hospitals for Shigella gastroenteritis during the 2014 shigellosis outbreak in Isfahan. The Shigella-infected group included hospitalized shigellosis patients with clinical symptoms and positive stool culture. The control group included patients matched pairwise on age and sex to the Shigella-infected group, admitted to the same hospitals in the same period with diagnoses other than shigellosis. Both groups had no history of diagnosed IBS before the outbreak. The incidence of IBS (according to Rome-III criteria) and its related factors was compared between the 2 groups 5 years after infection.

Results

Of 619 participants, 220 (35.5%) were in the Shigella-infected group. The 5-year incidence of IBS was 31.8% and 5.7% in the Shigella-infected and control groups, respectively. Multivariate analysis showed that shigellosis was significantly associated with increased risk of IBS (odds ratio [OR], 17.18 [95% confidence interval {CI}, 9.37-31.48]). Multivariate analysis indicated education level (OR, 4.15 [95% CI, 1.47-11.73]), diarrhea lasting >4 days (OR, 1.69 [95% CI, 1.17-2.44]), and abdominal cramps during the infection (OR, 0.27 [95% CI, .77-.95]) associated with postinfectious IBS (P < .05).

Conclusions

Hospitalized patients with Shigella gastroenteritis are at increased risk of IBS within 5 years after infection. Factors such as higher education level and the absence of abdominal cramps and diarrhea persisting for >5 days during hospitalization can further increase this risk.

Postinfection Irritable Bowel Syndrome

Following acute gastroenteritis (AGE) due to bacteria, viruses, or protozoa, a subset of patients develop new onset Rome criteria positive irritable bowel syndrome (IBS), called postinfection IBS (PI-IBS). The pooled prevalence of PI-IBS following AGE was 11.5%. PI-IBS is the best natural model that suggests that a subset of patients with IBS may have an organic basis. Several factors are associated with a greater risk of development of PI-IBS following AGE including female sex, younger age, smoking, severity of AGE, abdominal pain, bleeding per rectum, treatment with antibiotics, anxiety, depression, somatization, neuroticism, recent adverse life events, hypochondriasis, extroversion, negative illness beliefs, history of stress, sleep disturbance, and family history of functional gastrointestinal disorders (FGIDs), currently called disorder of gut-brain interaction. Most patients with PI-IBS present with either diarrhea-predominant IBS or the mixed subtype of IBS, and overlap with other FGIDs, such as functional dyspepsia is common. The drugs used to treat non-constipation IBS may also be useful in PI-IBS treatment. Since randomized controlled trials on the efficacy of drugs to treat PI-IBS are rare, more studies are needed on this issue.

The disease burden associated with Campylobacter spp. in Germany, 2014

Bacteria of the genus Campylobacter are an important cause of human illness worldwide. Campylobacter infections are expressed as gastroenteritis and can lead to severe sequelae like reactive arthritis, Guillain-Barré syndrome, irritable bowel syndrome and inflammatory bowel disease. In Germany, Campylobacter-associated gastroenteritis cases are notifiable but there is no reporting obligation for the sequelaes and the disease burden is clearly underestimated. The aim of our study was to quantify reliably the current disease burden of all Campylobacter spp.-associated diseases for Germany with the method of disability-adjusted life years (DALYs). DALYs combine mortality and morbidity in a single summary measure, whereby one DALY represents the loss of one year in full health. For acute gastroenteritis, we estimated 967 DALYs of which only 484 DALYs were detected within the reporting system. Overall, we estimated that 8811 DALYs were caused by the campylobacter-related diseases known so far. 98% of the DALYs were associated with morbidity and 2% with mortality. Mortality was caused by the health outcomes Gastroenteritis and Guillain-Barré syndrome exclusively.

Systematic review with meta-analyses: does the pathogen matter in post-infectious irritable bowel syndrome?

Objective: Acute gastroenteritis (AGE) is a risk factor for post-infectious irritable bowel syndrome (PI-IBS). This systematic review evaluates the prevalence and risk-factors of PI-IBS after AGE by specific pathogens. Materials and methods: Medline (1966-2019) and Embase (1974-2019) were searched for studies evaluating PI-IBS minimum 3 months after AGE with Campylobacter spp., Salmonella spp., Shigella spp., Escherischia coli, Clostridium difficile, norovirus, rotavirus, Cryptosporidium spp. or Giardia intestinalis using validated criteria for IBS. Pooled prevalence (PP), odds ratios (OR) and risk factors were determined for single pathogens, groups of bacteria, viruses and parasites, and overall for AGE caused by any pathogen. Random-effect models were used for meta-analyses. Results: A total of 34 articles were included. PP of PI-IBS after Campylobacter spp. was 12% (confidence interval 95% [CI]: 10-15%), Salmonellosis 12% (CI: 9-15%), Shigellosis 11% (CI: 8-15%), C. difficile 14% (CI: 4-29%) and E. coli spp. 12% (CI: 5-20%). OR of PI-IBS after salmonellosis was 5.5 (CI: 2.3-12.8) and after shigellosis 13.8 (CI: 4.2-45.4). Bacterial AGE overall showed OR 5.8 (CI: 4.0-8.3) and AGE caused by any pathogen OR 4.9 (CI: 3.9-6.1). Few studies exist on viral and parasitic gastroenteritis. Conclusions: Current literature show similar risks for bacterial pathogens. Studies are limited for viral and parasitic pathogens. The evaluated risk-factors for PI-IBS varied among the included studies and the existing evidence is insufficient to identify pathogen-specific risk factors.

A prospective study on incidence, risk factors, and validation of a risk score for post-infection irritable bowel syndrome in coastal eastern India

BACKGROUND AND AIM

Post-infection irritable bowel syndrome (PI-IBS) can occur following acute gastroenteritis (AGE). This study was designed to evaluate the incidence and risk factors of PI-IBS following AGE and to validate a PI-IBS risk score.

METHODS

This prospective study was performed between September 2014 and October 2016 on AGE patients by documenting their AGE severity and following up after 3 and 6 months to study the development of IBS (ROME III criteria). The risk score was calculated for all the subjects, and its discrimination ability was tested.

RESULTS

Out of 136 hospitalized AGE patients, 35 developed PI-IBS after 6 months. The factors associated with PI-IBS were younger age, longer duration of AGE, anxiety, depression, abdominal pain, bloody stool, vomiting, fever, family history of IBS, and positive stool culture (univariate analysis); however, on multivariate analysis, younger age (adjusted odds ratio [AOR] 0.5; p 0.03), prolonged duration of AGE (AOR 8.6; p 0.01), and abdominal cramps (AOR 2.1; p 0.02) were the independent factors influencing its occurrence. PI-IBS occurred even after infection with Vibrio cholerae. The PI-IBS risk score was significantly higher in patients who developed PI-IBS (72.4 ± 14.48 vs. 31.56 ± 20.4, p-value < 0.001); score > 50 had a sensitivity and specificity of 91.4% and 84.2%, respectively.

CONCLUSION

One fourth of AGE patients developed PI-IBS after 6 months. Factors influencing its development were younger age, long duration of AGE, and abdominal pain. The PI-IBS risk score had good predictive accuracy in our population.

Rome Foundation Working Team Report on Post-Infection Irritable Bowel Syndrome

BACKGROUND & AIMS

The existence of postinfection irritable bowel syndrome (PI-IBS) has been substantiated by epidemiology studies conducted in diverse geographic and clinical settings. However, the available evidence has not been well summarized, and there is little guidance for diagnosis and treatment of PI-IBS. The ROME Foundation has produced a working team report to summarize the available evidence on the pathophysiology of PI-IBS and provide guidance for diagnosis and treatment, based on findings reported in the literature and clinical experience.

METHODS

The working team conducted an evidence-based review of publication databases for articles describing the clinical features (diagnosis), pathophysiology (intestinal sensorimotor function, microbiota, immune dysregulation, barrier dysfunction, enteroendocrine pathways, and genetics), and animal models of PI-IBS. We used a Delphi-based consensus system to create guidelines for management of PI-IBS and a developed treatment algorithm based on published findings and experiences of team members.

RESULTS

PI-IBS develops in about 10% of patients with infectious enteritis. Risk factors include female sex, younger age, psychological distress during or before acute gastroenteritis, and severity of the acute episode. The pathogenesis of PI-PBS appears to involve changes in the intestinal microbiome as well as epithelial, serotonergic, and immune system factors. However, these mechanisms are incompletely understood. There are no evidence-based, effective pharmacologic strategies for treatment of PI-IBS. We provide a consensus-based treatment algorithm, based on clinical presentation and potential disease mechanisms.

CONCLUSIONS

Based on a systematic review of the literature and team experience, we summarize the clinical features, pathophysiology (from animal models and human studies), and progression of PI-IBS. Based on these findings, we present an algorithm for diagnosis and treatment of PI-IBS based on team consensus. We also propose areas for future investigation.

Long-Term Gastrointestinal Consequences are Frequent Following Sporadic Acute Infectious Diarrhea in a Tropical Country: A Prospective Cohort Study

BACKGROUND

Postinfection irritable bowel syndrome (PI-IBS) and functional dyspepsia (PI-FD), though reported from the temperate countries, have not been studied in the tropics; PI-malabsorption syndrome (MAS), which mimics PI-IBS, is reported from the tropics. No report till date on PI-IBS excluded PI-MAS. We studied: (i) the frequency of continuing bowel dysfunction after acute gastroenteritis (AG), (ii) its predictors, and (iii) PI-MAS among patients with PI-IBS.

METHODS

345 consecutive subjects each, with AG and age- and gender-matched healthy controls were followed up 3-monthly for 12 months using a translated-validated questionnaire and functional gastrointestinal disorders (FGIDs) were diagnosed by Rome III criteria. Symptom duration >3 months but <6 months was diagnosed as chronic bowel dysfunction (CBD) and dyspeptic symptoms, respectively. MAS was diagnosed if 2/3 tests (D-xylose H2 breath test, Sudan III-stained stool microscopy, and duodenal histology) were abnormal. Fecal microbiological studies were performed in 245/345 (71%) patients.

RESULTS

AG patients more often developed PI-IBS and PI-FD than controls (16.5 vs. 2.6% and 7.4 vs. 0.6%, respectively; p<0.001). Presence of FD was a risk factor for PI-IBS and IBS for PI-FD. On multivariate analysis, dyspeptic symptoms, CBD, and weight loss were the risk factors for PI-FGIDs. The frequency of PI-IBS following Vibrio cholera and other bacterial infection was comparable. Malabsorption was present among 2/23 (9%) patients with PI-IBS.

CONCLUSION

FGIDs are common after AG; dyspeptic symptoms, CBD, and weight loss were risk factors for PI-FGIDs. Vibrio cholerae infection caused PI-FGID, which was never reported. About 9 % patients fulfilling the criteria for PI-IBS had PI-MAS.

Cost of Illness for Five Major Foodborne Illnesses and Sequelae in Sweden

OBJECTIVES

The main objective of this study was to derive cost estimates of five major foodborne illnesses (campylobacteriosis, salmonellosis, enterohemorrhagic Escherichia coli (EHEC), yersiniosis and shigellosis) in Sweden. These estimates provide a necessary contribution to perform future cost-benefit analyses aimed at reducing the burden of foodborne disease. A secondary aim was to obtain estimates of the true number of cases that occur in the community, thus providing necessary ground for calculating costs.

METHODS

The true number of cases for each foodborne illness was simulated by multiplying the reported number of cases by sequential multipliers, one for each potential source of information loss about a case. This assessment of the true number of cases was then used to estimate the number of cases of sequelae for each illness. An incidence-based analysis was then used to calculate direct medical and non-medical costs, as well as indirect costs. Data for estimating the true number of cases for each illness were primarily based on an expert panel, while the derivation of costs mainly utilized national registries, databases and published literature.

RESULTS

The estimated number of cases was between 7- and 11-fold higher than the reported number of cases, indicating the importance of taking information loss into account when calculating costs. By far the most common pathogen of the five was campylobacter, with an estimated 101,719 (90% credibility interval [CI] 59,640-158,025) human cases occurring annually. For salmonella, 19,678 (90% CI 8394-40,456) cases were estimated to occur each year, while the other three pathogens were less common, with a yearly incidence of approximately 2500-5500 cases each. The total cost for the five pathogens (including sequelae) amounted to €142 million annually. Campylobacter was the most costly pathogen, representing 69% of the total costs. Salmonellosis and EHEC constituted 18 and 9% of these costs, respectively, while yersiniosis and shigellosis represented approximately 2% each. Costs for sequelae were significant and accounted for approximately 50% of the total costs.

CONCLUSIONS

Our simulations indicated that campylobacter infection was more common and more costly than salmonella, EHEC, yersinia and shigella combined. Estimated costs for all illnesses were highly influenced by (1) considering potential information losses about cases in the population (which increased costs 7- to 11-fold), and (2) taking account of post-infection sequelae (which doubled the costs).

Shigellosis

Shigellosis is a clinical syndrome caused by invasion of the epithelium lining the terminal ileum, colon, and rectum by Shigella species. Although infections occur globally, and in people of all ages, endemic infections among children aged 1-4 years living in low-income and middle-income settings constitute most of the disease burden. The versatile manifestations of these highly contagious organisms range from acute watery diarrhoea to fulminant dysentery characterised by frequent scant bloody stools with fever, prostration, and abdominal cramps. A broad array of uncommon, but often severe, intestinal and extraintestinal complications can occur. Despite marked reductions in mortality during the past three decades, there are roughly 164 000 annual deaths attributable to shigellosis. Intercontinental dissemination of multiresistant shigella strains, facilitated by travellers and men who have sex with men, has prompted new recommendations for antibiotic therapy. Awareness of disease burden and the emerging threats posed by shigella have accelerated interest in development of shigella vaccines, many of which are being tested in clinical trials.

The effectiveness of empirical anti-parasitic treatment in returning travellers with persistent abdominal symptoms

BACKGROUND

Persistent abdominal symptoms (PAS) are common among returning-travellers. In the absence of sensitive tests to identify intestinal parasites, gastrointestinal (GI) symptoms often remain a diagnostic challenge. In this study we examined the effectiveness of empirical anti-parasitic treatment in returning-travellers with PAS despite no positive stool-test.

METHODS

A retrospective study among returning travellers who approached the clinic between the years 2014 and 2016 with GI complaints without a positive stool-test. The empirical treatment included broad-spectrum anti-parasitic agents-oral Tinidazole and Albendazole. A follow-up questionnaire was performed at least 6 months post-treatment.

RESULTS

A total of 102 patients responded the questionnaire-50% women; average age 31.14 (±12.20) years. The average duration of complaints before treatment was 16.52 (±30.06) months. Common GI symptoms included abdominal pain (83.3%) and diarrhoea (78.4%); 67.6% of the patients complained of extreme fatigue. Overall, 69% of the patients reported an improvement in GI symptoms, 37% of them reported full recovery within a few weeks post-treatment. Furthermore, there was an improvement in the energy level and general well-being in 68% and 70% of the patients, respectively. Only 33% of the patients reported minor side effects related to the treatment.

CONCLUSIONS

The improvement in GI symptoms, energy level and general well-being shortly after anti-parasitic treatment justifies this empirical approach in returning-travellers with PAS despite negative stool-tests. The association between fatigue and PAS post-travel and the improvement in both as a response to treatment defines fatigue as part of a new syndrome-'Post-travel fatigue and abdominal symptoms'.

Postinfection Irritable Bowel Syndrome: The Links Between Gastroenteritis, Inflammation, the Microbiome, and Functional Disease

Postinfection irritable bowel syndrome (PI-IBS) is a diarrheal disease that develops after infectious gastroenteritis (IGE). Profound alterations in the microbiota accompany IGE yet only 10% of IGE patients progress to PI-IBS. This review explores research linking IGE severity, psychological comorbidity, PI-IBS, and the microbiome in various patient populations. Selective pressures caused by inflammation and increased gastrointestinal motility during gastroenteritis can alter intestinal bacterial phyla including Bacteroidetes, Firmicutes, and Proteobacteria. More specifically, classes such as Bacteroides and Clostridia are differentially abundant in many PI-IBS patients. Altered microbiota may perpetuate a cycle of enteric and systemic inflammation, potently activating neural afferent signaling in the enteric nervous system and causing pain and diarrhea in PI-IBS patients. Altered production of microbial metabolites, for example short chain fatty acids, may have enteric and systemic effects on the host. Longitudinal sampling to characterize changes in the microbiota's genetic, metabolic, and transcriptional activities over time from IGE to PI-IBS may enable improved diagnosis and classification of PI-IBS cases into subtypes, allowing for targeted antibiotic, probiotic, and prebiotic treatments. PI-IBS is a heterogenous and largely organic disease marked by specific alterations in functions of the microbiota and is an important model for studying microbial influences on intestinal, neurological, and psychological host functions.

Smoking in Irritable Bowel Syndrome: A Systematic Review

OBJECTIVE

The aim of this review was to examine (1) the prevalence of smoking in subjects with irritable bowel syndrome (IBS), (2) whether smoking prevalence significantly differs between subjects with and without IBS, and (3) whether smoking significantly predicts the presence or the development of IBS.

METHODS

Articles were retrieved by systematically searching the Scopus, Web of Science, and PubMed electronic databases from inception to July 2016, using the keywords "smoking" and "tobacco" combined with "irritable bowel syndrome." Reference lists of included articles were also searched. Articles were included if they (1) reported data on smoking prevalence in subjects with IBS and/or on the association (assessed by means of multivariate analyses) between smoking and IBS, (2) identified IBS according to Manning criteria or Rome I-III criteria, (3) were English-language articles, and (4) involved only adult subjects.

RESULTS

The electronic searches yielded a total of 1,637 records, and 42 articles met inclusion criteria. Another 13 articles were retrieved through manual search, leading to a total of 55 included articles. Smoking prevalence in subjects with IBS was assessed by 48 articles and ranged from 0% in university students to 47.1% in patients with microscopic colitis. Thirty-three articles compared smoking prevalence between subjects with and without IBS. In 25 articles no significant difference was found. In seven articles smoking was significantly more frequent in subjects with IBS compared to those without IBS, while one study found a significantly higher smoking prevalence in controls. Eighteen multivariate analyses assessing the association between smoking and IBS were presented in 16 articles. Only one study employed a prospective design. In 11 analyses, smoking was not significantly associated with IBS after adjusting for covariates. In seven studies smoking independently predicted the presence of IBS.

CONCLUSIONS

According to the selected articles, a significant association between smoking and IBS cannot be confirmed. However, different shortcomings may hinder generalizability and comparability of many studies. A dimensional assessment of smoking, a prospective design, the differentiation between IBS subgroups, and the recruitment of patients in clinical settings, especially in primary care, are necessary to clarify the role of smoking in IBS.

Post-infectious IBS, tropical sprue and small intestinal bacterial overgrowth: the missing link

Evidence is emerging that IBS, a hitherto enigmatic disorder thought to be predominantly related to psychological factors, has a microorganic basis in a subset of patients with the disease. Post-infectious IBS (PI-IBS), commonly of the diarrhoea-predominant subtype (defined as new development of IBS following acute infectious diarrhoea), is one such condition known to occur in up to 10-30% individuals after acute gastroenteritis. However, following acute infectious gastroenteritis, patients can also develop post-infectious malabsorption syndrome (PI-MAS), popularly known as tropical sprue. As no study on PI-IBS has rigorously excluded tropical sprue by appropriate investigations, including small intestinal biopsy, the frequency of tropical sprue among patients with PI-IBS is not known. Small intestinal bacterial overgrowth (SIBO) has been suggested to be associated with IBS in general, and in particular diarrhoea-predominant IBS, including PI-IBS. SIBO is also known to be associated with tropical sprue. As both IBS, particularly the subset probably associated with SIBO, and tropical sprue improve with antibiotic treatment, we provide evidence and an explanatory model to support a link among these disorders.

Prevalence, Risk Factors, and Outcomes of Irritable Bowel Syndrome After Infectious Enteritis: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Foodborne illness affects 15% of the US population each year, and is a risk factor for irritable bowel syndrome (IBS). We evaluated risk of, risk factors for, and outcomes of IBS after infectious enteritis.

METHODS

We performed a systematic review of electronic databases from 1994 through August 31, 2015 to identify cohort studies of the prevalence of IBS 3 months or more after infectious enteritis. We used random-effects meta-analysis to calculate the summary point prevalence of IBS after infectious enteritis, as well as relative risk (compared with individuals without infectious enteritis) and host- and enteritis-related risk factors.

RESULTS

We identified 45 studies, comprising 21,421 individuals with enteritis, followed for 3 months to 10 years for development of IBS. The pooled prevalence of IBS at 12 months after infectious enteritis was 10.1% (95% confidence interval [CI], 7.2-14.1) and at more than 12 months after infectious enteritis was 14.5% (95% CI, 7.7-25.5). Risk of IBS was 4.2-fold higher in patients who had infectious enteritis in the past 12 months than in those who had not (95% CI, 3.1-5.7); risk of IBS was 2.3-fold higher in individuals who had infectious enteritis more than 12 months ago than in individuals who had not (95% CI, 1.8-3.0). Of patients with enteritis caused by protozoa or parasites, 41.9% developed IBS, and of patients with enteritis caused by bacterial infection, 13.8% developed IBS. Risk of IBS was significantly increased in women (odds ratio [OR], 2.2; 95% CI, 1.6-3.1) and individuals with antibiotic exposure (OR, 1.7; 95% CI, 1.2-2.4), anxiety (OR, 2; 95% CI, 1.3-2.9), depression (OR, 1.5; 95% CI, 1.2-1.9), somatization (OR, 4.1; 95% CI, 2.7-6.0), neuroticism (OR, 3.3; 95% CI, 1.6-6.5), and clinical indicators of enteritis severity. There was a considerable level of heterogeneity among studies.

CONCLUSIONS

In a systematic review and meta-analysis, we found >10% of patients with infectious enteritis develop IBS later; risk of IBS was 4-fold higher than in individuals who did not have infectious enteritis, although there was heterogeneity among studies analyzed. Women-particularly those with severe enteritis-are at increased risk for developing IBS, as are individuals with psychological distress and users of antibiotics during the enteritis.

Gut-derived cholecystokinin contributes to visceral hypersensitivity via nerve growth factor-dependent neurite outgrowth

BACKGROUND AND AIM

Irritable bowel syndrome is characterized by abdominal pain and altered bowel habits and may occur following stressful events or infectious gastroenteritis such as giardiasis. Recent findings revealed a link between cholecystokinin (CCK), neurotrophin synthesis, and intestinal hyperalgesia. The aim was to investigate the role of CCK in visceral hypersensitivity using mouse models challenged with a bout of infection with Giardia lamblia or psychological stress, either alone or in combination.

METHODS

Abdominal pain was evaluated by visceromoter response to colorectal distension. Nerve fibers in intestinal tissues were stained using immunohistochemistry (PGP9.5). Human neuroblastoma SH-SY5Y cells incubated with bacterial-free mouse gut supernatant or recombinant CCK-8S were assessed for neurite outgrowth and nerve growth factor (NGF) production.

RESULTS

Intestinal hypersensitivity was induced by either stress or Giardia infection, and a trend of increased pain was seen following dual stimuli. Increased CCK levels and PGP9.5 immunoreactivity were found in colonic mucosa of mice following stress and/or infection. Inhibitors to the CCK-A receptor (L-364718) or CCK-B receptor (L-365260) blocked visceral hypersensitivity caused by stress, but not when induced by giardiasis. Nerve fiber elongation and NGF synthesis were observed in SH-SY5Y cells after incubation with colonic supernatants from mice given the dual stimuli, or after treatment with CCK-8S. Increased nerve fiber length by colonic supernatant and CCK-8S was attenuated by L-365260 or neutralizing anti-NGF.

CONCLUSIONS

This new model successfully recapitulates intestinal hypernociception induced by stress or Giardia. Colonic CCK contributes to visceral hypersensitivity caused by stress, but not by Giardia, partly via NGF-dependent neurite outgrowth.

Long-term Clinical Course of Post-infectious Irritable Bowel Syndrome After Shigellosis: A 10-year Follow-up Study

Background/Aims

A limited number of studies are available regarding the long-term natural history of post-infectious irritable bowel syndrome (PI-IBS). We aimed to investigate the long-term clinical course of PI-IBS.

Methods

A prospective cohort study was conducted from a 2001 shigellosis outbreak in a Korean hospital with about 2000 employees. A cohort of 124 hospital employees who were infected by Shigella sonnei due to contaminated food in the cafeteria, and 105 sex- and age-matched, non-infected, controls were serially followed for their bowel symptoms by questionnaire surveys for 10 years.

Results

The Shigella-infected cohort showed significantly higher odds ratio for irritable bowel syndrome (IBS) at 1-year (11.90; 95% CI, 1.49–95.58) and 3-year (3.93; 95% CI, 1.20–12.86) follow-up, compared to their controls. However, corresponding odds ratio for PI-IBS was not significantly increased at 5-year (1.88; 95% CI, 0.64–5.54) and 8-year (1.87; 95% CI, 0.62–5.19) follow-up. At 10-year follow-up survey, the prevalence of IBS was similar for the Shigella-infected cohort and their controls (23.3% versus 19.7%, P = 0.703). Risk factors which were independently associated with PI-IBS among the Shigella-infected cohort included younger age, previous history of functional bowel disorder, and longer duration of diarrhea at baseline.

Conclusions

Patients who were infected by Shigella sonnei experienced significantly increased risk of IBS until 3 years after shigellosis, and modestly increased risk until 8 years, but showed similar risk of IBS with uninfected controls at 10 years post-infection. PI-IBS is quite a chronic disorder, and follows a long-term natural course.

Traveler's Diarrhea

Traveler's diarrhea (TD) is the most common travel-related illness, and it can have a significant impact on the traveler. Pretravel consultation provides an excellent opportunity for the clinician to counsel the traveler and discuss strategies such as food and water hygiene, vaccinations, and medications for prophylaxis or self-treatment that may decrease the incidence and impact of TD. Postinfectious sequelae, such as postinfectious irritable bowel syndrome, reactive arthritis, and Guillain-Barre syndrome, may develop weeks or months after return.

Increased risk of functional gastrointestinal sequelae after Clostridium difficile infection among active duty United States military personnel (1998-2010)

BACKGROUND & AIMS

Some acute enteric infections are associated with the development of functional gastrointestinal disorders, most commonly irritable bowel syndrome but also other functional and organic gastrointestinal sequelae. Clostridium difficile infection has increased in incidence and severity, however, few studies have evaluated functional disorders after this infection.

METHODS

We evaluated the epidemiology and sequelae of C difficile in the US military population by using the US Department of Defense's Armed Forces Health Surveillance Center Defense Medical Ecounter Database. We then performed a retrospective cohort study of 891 active-duty US military personnel who developed C difficile from 1998 to 2010 and 3231 matched subjects who had not been exposed to C difficile. Subjects were identified based on International Classification of Diseases, 9th revision, Clinical Modification codes for C difficile disease.

RESULTS

C difficile was associated independently with increased rate ratios (RRs) for incident irritable bowel syndrome (RR, 6.1; 95% confidence interval [CI], 2.9-12.9), gastroesophageal reflux disease (GERD) (RR, 1.9; 95% CI, 1.4-2.6), dyspepsia (RR, 3.3; 95%, 1.4-7.7), and constipation (RR, 2.2; 95% CI, 1.3-3.7). Approximately 14.1% of subjects with C difficile later were identified with one of these functional gastrointestinal disorders (FGDs), compared with 6% of controls. Community- and health care-associated C difficile were associated at similar rates with these sequelae. Patients were at increased risk for FGDs within 3 months of a C difficile episode, with one additional case of FGD developing for every 12 diagnoses of C difficile.

CONCLUSIONS

The incidence of community- and health care-associated C difficile has increased in the US military population from 1998 through 2010. As for other gastrointestinal infections, C difficile disease is associated with clinically relevant functional sequelae in this military population.

An assessment of the human health impact of seven leading foodborne pathogens in the United States using disability adjusted life years

We explored the overall impact of foodborne disease caused by seven leading foodborne pathogens in the United States using the disability adjusted life year (DALY). We defined health states for each pathogen (acute illness and sequelae) and estimated the average annual incidence of each health state using data from public health surveillance and previously published estimates from studies in the United States, Canada and Europe. These pathogens caused about 112 000 DALYs annually due to foodborne illnesses acquired in the United States. Non-typhoidal Salmonella (32 900) and Toxoplasma (32 700) caused the most DALYs, followed by Campylobacter (22 500), norovirus (9900), Listeria monocytogenes (8800), Clostridium perfringens (4000), and Escherichia coli O157 (1200). These estimates can be used to prioritize food safety interventions. Future estimates of the burden of foodborne disease in DALYs would be improved by addressing important data gaps and by the development and validation of US-specific disability weights for foodborne diseases.

Immunological Biomarkers in Postinfectious Irritable Bowel Syndrome

BACKGROUND

There is a recognized need for biological markers to facilitate diagnoses of irritable bowel syndrome (IBS) and to distinguish it from other functional and organic disorders. As postinfectious IBS (PI-IBS) is believed to account for as many as one third of all IBS cases, here we sought to identify differences in specific cytokines and serologic responses across patients with idiopathic IBS and PI-IBS and healthy controls.

METHODS

At total of 120 US military personnel were identified from the Defense Medical Surveillance System-based International Classification of Diseases, 9th Revision, Clinical Modification (ICD9-CM) codes recorded during medical encounters and were grouped based on infectious gastroenteritis (IGE) episode (Shigella, Campylobacter, Salmonella, or an unspecified pathogen) followed by IBS, IBS without antecedent IGE, or IGE without subsequent IBS within 2 years of the IGE exposure. Sera from subjects were assayed for cytokine levels and antibodies against a panel of microbiome antigens.

RESULTS

In total, 10 of 118 markers considered were shown to differ between IBS patients and healthy controls, including cytokines interleukin-6 (IL-6), IL-8, IL-1β, and macrophage inflammatory protein-1β (MIP-1β), as well as antibody responses to microbial antigens. Antimicrobial antibody response profiles also differed between PI-IBS cases compared with IBS cases without an antecedent episode of acute IGE. Comparisons also suggest that immunoglobulin A (IgA) and IgG profiles may point to pathogen-specific origins among PI-IBS cases.

CONCLUSION

Taken together, these results provide further evidence as to the molecular distinctness of classes of IBS cases and that serum biomarkers may prove useful in elucidating their pathobiological pathways.

Incidence and predictive factors of irritable bowel syndrome after acute diverticulitis in Korea

PURPOSE

Evidence indicates that irritable bowel syndrome can occur after gastroenteritis. However, little is known about its incidence after diverticulitis. This study was designed to identify the incidence and risk factors of irritable bowel syndrome after diverticulitis in Korea.

METHODS

A survey regarding irritable bowel syndrome was performed in patients allocated to the cases hospitalized for acute diverticulitis and controls hospitalized for non-gastrointestinal disorders between January 2007 and June 2012. Patients meeting criteria for irritable bowel syndrome before hospitalization or with a history of bowel resection were excluded for analysis. Response rate of telephone interviews was 28.1 % (139 of 494) and 73.3 % (220 of 300) in cases and controls, respectively. After exclusion, 102 patients in the cases and 205 patients in the controls were analyzed.

RESULTS

At 31 months median follow-up, irritable bowel syndrome had developed in 13 patients (12.8 %) in the cases and 11 patients (5.4 %) in the controls with significant statistical difference (p = 0.02). No clinical difference was seen between the two groups. No clinical factor was significant for the development of irritable bowel syndrome after diverticulitis, and no independent factor was associated with the development of irritable bowel syndrome. Among the 13 patients who developed post-diverticulitis irritable bowel syndrome, the diarrhea-predominant type (53.9 %) was most common.

CONCLUSION

A higher incidence of irritable bowel syndrome after diverticulitis was evident in this study. However, no clinical feature for prediction of its development after diverticulitis was found. Further large-scale analysis will be needed to generalize this result.

Economic effects of introducing alternative Salmonella control strategies in Sweden

The objective of the study was to analyse the economic effects of introducing alternative Salmonella control strategies in Sweden. Current control strategies in Denmark and the Netherlands were used as benchmarks. The true number of human Salmonella cases was estimated by reconstructing the reporting pyramids for the various scenarios. Costs were calculated for expected changes in human morbidity (Salmonella and two of its sequelae), for differences in the control programmes and for changes in cattle morbidity. The net effects (benefits minus costs) were negative in all scenarios (€ -5 to -105 million), implying that it would not be cost-effective to introduce alternative control strategies in Sweden. This result was mainly due to an expected increase in the incidence of Salmonella in humans (6035-57108 reported and unreported new cases/year), with expected additional costs of € 5-55 million. Other increased costs were due to expected higher incidences of sequelae (€ 3-49 million) and a higher cattle morbidity (€ 4-8 million). Benefits in terms of lower control costs amounted to € 4-7 million.

Relationship between infectious gastroenteritis and irritable bowel syndrome

A newly recognized causative factor in a subset of patients with irritable bowel syndrome (IBS) is called post-infectious IBS (PI-IBS). IBS symptoms frequently develop after an acute episode of infectious gastroenteritis. Several studies have been made in our understanding of the concept of PI-IBS. Recent studies suggest that transient or chronic gastrointestinal inflammation may play a role in IBS pathogenesis. PI-IBS can be regarded as a natural experiment model in which an insult in the form of an infective disease impacts on subjects with underlying genetic and psychosocial predispositions who then develop IBS. IBS is likely to be a complex trait wherein variability in clinical presentation is partially explained by heterogeneity in underlying genetic and environmental risk factors for PI-IBS. Further studies on PI-IBS are needed to understand the pathophysiology of functional gastrointestinal disorders and to develop new promising management for such patients.

Investigation of the effect of military stress on the prevalence of functional bowel disorders

AIM: To investigate the morbidity of functional bowel disorders (FBD) under military stress conditions in order to lay foundations for the prevention and treatment of this disease.

METHODS: Four hundred and fifty-seven soldiers who were assigned to specified services and 471 soldiers who were assigned to routine services were enrolled using cluster sampling, with the latter as a control group. They were surveyed using the Rome III FBD standard questionnaire. The FBD symptom questionnaire included FBD-related symptoms, severity, duration or attack time, and accompanying symptoms.

RESULTS: The morbidity of the military stress group (14.6%) was significantly higher than in the control group (9.98%) (χ² = 4.585, P < 0.05). The incidence of smoking, abdominal pain and acid regurgitation (χ² = 4.761, P < 0.05) as well as the ZUNG anxiety/depression scores (χ² = 7.982, P < 0.01) were also significantly higher in the military stress group compared with the control group. ZUNG anxiety (χ² = 11.523, P < 0.01) and depression (χ² = 5.149, P < 0.05) scores were higher in the FBD group compared with the non-FBD group. The differences in the ZUNG self-rated anxiety and depression scales between the 2 groups were statistically significant (χ² = 14.482, P < 0.01 and χ² = 6.176, P < 0.05).

CONCLUSION: The morbidity of FBD was higher under military stress conditions.

Editorial: From the acute infection to the chronic disorder "Don't worry it's just a viral gastroenteritis"

Postinfectious functional gastrointestinal disorders (PI-FGID) have become a category in the general FGID classification. Bacterial PI-FGID has been well documented in several studies and meta-analysis. Increased risk does not appear to be confined to bacterial gastroenteritis (GE), also protozoan and helminth infections are sometimes followed by PI-FGID. In this issue of the journal, Zanini et al. provides evidence that Norovirus GE also leads to the development of PI-irritable bowel syndrome in a substantial proportion of patients.

Gastrointestinal infections and the development of irritable bowel syndrome

PURPOSE OF REVIEW

Approximately 10% of the millions of persons with functional gastrointestinal disorders (FGDs) including irritable bowel syndrome (IBS) had their illness onset following an acute bout of infectious diarrhea and are referred to as having postinfectious (PI) FGD or PI-IBS. Recent studies have helped to identify the pathogenesis and natural history of these disorders.

RECENT FINDINGS

Groups of patients with acute diarrhea or dysentery (passage of grossly bloody stools) are being followed for development of PI-IBS. Persistent mucosal inflammation, air trapping in the gut, and alteration of intestinal motility contribute to the disease symptoms in genetically susceptible persons. The prognosis of postinfectious forms of IBS is more favorable compared with people with idiopathic forms of the disorder.

SUMMARY

With full characterization of postdiarrhea forms of FGDs, we should be able to define the mechanisms of disease early in the course of chronic illness and to better understand the more common idiopathic forms of the disease. We are likely to identify specific alteration of gut pathophysiology in postinfectious FGDs and to then classify them not as a poorly characterized group of functional disorders but as specific gastrointestinal disorders.

Postinfectious irritable bowel syndrome: follow-up of a patient cohort of confirmed cases of bacterial infection with Salmonella or Campylobacter

BACKGROUND

Gastrointestinal infections have been proposed to predict subsequent irritable bowel syndrome (IBS) but large-scale infectious events are rare and long-term data are missing.

METHODS

We identified 576 individuals with a Salmonella or Campylobacter infection between 2000 and 2009 that were followed by a short postal questionnaire asking for the presence of current symptoms in 2010. In case of agreement (n = 90), an extended postinfectious (PI)-IBS questionnaire was mailed including the Hospital Anxiety Depression Scale and the Patient Health Questionnaire.

KEY RESULTS

A total of 189 patients reported back (36%); 98 had a Salmonella and 91 had a Campylobacter infection, of which 56 reported persistent symptoms (9.7% of the initial sample). Fifty-one patients returned the PI-IBS questionnaire. Of 48 patients with complete data, 15 reported no or mild symptoms of abdominal pain or discomfort while 17 had moderate and 16 severe symptoms. Twenty-two met Rome IBS criteria, 14 (29%) reported GI symptoms before the infection. Patients with moderate and/or severe PI-IBS symptoms were significantly more often females, were more often infected by Salmonella than by Campylobacter, had more severe symptoms during the initial infection, and had more often GI symptoms prior to the infection. They reported higher anxiety, depression, and somatisation scores, but were not different with respect to acute stool habits.

CONCLUSIONS & INFERENCES

Nearly 10% of patients with an intestinal bacterial infection report postinfectious symptoms up to 10 years after the infectious event. They represent a clinically important population with high psychiatric comorbidity and somatic symptom burden.

Post-infectious irritable bowel syndrome: the past, the present and the future

BACKGROUND

Irritable bowel syndrome (IBS), once thought to be a psychosomatic disease, is being considered to be more organic. Post-infectious IBS (PI-IBS), defined as acute onset IBS (by Rome criteria) after gastrointestinal infection in an individual without prior IBS with two or more of the followings: fever, vomiting, diarrhea, a positive stool culture. The recent and old literature of PI-IBS will be reviewed. Future directions for research will be presented.

METHODS

Literature on PI-IBS was reviewed by electronic search and cross references of these papers.

RESULTS

Interest in studies on PI-IBS, which was described five to six decades ago, re-surfaced recently. 3.6 to 32% patients with acute gastroenteritis develop PI-IBS during 3-12 month follow-up. PI-IBS is commonly diarrhea predominant. Factors implicated in development include nature of pathogens, duration and severity of diarrhea, younger age, female gender and psychological co-morbidities like anxiety and depression. The pathogenesis of PI-IBS is largely related to continuing gut inflammation due to inability of the host to contain the inflammatory reaction, altered gut microbiota, increased intestinal permeability, muscle hyper-contractility and visceral hypersensitivity. There could be an overlap between PI-IBS and post-infectious malabsorption syndrome (PI-MAS), popularly known as tropical sprue.

CONCLUSIONS

Development of IBS in a subset of patients with acute gastroenteritis is uncontested. This is expected to open a paradigm shift in understanding the pathogenesis of IBS. Future studies should address the issue of overlap of PI-IBS and PI-MAS. Exploring the molecular mechanisms of pathogenesis of PI-IBS may help to design preventive and therapeutic strategies.

Functional gastrointestinal disorders and overlap syndrome in Korea

Functional gastrointestinal disorders (FGIDs) are common in clinical practice and in communities around the world, including Korea. In a recent point prevalence study on functional dyspepsia (FD) in Korea using the Rome III criteria, 13.4% of community respondents reported dyspepsia. Forty-seven percent of these FD cases were classified as postprandial distress syndrome, 26% as epigastric pain syndrome, and 27% as overlap syndrome. Upper and lower GI symptoms commonly overlap and FGIDs are related to psychological disorders. In our recent study of subjects recruited from a health-screening program, the point prevalence of FD, irritable bowel syndrome (IBS), and reflux esophagitis (RE) was 13.2%, 3.9%, and 8.2%, respectively. The odds ratio of having FD and IBS together was estimated to be 4.4 (95% CI: 1.21-15.71). We found a positive relationship between FD and IBS. Recently, several genetic studies have suggested that serotonin transporter (SERT) gene polymorphisms and the G-protein β3 (GNβ3) C825T gene polymorphism are associated with FD and IBS. However, we did not find an association between SERT and GNβ3 C825T genetic polymorphisms and overlap syndrome, including FD and IBS, in our previous study in a Korean population. We therefore undertook a validation study of the Rome III criteria for FGIDs by factor analysis of symptoms. The sensitivity and specificity of Rome III criteria in discriminating FGIDs from organic diseases of the upper GI tract was 60% and 53%, respectively, while the sensitivity and specificity of these criteria for the lower GI tract was 80% and 50%, respectively, partially supporting the use of the Rome III criteria in Korea.

Pathogenic factors involved in the development of irritable bowel syndrome: focus on a microbial role

Irritable bowel syndrome (IBS) is a symptom complex characterized by recurrent abdominal pain or discomfort, and accompanied by abnormal bowel habits, in the absence of any discernible organic abnormality. Its origin remains unclear, partly because multiple pathophysiologic mechanisms are likely to be involved. A significant proportion of patients develop IBS symptoms after an episode of gastrointestinal infection. In addition to gastrointestinal pathogens, recent evidence suggests that patients with IBS have abnormal composition and higher temporal instability of their intestinal microbiota. Because the intestinal microbiota is an important determinant of normal gut function and immunity, this instability may constitute an additional mechanism that leads to symptom generation and IBS. More importantly, a role for altered microbiota composition in IBS raises the possibility of therapeutic interventions through selective antibiotic or probiotic administration. The new concept of functional bowel diseases incorporates the bidirectional communication between the gut and the central nervous system (gut-brain axis), which may explain the multiple facets of IBS by linking emotional and cognitive centers of the brain with peripheral functioning of the gastrointestinal tract and vice versa.

Disease burden of post-infectious irritable bowel syndrome in The Netherlands

Post-infectious irritable bowel syndrome (PI-IBS) has been established as a sequel of infectious intestinal disease (IID). The aim of this study was to estimate the burden of PI-IBS caused by the pathogens Campylobacter, Salmonella and Shigella, and to compare this with other outcomes associated with these pathogens. The attributable risk of PI-IBS due to bacterial pathogens was calculated and linked to national data on gastroenteritis incidence and measures for severity and duration of illness in order to estimate the burden of PI-IBS. One year post-infection, IBS developed in 9% of patients with bacterial IID. The burden of PI-IBS adds over 2300 disability adjusted life years to the total annual disease burden for the selected pathogens. PI-IBS is a frequent sequel of IID, resulting in a considerable disease burden compared to other outcomes. If this relationship is not considered, this will result in an underestimation of the disease burden of IID.

Bugs and irritable bowel syndrome: The good, the bad and the ugly

Recently, there has been strong interest in the therapeutic potential of probiotics for irritable bowel syndrome (IBS). At the same time, there is a rapidly growing body of evidence to support an etiological role for gastrointestinal infection and the associated immune activation in the development of post-infectious IBS. In a more controversial area, small intestinal bacterial overgrowth has been associated with a subset of patients with IBS; the issue of whether it is appropriate to treat a subset of IBS patients with antibiotics and probiotics is currently a matter for debate. Thus, it appears that the gastrointestinal microbial flora may exert beneficial effects for symptoms of IBS under some circumstances, while in other situations gut microbes could give rise to symptoms of IBS. How do we make sense of the apparently diverse roles that 'bugs' may play in IBS? To address this question, we have conducted an in-depth review, attempting where possible to draw lessons from Asian studies.

Advances in the pathogenesis of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a highly prevalent functional gastrointestinal disorder in the world. Although previous studies have led to a greater understanding of the underlying pathophysiology of IBS, the mechanisms underlying the development of IBS are complex and still unclear. It is currently known that a variety of factors contribute to the development of IBS. Abnormal gastrointestinal motility and visceral hypersensitivity are thought to be the pathophysiological basis of the disease. In this article, we will review the recent advances in the pathogenesis of irritable bowel syndrome.

Post-infectious irritable bowel syndrome

Post-infectious irritable bowel syndrome (PI-IBS) is a common disorder wherein symptoms of IBS begin after an episode of acute gastroenteritis. Published studies have reported incidence of PI-IBS to range between 5% and 32%. The mechanisms underlying the development of PI-IBS are not fully understood, but are believed to include persistent sub-clinical inflammation, changes in intestinal permeability and alteration of gut flora. Individual studies have suggested that risk factors for PI-IBS include patients’ demographics, psychological disorders and the severity of enteric illness. However, PI-IBS remains a diagnosis of exclusion with no specific disease markers and, to date, no definitive therapy exists. The prognosis of PI-IBS appears favorable with spontaneous and gradual resolution of symptoms in most patients.