Incidence of post-infectious irritable bowel syndrome and functional intestinal disorders following a water-borne viral gastroenteritis outbreak

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.

Contribution of sex and gender roles to the incidence of post-infectious irritable bowel syndrome in a prospective study

Post-infectious irritable bowel syndrome (PI-IBS) occurs in about 10% of cases following gastroenteritis. The incidence of IBS is higher in females. However, it is not clear whether this is due to biological or psychosocial factors. We aimed to investigate the influence of gender roles on the incidence of PI-IBS, alongside traditional risk factors. Our study included 231 patients diagnosed with gastroenteritis who were hospitalized and treated with antibiotics between 2018 and 2021. The Korean Sex Role Inventory-Short Form (KSRI-SF), based on the Bem Sex Role Inventory (BSRI) was used to categorize patients (androgynous, masculine, feminine, and undifferentiated types). Six months after treatment, we conducted a telephone survey to confirm the presence of PI-IBS using the ROME IV criteria. Among the patients, 43.3% were female, and the mean age was 43.67 ± 16.09 years. After 6 months, 34 patients developed PI-IBS. Univariate analysis revealed that younger age, female sex, KSRI-SF undifferentiated type, and longer duration of antibiotic use independently influenced the occurrence of PI-IBS. Multivariate analysis showed that PI-IBS was associated with the KSRI-SF undifferentiated type and higher C-reactive protein (CRP) levels. Our study showed that the KSRI-SF undifferentiated type and high CRP levels at initial infection were associated with PI-IBS.

Post-infectious irritable bowel syndrome following a diagnosis of traveller's diarrhoea: a comprehensive characterization of clinical and laboratory parameters

BACKGROUND

Prolonged or recurrent gastrointestinal symptoms may persist after acute traveller's diarrhoea (TD), even after adequate treatment of the primary cause. This study aims to describe the epidemiological, clinical and microbiological characteristics of patients with post-infectious irritable bowel syndrome (PI-IBS) after returning from tropical or subtropical areas.

METHODS

We conducted a retrospective study of patients presenting between 2009 and 2018 at the International Health referral centre in Barcelona with persistent gastrointestinal symptoms following a diagnosis of TD. PI-IBS was defined as the presence of persistent or recurrent gastrointestinal manifestations for at least 6 months after the diagnosis of TD, a negative stool culture for bacterial pathogens and a negative ova and parasite exam after targeted treatment. Epidemiological, clinical and microbiological variables were collected.

RESULTS

We identified 669 travellers with a diagnosis of TD. Sixty-eight (10.2%) of these travellers, mean age 33 years and 36 (52.9%) women, developed PI-IBS. The most frequently visited geographical areas were Latin America (29.4%) and the Middle East (17.6%), with a median trip duration of 30 days (IQR 14-96). A microbiological diagnosis of TD was made in 32 of these 68 (47%) patients, 24 (75%) of whom had a parasitic infection, Giardia duodenalis being the most commonly detected parasite (n = 20, 83.3%). The symptoms persisted for a mean of 15 months after diagnosis and treatment of TD. The multivariate analysis revealed that parasitic infections were independent risk factors for PI-IBS (OR 3.0, 95%CI 1.2-7.8). Pre-travel counselling reduced the risk of PI-IBS (OR 0.4, 95%CI 0.2-0.9).

CONCLUSIONS

In our cohort, almost 10% of patients with travellers' diarrhoea developed persistent symptoms compatible with PI-IBS. Parasitic infections, mainly giardiasis, seem to be associated with PI-IBS.

[Diseases of the gastrointestinal tract in the context of COVID-19 infection: present and future challenges: A review]

A significant prevalence of gastrointestinal symptoms in SARS-CoV-2 infection is also associated with its fecal-oral transmission, which leads to a progressive increase in the number of patients with diseases of the esophagus, stomach and intestines. In addition, intestinal infections caused by SARS-CoV-2 may be one of the main causes of functional long-term stress-related gastrointestinal disorders, united in the concept of post-COVID syndrome.

Disorders of gut-brain interaction in post-acute COVID-19 syndrome

The novel coronavirus SARS-CoV-2 is responsible for the devastating pandemic which has caused more than 5 million deaths across the world until today. Apart from causing acute respiratory illness and multiorgan dysfunction, there can be long-term multiorgan sequalae after recovery, which is termed 'long COVID-19' or 'post-acute COVID-19 syndrome'. Little is known about long-term gastrointestinal (GI) consequences, occurrence of post-infection functional gastrointestinal disorders and impact the virus may have on overall intestinal health. In this review, we put forth the various mechanisms which may lead to this entity and possible ways to diagnose and manage this disorder. Hence, making physicians aware of this spectrum of disease is of utmost importance in the present pandemic and this review will help clinicians understand and suspect the occurrence of functional GI disease post recovery from COVID-19 and manage it accordingly, avoiding unnecessary misconceptions and delay in treatment.

Sadness and Anxiety Modify the Relationship Between COVID-19 and Gastrointestinal Symptoms at 6-12 Months of Follow-up

Background and Aims

It is unclear to what degree post-COVID-19 gastrointestinal (GI) symptoms are caused by the SARS-CoV-2 virus vs psychological factors related to the stress of the pandemic. To evaluate this, we compared rates of long-term GI and mental health symptoms in patients testing positive vs negative for SARS-CoV-2.

Methods

Adults presenting for SARS-CoV-2 testing from April to November 2020 were prospectively enrolled in a longitudinal cohort. Six to 12 months later, the presence and severity of current GI and mental health symptoms were assessed on a 5-point Likert scale. A multivariable logistic regression model was used to estimate the odds of a positive COVID test for predicting GI symptoms, stratified by sadness/anxiety.

Results

749 COVID-positive and 107 COVID-negative patients completed the survey. The prevalence of at least one GI symptom was higher in patients with COVID-19 (29 vs 18%, P = .01). However, after stratifying by sadness/anxiety, differences in GI symptoms according to COVID status were no longer significant. On multivariable analysis, the adjusted odds ratio for GI symptoms was 8.26 (95% CI 4.04-16.9) for positive COVID with sadness/anxiety, 8.74 (95% CI 2.63-29.0) for negative COVID with sadness/anxiety, and 1.16 (95% CI 0.57-2.39) for positive COVID without sadness/anxiety, compared to a reference group of negative COVID without sadness/anxiety.

Conclusion

After accounting for sadness and anxiety, there was no association between COVID-19 and the development of long-term GI symptoms. Post-COVID GI symptoms may be mediated bidirectionally through coexisting anxiety and depression, similar to disorders of gut-brain interaction.

Emerging role of the gut microbiome in post-infectious irritable bowel syndrome: A literature review

Post-infectious irritable bowel syndrome (PI-IBS) is a particular type of IBS, with symptom onset after an acute episode of infectious gastroenteritis. Despite infectious disease resolution and clearance of the inciting pathogen agent, 10% of patients will develop PI-IBS. In susceptible individuals, the exposure to pathogenic organisms leads to a marked shift in the gut microbiota with prolonged changes in host-microbiota interactions. These changes can affect the gut-brain axis and the visceral sensitivity, disrupting the intestinal barrier, altering neuromuscular function, triggering persistent low inflammation, and sustaining the onset of IBS symptoms. There is no specific treatment strategy for PI-IBS. Different drug classes can be used to treat PI-IBS similar to patients with IBS in general, guided by their clinical symptoms. This review summarizes the current evidence for microbial dysbiosis in PI-IBS and analyzes the available data regarding the role of the microbiome in mediating the central and peripheral dysfunctions that lead to IBS symptoms. It also discusses the current state of evidence on therapies targeting the microbiome in the management of PI-IBS. The results of microbial modulation strategies used in relieving IBS symptomatology are encouraging. Several studies on PI-IBS animal models reported promising results. However, published data that describe the efficacy and safety of microbial targeted therapy in PI-IBS patients are scarce. Future research is required.

Early symptoms preceding post-infectious irritable bowel syndrome following COVID-19: a retrospective observational study incorporating daily gastrointestinal symptoms

BACKGROUND

Intestinal microinflammation with immune dysfunction due to severe acute respiratory syndrome coronavirus 2 reportedly precipitates post-infectious irritable bowel syndrome. This study aimed to elucidate potential risk factors for subsequent development of irritable bowel syndrome, hypothesizing that it is associated with specific symptoms or patient backgrounds.

METHODS

This single-center retrospective observational study (2020-2021) included adults with confirmed coronavirus disease requiring hospital admission and was conducted using real-world data retrieved from a hospital information system. Patient characteristics and detailed gastrointestinal symptoms were obtained and compared between patients with and without coronavirus disease-induced irritable bowel syndrome. Multivariate logistic models were used to validate the risk of developing irritable bowel syndrome. Moreover, daily gastrointestinal symptoms during hospitalization were examined in patients with irritable bowel syndrome.

RESULTS

Among the 571 eligible patients, 12 (2.1%) were diagnosed with irritable bowel syndrome following coronavirus disease. While nausea and diarrhea during hospitalization, elevated white blood cell count on admission, and intensive care unit admission were associated with the development of irritable bowel syndrome, nausea and diarrhea were identified as risk factors for its development following coronavirus disease, as revealed by the adjusted analyses (odds ratio, 4.00 [1.01-15.84] and 5.64 [1.21-26.31], respectively). Half of the patients with irritable bowel syndrome had both diarrhea and constipation until discharge, and constipation was frequently followed by diarrhea.

CONCLUSIONS

While irritable bowel syndrome was rarely diagnosed following coronavirus disease, nausea and diarrhea during hospitalization precede the early signs of irritable bowel syndrome following coronavirus disease.

[Frequent Gastro-Intestinal Disorders: Management of Functional Dyspepsia and Irritable Bowel Syndrome in Clinical Practice]

Frequent Gastro-Intestinal Disorders: Management of Functional Dyspepsia and Irritable Bowel Syndrome in Clinical Practice Abstract: Functional dyspepsia (FD) and irritable bowel syndrome (IBS), two common gastrointestinal entities with overlapping symptoms, should be diagnosed according to Rome IV criteria. This includes one or more of the following symptoms: in FD, postprandial fullness, early satiation, epigastric pain or burning; in IBS, recurrent abdominal pain associated with defecation, change in frequency of stool or form of stool. To exclude structural diseases, attention should be paid to alarm symptoms. As far as treatment is concerned, a stepwise scheme proves to be effective for both diseases. Step 1: doctor-patient discussion with explanation of diagnosis and prognosis as well as clarification of therapy goals; lifestyle adaptations; use of phytotherapeutics; step 2: symptom-oriented medication: for FD, PPIs or prokinetics; for IBS, antispasmodics, secretagogues, laxatives, bile acid sequestrants, antidiarrheals, antibiotics, probiotics; step 3: visceral analgesics (antidepressants).

Long-term Gastrointestinal Sequelae Following COVID-19: A Prospective Follow-up Cohort Study

BACKGROUND & AIMS

Coronavirus disease 2019 (COVID-19) is associated with long-term gastrointestinal sequelae; however, prospective longitudinal data are sparse. We prospectively studied the frequency, spectrum, and risk factors of post infection functional gastrointestinal disorders/disorders of gut-brain interaction (PI-FGID/DGBI) after COVID-19.

METHODS

Three hundred twenty cases with COVID-19 and 2 control groups, group A, 320 healthy spouses/family controls, and group B, 280 healthy COVID serology-negative controls, were prospectively followed up at 1, 3, and 6 months by using validated Rome IV criteria to evaluate the frequency of PI-FGID/DGBI.

RESULTS

Of 320 cases, at 1 month 36 (11.3%) developed FGID symptoms. Persistent symptoms were noted in 27 (8.4%) at 3 months and in 21 (6.6%) at 6 months. At 3 months, 8 (2.5%) had irritable bowel syndrome, 7 (2.2%) had functional diarrhea, 6 (1.9%) had functional dyspepsia, 3 (0.9%) had functional constipation, 2 (0.6%) had functional dyspepsia-IBS overlap, and 1 (0.3%) had functional abdominal bloating/distention. Among symptomatic individuals at 3 months, 8 (29.6%) were positive for isolated carbohydrate malabsorption, 1 (3.7%) was positive for post infection malabsorption syndrome, and 1 (3.7%) was positive for intestinal methanogen overgrowth. None of the healthy controls developed FGID up to 6 months of follow-up (P < .01). Predictive factors at 3 and 6 months were severity of infection (P < .01) and presence of gastrointestinal symptoms at the time of infection (P < .01).

CONCLUSIONS

COVID-19 led to significantly higher number of new onset PI-FGID/DGBI compared with healthy controls at 3 and 6 months of follow-up. If further investigated, some patients can be diagnosed with underlying malabsorption.

It Ain't Over 'Til It's Over: SARS CoV-2 and Post-infectious Gastrointestinal Dysmotility

The ongoing pandemic resulting from severe acute respiratory syndrome-caused by coronavirus 2 (SARS-CoV-2)-has posed a multitude of healthcare challenges of unprecedented proportions. Intestinal enterocytes have the highest expression of angiotensin-converting enzyme-2 (ACE2), which functions as the key receptor for SARS-CoV-2 entry into cells. As such, particular interest has been accorded to SARS-CoV-2 and how it manifests within the gastrointestinal system. The acute and chronic alimentary clinical implications of infection are yet to be fully elucidated, however, the gastrointestinal consequences from non-SARS-CoV-2 viral GI tract infections, coupled with the generalized nature of late sequelae following COVID-19 disease, would predict that motility disorders are likely to be seen in these patients. Determination of the chronic effects of COVID-19 disease, herein defined as GI disease which is persistent or recurrent more than 3 months following recovery from the acute respiratory illness, will require comprehensive investigations comprising combined endoscopic- and motility-based evaluation. It will be fascinating to ascertain whether the specific post-COVID-19 phenotype is hypotonic or hypertonic in nature and to identify the most vulnerable target portions of the gut. A specific biological hypothesis is that motility disorders may result from SARS-CoV-2-induced angiotensin-converting enzyme 2 (ACE2) depletion. Since SARS-CoV-2 is known to exhibit direct neuronal tropism, the potential also exists for the development of neurogenic motility disorders. This review aims to explore some of the potential pathophysiologic mechanisms underlying motility dysfunction as it relates to ACE2 and thereby aims to provide the foundation for mechanism-based potential therapeutic options.

Association between water source and chronic gastrointestinal diseases in Chinese: A cross-sectional and longitudinal study

Background

Gastrointestinal health is closely associated with the quality of the water supply. However, long-term associations between the water supply type and chronic gastrointestinal disease (CGD) are unclear.

Method

The water supply was categorized as "tap-water" or "non-tap water" use. Changes in water source use were categorized into four types: "non-tap water both at baseline and in follow-ups," "non-tap water at baseline and tap-water in follow-ups," "tap-water at baseline and non-tap water in follow-ups," or "tap-water at baseline and in follow-ups." We explored the association between tap-water use (and changes therein) and the risk of CGD in a cross-sectional and longitudinal population study based on national cohort data from 2011 to 2018.

Results

After the inclusion and exclusion process, 13,332 and 9,688 participants were included in the cross-sectional and longitudinal analyses, respectively. Tap-water use was associated with fewer CGD cases at baseline (OR = 0.98, 95% CI: 0.90, 1.07). Tap-water use at baseline was associated with significantly lower incidence of CGD in follow-ups (HR = 0.70, 95% CI: 0.70, 0.90). Compared with consistent non-tap water use in both baseline and follow-ups, switching from non-tap water to tap-water use in follow-ups was associated with a lower risk of CGD (HR = 0.79, 95% CI: 0.64, 0.97), tap water use at both baseline and in follow-ups was associated with a lower risk of CGD (HR = 0.72, 95% CI: 0.59, 0.88). The decreased risk of CGD followed a linear trend (P _fortrend < 0.01). Adjustment for indoor solid fuel use and outdoor air pollution exposure to PM_2.5 did not change the association between tap water use and CGD.

Conclusion

Tap water use was associated with a reduced risk of incident CGD. The results from this study should aid in effect assessment for water purification strategies and public decision support for gastrointestinal health management.

Gut Non-Bacterial Microbiota: Emerging Link to Irritable Bowel Syndrome

As a common functional gastrointestinal disorder, irritable bowel syndrome (IBS) significantly affects personal health and imposes a substantial economic burden on society, but the current understanding of its occurrence and treatment is still inadequate. Emerging evidence suggests that IBS is associated with gut microbial dysbiosis, but most studies focus on the bacteria and neglect other communities of the microbiota, including fungi, viruses, archaea, and other parasitic microorganisms. This review summarizes the latest findings that link the nonbacterial microbiota with IBS. IBS patients show less fungal and viral diversity but some alterations in mycobiome, virome, and archaeome, such as an increased abundance of Candida albicans. Moreover, fungi and methanogens can aid in diagnosis. Fungi are related to distinct IBS symptoms and induce immune responses, intestinal barrier disruption, and visceral hypersensitivity via specific receptors, cells, and metabolites. Novel therapeutic methods for IBS include fungicides, inhibitors targeting fungal pathogenic pathways, probiotic fungi, prebiotics, and fecal microbiota transplantation. Additionally, viruses, methanogens, and parasitic microorganisms are also involved in the pathophysiology and treatment. Therefore, the gut nonbacterial microbiota is involved in the pathogenesis of IBS, which provides a novel perspective on the noninvasive diagnosis and precise treatment of this disease.

Post-Infectious Irritable Bowel Syndrome after an Epidemic of Gastroenteritis in South of Iran

Background: Irritable bowel syndrome (IBS) is a chronic disabling condition without a well-defined etiology. Infectious gastroenteritis (IGE) has been linked to this syndrome. There are few data from Iran on this association. Methods: In August 2018, an epidemic of IGE caused by Escherichia coli occurred in a village in the west of Shiraz in southern Iran. One year after this epidemic, the occurrence of IBS was surveyed in those who suffered from IGE based on Rome IV criteria in that village. Results: Of 179 patients included in the present study, 17 patients (9.5%) had post-infectious (PI)-IBS. There was no difference in age, sex, antibiotic use, hematochezia, duration of infectious diarrhea, fever, and weight loss at the time of IGE between those with and without PI-IBS. Conclusion: PI-IBS is common after IGE, but no risk factor for its development was found in this study.

Epidemiology, Clinical Features, and Unusual Complications of Norovirus Infection in Taiwan: What We Know after Rotavirus Vaccines

Noroviruses (NoVs) are one of the emerging and rapidly spreading groups of pathogens threatening human health. A reduction in sporadic NoV infections was noted following the start of the COVID-19 pandemic, but the return of NoV gastroenteritis during the COVID-19 pandemic has been noted recently. Research in recent years has shown that different virus strains are associated with different clinical characteristics; moreover, there is a paucity of research into extraintestinal or unusual complications that may be associated with NoV. The genomic diversity of circulating NoVs is also complex and may vary significantly. Therefore, this short narrative review focuses on sharing the Taiwan experience of NoV infection including epidemiology, clinical features, and complications following suboptimal rotavirus immunization in Taiwan (after October 2006). We also highlight the unusual complications associated with NoV infections and the impacts of NoV infection during the COVID-19 pandemic in the literature for possible future research directions. To conclude, further research is needed to quantify the burden of NoV across the spectrum of disease severity in Taiwan. The evidence of the connection between NoV and the unusual complications is still lacking.

Functional gastrointestinal and somatoform symptoms five months after SARS-CoV-2 infection: A controlled cohort study

BACKGROUND

Gastrointestinal infections represent a risk factor for functional gastrointestinal and somatoform extraintestinal disorders. We investigated the prevalence and relative risk (RR) of gastrointestinal and somatoform symptoms 5 months after SARS-CoV-2 infection compared with a control cohort.

METHODS

One hundred and sixty-four SARS-CoV-2 infected patients and 183 controls responded to an online questionnaire about symptoms and signs during the acute phase of the infection and after 4.8 ± 0.3 months. Presence and severity of gastrointestinal symptoms, somatization, anxiety, and depression were recorded with standardized questionnaires. Stool form and presence of irritable bowel syndrome (IBS) were also recorded. Any association between exposure to infection and symptoms was evaluated by calculating crude and adjusted RR values and score differences with 95% confidence intervals (CI).

KEY RESULTS

Fever, dyspnea, loss of smell/taste/weight, diarrhea, myalgia, arthralgia, and asthenia were reported by more than 40% of patients during the acute phase. Compared with controls, adjusted RRs for loose stools, chronic fatigue, and somatization were increased after infection: 1.88 (95% CI 0.99-3.54), 2.24 (95% CI 1.48-3.37), and 3.62 (95% CI 1.01-6.23), respectively. Gastrointestinal sequelae were greater in patients with diarrhea during the acute phase.

CONCLUSIONS & INFERENCES

Mild gastroenterological symptoms persist 5 months after SARS-CoV-2 infection, in particular in patients reporting diarrhea in the acute phase. Infected patients are at increased risk of chronic fatigue and somatoform disorders, thus supporting the hypothesis that both functional gastrointestinal and somatoform disorders may have a common biological origin.

Real-World Evidence for COVID-19 Delta Variant's Effects on the Digestive System and Protection of Inactivated Vaccines from a Medical Center in Yangzhou, China: A Retrospective Observational Study

BACKGROUND

Coronavirus disease 2019 (COVID-19) is rapidly disseminated worldwide, and it continues to threaten global public health. Recently, the Delta variant has emerged as the most dreaded variant worldwide. COVID-19 predominantly affects the respiratory tract, and studies have reported the transient effects of COVID-19 on digestive system function. However, the relationship between the severity of the Delta variant and digestive system function remains to be investigated. Additionally, data on the ability of the inactive Chinese vaccines (Sinovac or Sinopharm) to protect against the Delta variant or COVID-19-induced gastrointestinal symptoms in the real world are insufficient. Thus, the present retrospective observational study first attempted to use the total gastrointestinal symptom rating scale scores (GSRS) to quantify the possible changes in digestive system functions following the Delta variant infection in the early stage. In addition, the study discusses the potential of inactivated vaccines in preventing severe or critical symptoms or Delta variant-induced digestive system dysfunction.

METHODS

To evaluate the difference between mild illness group, moderate illness group, and severe or critical illness group, analysis of variance (ANOVA) was employed to compare the three groups' total gastrointestinal symptom rating scale scores (GSRS). A chi-squared test was used to compare the differences in the ratio of the abnormal biochemical measurements among the three groups first. Then, the percentage of the vaccinated population was compared among the three groups. Additionally, the ratio of the abnormal serum markers between the vaccinated and nonvaccinated cohorts was compared. A P value < 0.05 was considered statistically significant.

RESULTS

Significant differences were observed in the abnormal ratio of alanine aminotransferase (ALT), total bilirubin (TBIL), direct bilirubin (DBIL), lactate dehydrogenase (LDH), and Interleukin 6 (IL-6) ratio among the three groups (P < 0.05). Additionally, no significant difference was observed in the abnormal serum markers ratio between day 14 and day 21 after treatment (P > 0.05). A significant difference was observed in the total GSRS scores among the three groups and the ratio of the vaccinated population among the three groups (P < 0.05). A significant difference was observed in the ratio of the abnormal serum ALT and AST levels between the vaccinated and nonvaccinated cohorts (P < 0.05).

CONCLUSIONS

In summary, serum AST, DBIL, LDH, and IL-6 levels are potential markers for distinguishing severe or critical patients in the early stage of the Delta variant infection. Additionally, changes in the levels of these serum makers are transient, and the levels can return to normal after treatment. Furthermore, severe gastrointestinal discomfort was significantly more prevalent in patients with severe or critical diseases and should thus be considered in patients diagnosed with Delta variant infection. Finally, inactivated vaccines may prevent severe or critical symptoms and Delta variant-induced liver dysfunction. Vaccination programs must be promoted to protect public health.

Norovirus: Facts and Reflections from Past, Present, and Future

Human Norovirus is currently the main viral cause of acute gastroenteritis (AGEs) in most countries worldwide. Nearly 50 years after the discovery of the "Norwalk virus" by Kapikian and colleagues, the scientific and medical community continue to generate new knowledge on the full biological and disease spectrum of Norovirus infection. Nevertheless, several areas remain incompletely understood due to the serious constraints to effectively replicate and propagate the virus. Here, we present a narrated historic perspective and summarize our current knowledge, including insights and reflections on current points of interest for a broad medical community, including clinical and molecular epidemiology, viral-host-microbiota interactions, antivirals, and vaccine prototypes. We also include a reflection on the present and future impacts of the COVID-19 pandemic on Norovirus infection and disease.

COVID-19 as a trigger of irritable bowel syndrome: A review of potential mechanisms

In December 2019 a novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), started spreading from Wuhan city of Chinese Hubei province and rapidly became a global pandemic. Clinical symptoms of the disease range from paucisymptomatic disease to a much more severe disease. Typical symptoms of the initial phase include fever and cough, with possible progression to acute respiratory distress syndrome. Gastrointestinal manifestations such as diarrhoea, vomiting and abdominal pain are reported in a considerable number of affected individuals and may be due to the SARS-CoV-2 tropism for the peptidase angiotensin receptor 2. The intestinal homeostasis and microenvironment appear to play a major role in the pathogenesis of COVID-19 and in the enhancement of the systemic inflammatory responses. Long-term consequences of COVID-19 include respiratory disturbances and other disabling manifestations, such as fatigue and psychological impairment. To date, there is a paucity of data on the gastrointestinal sequelae of SARS-CoV-2 infection. Since COVID-19 can directly or indirectly affect the gut physiology in different ways, it is plausible that functional bowel diseases may occur after the recovery because of potential pathophysiological alterations (dysbiosis, disruption of the intestinal barrier, mucosal microinflammation, post-infectious states, immune dysregulation and psychological stress). In this review we speculate that COVID-19 can trigger irritable bowel syndrome and we discuss the potential mechanisms.

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.

Characteristics and Risk Factors of Post-Infection Irritable Bowel Syndrome After Campylobacter Enteritis

BACKGROUND & AIMS

Campylobacter is the leading cause of bacterial gastroenteritis in the United States. We investigated the prevalence of postinfection irritable bowel syndrome (PI-IBS) in a cohort with culture-confirmed Campylobacter cases; risk factors for PI-IBS based on clinical factors; and shifts in IBS patterns postinfection in patients with pre-existing IBS.

METHODS

The Minnesota Department of Health collects data on symptoms and exposures upon notification of Campylobacter cases. From 2011 through 2019, we sent surveys (the Rome III and IBS symptom severity surveys) to 3586 patients 6 to 9 months after Campylobacter infection. The prevalence of PI-IBS was estimated and risk factors were assessed using multivariable logistic regression.

RESULTS

There were 1667 responders to the survey, 249 of whom had pre-existing IBS. Of the 1418 responders without pre-existing IBS, 301 (21%) subsequently developed IBS. Most of these individuals had IBS-mixed (54%), followed by IBS-diarrhea (38%), and IBS-constipation (6%). The mean IBS symptom severity score was 218 (indicating moderate severity). Female sex, younger age, bloody stools, abdominal cramps, and hospitalization during acute enteritis were associated with increased risk, whereas fever was protective for the development of PI-IBS. Antibiotic use and exposure patterns were similar between PI-IBS and control groups. Among patients with IBS-mixed or IBS-diarrhea before infection, 78% retained their subtypes after infection. In contrast, only 50% of patients with IBS-constipation retained that subtype after infection, whereas 40% transitioned to IBS-mixed. Of patients with pre-existing IBS, 38% had increased frequency of abdominal pain after Campylobacter infection.

CONCLUSIONS

In a cohort of patients with Campylobacter infection in Minnesota, 21% developed PI-IBS; most cases reported mixed IBS or diarrhea of moderate severity. Demographic and clinical factors during acute enterocolitis are associated with PI-IBS development. Campylobacter infection also can result in a switch of a pre-existing IBS phenotype.

Post-infection Irritable Bowel Syndrome

Epidemiologic data support that acute gastrointestinal infection is one of the strongest risk factors for development of irritable bowel syndrome (IBS). Risk of post-infection IBS (PI-IBS) seems to be greater with bacterial and protozoal than viral enterocolitis. Younger individuals, women, and those with severe enterocolitis are more likely to develop PI-IBS. Disease mechanisms in animal models and humans involve chronic perturbation of intestinal microbiome, epithelial and neuronal remodeling, and immune activation. These mechanisms can lead to luminal (increased proteolytic activity, altered bile acid composition) and physiologic (increased permeability, transit changes, and visceral hypersensitivity) alterations that can mediate PI-IBS symptoms.

Viral Acute Gastroenteritis in Special Populations

Viral acute gastroenteritis (AGE) is common and afflicts people of all ages. Nonviral causes of AGE are less common. Norovirus is a leading cause of sporadic cases and outbreaks of AGE across all ages. Universal rotavirus vaccination of infants has reduced frequency and severity of rotavirus AGE cases in children and indirectly reduced cases in older adults. Severe illness is more likely in persons at age extremes or with immunocompromising conditions. Viral causes of AGE can lead to protracted diarrheal illness in immunocompromised persons. Nucleic acid amplification tests are changing diagnostic testing algorithms.

ACG Clinical Guideline: Management of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a highly prevalent, chronic disorder that significantly reduces patients' quality of life. Advances in diagnostic testing and in therapeutic options for patients with IBS led to the development of this first-ever American College of Gastroenterology clinical guideline for the management of IBS using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Twenty-five clinically important questions were assessed after a comprehensive literature search; 9 questions focused on diagnostic testing; 16 questions focused on therapeutic options. Consensus was obtained using a modified Delphi approach, and based on GRADE methodology, we endorse the following: We suggest that a positive diagnostic strategy as compared to a diagnostic strategy of exclusion be used to improve time to initiating appropriate therapy. We suggest that serologic testing be performed to rule out celiac disease in patients with IBS and diarrhea symptoms. We suggest that fecal calprotectin be checked in patients with suspected IBS and diarrhea symptoms to rule out inflammatory bowel disease. We recommend a limited trial of a low fermentable oligosaccharides, disacchardies, monosaccharides, polyols (FODMAP) diet in patients with IBS to improve global symptoms. We recommend the use of chloride channel activators and guanylate cyclase activators to treat global IBS with constipation symptoms. We recommend the use of rifaximin to treat global IBS with diarrhea symptoms. We suggest that gut-directed psychotherapy be used to treat global IBS symptoms. Additional statements and information regarding diagnostic strategies, specific drugs, doses, and duration of therapy can be found in the guideline.

Difficulty in diagnosing mild cases of COVID-19 without respiratory symptoms during the Novel Coronavirus Pandemic: Careful monitoring needed for patients with persistent upper gastrointestinal symptoms

Gastrointestinal symptoms have been reported to occur with COVID infection, and clinicians in COVID-19-endemic areas should suspect COVID-19 infection in patients even if they have no noticeable respiratory symptoms and only gastrointestinal symptoms.

You Talking to Me? Says the Enteric Nervous System (ENS) to the Microbe. How Intestinal Microbes Interact with the ENS

Mammalian organisms form intimate interfaces with commensal and pathogenic gut microorganisms. Increasing evidence suggests a close interaction between gut microorganisms and the enteric nervous system (ENS), as the first interface to the central nervous system. Each microorganism can exert a different effect on the ENS, including phenotypical neuronal changes or the induction of chemical transmitters that interact with ENS neurons. Some pathogenic bacteria take advantage of the ENS to create a more suitable environment for their growth or to promote the effects of their toxins. In addition, some commensal bacteria can affect the central nervous system (CNS) by locally interacting with the ENS. From the current knowledge emerges an interesting field that may shape future concepts on the pathogen-host synergic interaction. The aim of this narrative review is to report the current findings regarding the inter-relationships between bacteria, viruses, and parasites and the ENS.

Global burden of irritable bowel syndrome: trends, predictions and risk factors

Irritable bowel syndrome (IBS) is one of the most common disorders of gut-brain interaction worldwide, defined according to patterns of gastrointestinal symptoms as described by the Rome diagnostic criteria. However, these criteria, developed with reference to research conducted largely in Western populations, might be limited in their applicability to other countries and cultures. Epidemiological data show a wide variation in the prevalence of IBS globally and more rigorous studies are needed to accurately determine any differences that might exist between countries as well as the potential explanations. The effects of IBS on the individual, in terms of their quality of life, and on health-care delivery and society, in terms of economic costs, are considerable. Although the magnitude of these effects seems to be comparable between nations, their precise nature can vary based on the existence of societal and cultural differences. The pathophysiology of IBS is complex and incompletely understood; genetics, diet and the gut microbiome are all recognized risk factors, but the part they play might be influenced by geography and culture, and hence their relative importance might vary between countries. This Review aims to provide an overview of the burden of IBS in a global context, to discuss future implications for the care of people with IBS worldwide, and to identify key areas for further research.

Mechanism of action and therapeutic benefit of rifaximin in patients with irritable bowel syndrome: a narrative review

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder with a multifactorial pathophysiology. The gut microbiota differs between patients with IBS and healthy individuals. After a bout of acute gastroenteritis, postinfection IBS may result in up to approximately 10% of those affected. Small intestinal bacterial overgrowth (SIBO) is more common in patients with IBS than in healthy individuals, and eradication of SIBO with systemic antibiotics has decreased symptoms of IBS in some patients with IBS and SIBO. The nonsystemic (i.e. low oral bioavailability) antibiotic rifaximin is indicated in the United States and Canada for the treatment of adults with IBS with diarrhea (IBS-D). The efficacy and safety of 2-week single and repeat courses of rifaximin have been demonstrated in randomized, placebo-controlled studies of adults with IBS. Rifaximin is widely thought to exert its beneficial clinical effects in IBS-D through manipulation of the gut microbiota. However, current studies indicate that rifaximin induces only modest effects on the gut microbiota of patients with IBS-D, suggesting that the efficacy of rifaximin may involve other mechanisms. Indeed, preclinical data reveal a potential role for rifaximin in the modulation of inflammatory cytokines and intestinal permeability, but these two findings have not yet been examined in the context of clinical studies. The mechanism of action of rifaximin in IBS is likely multifactorial, and further study is needed.

Mucosal Tuft Cell Density Is Increased in Diarrhea-Predominant Irritable Bowel Syndrome Colonic Biopsies

Tuft cells are rare chemosensory sentinels found in the gut epithelium. When triggered by helminth infection, tuft cells secrete interleukin-25 (IL-25) basolaterally and subsequently evoke an immune response. Irritable bowel syndrome (IBS) is a common and heterogeneous disorder characterized by bowel dysfunction and visceral pain sensitivity. Dysfunctional gut-brain communication and immune activation contribute to the pathophysiology of this disorder. The study aims were to investigate changes in tuft cell density in non-post-infectious IBS patients. Immunofluorescent labeling of DCLK1-positive tuft cells was carried out in mucosal biopsies from the distal colons of diarrhea and constipation-predominant IBS patients and healthy controls. Tuft cell numbers were also assessed in animal models. Concentrations of interleukin-25 (IL-25) secreted from colonic biopsies and in plasma samples were analyzed using an immunoassay. The density of tuft cells was increased in diarrhea-but not constipation-predominant IBS patient colonic biopsies. Biopsy secretions and plasma concentrations of IL-25 were elevated in diarrhea-but not constipation-predominant IBS participants. Tuft cell hyperplasia was detected in a rat model of IBS but not in mice exposed to chronic stress. Tuft cell hyperplasia is an innate immune response to helminth exposure. However, the patients with diarrhea-predominant IBS have not reported any incidents of enteric infection. Moreover, rats exhibiting IBS-like symptoms displayed increased tuft cell density but were not exposed to helminths. Our findings suggest that factors other than helminth exposure or chronic stress lead to tuft cell hyperplasia in IBS colonic biopsies.

Norovirus encounters in the gut: multifaceted interactions and disease outcomes

Noroviruses are major causes of gastroenteritis, with epidemic outbreaks occurring frequently. They are an important global health concern, especially for pediatric and immunocompromised populations, and are challenging pathogens to target immunologically due to their rapid rates of genetic and antigenic evolution and failure to stimulate durable protective immunity. In this Review, we summarize our current understanding of norovirus pathogenesis, noting the prominent role of murine norovirus as a small animal model for norovirus research. We highlight intriguing data supporting the possible involvement of norovirus in sequelae including irritable bowel syndrome and inflammatory bowel diseases, and describe the innate and adaptive immune mechanisms involved in control of both human and murine norovirus infection. Furthermore, we discuss the potential implications of recent discoveries regarding norovirus interactions with the gut microbiota, and briefly detail current understanding of noroviral evolution and its influence on viral pathogenesis. Our mechanistic understanding of norovirus pathogenesis continues to improve with increasing availability of powerful model systems, which will ultimately facilitate development of effective preventive and therapeutic approaches for this pathogen.

Microbiota: a novel regulator of pain

Among the various regulators of the nervous system, the gut microbiota has been recently described to have the potential to modulate neuronal cells activation. While bacteria-derived products can induce aversive responses and influence pain perception, recent work suggests that "abnormal" microbiota is associated with neurological diseases such as Alzheimer's, Parkinson's disease or autism spectrum disorder (ASD). Here we review how the gut microbiota modulates afferent sensory neurons function and pain, highlighting the role of the microbiota/gut/brain axis in the control of behaviors and neurological diseases. We outline the changes in gut microbiota, known as dysbiosis, and their influence on painful gastrointestinal disorders. Furthermore, both direct host/microbiota interaction that implicates activation of "pain-sensing" neurons by metabolites, or indirect communication via immune activation is discussed. Finally, treatment options targeting the gut microbiota, including pre- or probiotics, will be proposed. Further studies on microbiota/nervous system interaction should lead to the identification of novel microbial ligands and host receptor-targeted drugs, which could ultimately improve chronic pain management and well-being.

A Review of Guidelines/Guidance from Various Countries Around the World for the Prevention and Management of Travellers' Diarrhoea: A Pharmacist's Perspective

International travel is growing and pharmacists are well placed to provide travel health services for the prevention and management of travellers’ diarrhoea (TD). Legislation changes in many countries has enabled pharmacists to access prescription only medicines and vaccinations to provide advice and over the counter medicines for the prevention and management for travel health services; this makes sense since pharmacies are easily accessible to the public and are the patient’s first port of call in the event of any illness. Currently, whilst many guidelines/guidance exist worldwide for the prevention and management of TD, there is no review that focuses on similarities and differences between these and between guidelines on TD and travel related and non-travel related acute diarrhoea. There is also a lack of publication on legislation and the need for evidence based training for all prescribers to provide travel health services. The aims of this work were to review guidelines/guidance for the prevention and management of TD from across the world which were compared with each other as were the TD guidelines compared to that for travel related and non-travel related acute diarrhoea for similarities and differences, with a focus on any relevant pharmacy legislation, needs assessments and training that may impact upon provision of travel health services by pharmacists focusing mainly on TD in adults. The PubMed, Google Scholar and Cochrane database were used to carry out an online search for publications on TD, acute diarrhoea and the guidance pharmacists have in the prevention and management of diarrhoea. The literature reviewed in this article indicates that where no specific guidelines/guidance existed, some pharmacists used the WHO guidelines (WHO), highlighting a need for local, regional and national evidence based guidelines in these countries.

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.

Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Irritable bowel syndrome (IBS) and other functional bowel disorders (FBDs) are prevalent disorders with altered microbiota. Prebiotics positively augment gut microbiota and may offer therapeutic potential.

OBJECTIVES

The aim of this study was to investigate the effect of prebiotics compared with placebo on global response, gastrointestinal symptoms, quality of life (QoL), and gut microbiota, via systematic review and meta-analysis of randomized controlled trials (RCTs) in adults with IBS and other FBDs.

METHODS

Studies were identified using electronic databases, back-searching reference lists, and hand-searching abstracts. RCTs that compared prebiotics to placebo in adults with IBS or other FBDs were included. Two reviewers independently performed screening, data extraction, and bias assessment. Outcome data were synthesized as ORs, weighted mean differences (WMDs) or standardized mean differences (SMDs) with the use of a random-effects model. Subanalyses were performed for type of FBD and dose, type, and duration of prebiotic.

RESULTS

Searches identified 2332 records, and 11 RCTs were eligible (729 patients). The numbers responding were 52/97 (54%) for prebiotic and 59/94 (63%) for placebo, with no difference between groups (OR: 0.62; 95% CI: 0.07, 5.69; P = 0.67). Similarly, no differences were found for severity of abdominal pain, bloating and flatulence, and QoL score between prebiotics and placebo. However, flatulence severity was improved by prebiotics at doses ≤6 g/d (SMD: -0.35; 95% CI: -0.71, 0.00; P = 0.05) and by non-inulin-type fructan prebiotics (SMD: -0.34; 95% CI: -0.66, -0.01; P = 0.04), while inulin-type fructans worsened flatulence (SMD: 0.85; 95% CI: 0.23, 1.47; P = 0.007). Prebiotics increased absolute abundance of bifidobacteria (WMD: 1.16 log10 copies of the 16S ribosomal RNA gene; 95% CI: 0.06, 2.26; P = 0.04). No studies were at low risk of bias across all bias categories.

CONCLUSIONS

Prebiotics do not improve gastrointestinal symptoms or QoL in patients with IBS or other FBDs, but they do increase bifidobacteria. Variations in prebiotic type and dose impacted symptom improvement or exacerbation. This review was registered at PROSPERO as CRD42017074072.

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.

Estimating the incidence of norovirus acute gastroenteritis among US and European international travelers to areas of moderate to high risk of traveler's diarrhea: a prospective cohort study protocol

Background

Acute gastroenteritis (AGE) is the leading cause of illness among returning travelers seeking medical care. Multiple types of enteric pathogens can cause travel-acquired AGE and, while bacterial pathogens have a predominant role, the importance of viruses, such as norovirus, is increasingly recognized. There is a lack of information on travel-acquired norovirus incidence among symptomatic and asymptomatic individuals irrespective of healthcare-seeking behavior. Our aim is to estimate the incidence of travel-acquired AGE due to norovirus and to characterize the burden of disease among international travelers from the United States and Europe.

Methods

We describe a prospective cohort study implemented in five US and European sites to estimate the role of AGE due to norovirus among adult international travelers. We enrolled individuals aged 18 years and older who are traveling to regions of moderate-high risk of AGE, or via cruise ship with an international port stop, with a trip duration of 3–15 days. The study will generate a wide range of health and travel-related data for pre-, during, and up to 6-months post-travel. We will identify laboratory-confirmed travel-acquired norovirus infections among both symptomatic and asymptomatic individuals from self-collected whole stool samples tested via quantitative RT-PCR. Coinfections will be identified in a subset of travelers with AGE using a multiplex molecular-based assay.

Discussion

This study is unique in design and breadth of data collected. The prospective collection of health and behavioral data, as well as biologic samples from travelers irrespective of symptoms, will provide useful data to better understand the importance of norovirus AGE among international travelers. This study will provide data to estimate the incidence of norovirus infections and AGE and the risk of post-infectious sequelae in the 6-month post-travel period serving as a baseline for future norovirus AGE vaccination studies. This study will contribute valuable information to better understand the role of norovirus in travel-acquired AGE risk and the impact of these infections on a broad set of outcomes.

The possible role of bacteria, viruses, and parasites in initiation and exacerbation of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a prolonged and disabling functional gastrointestinal disorder with the incidence rate of 18% in the world. IBS could seriously affect lifetime of patients and cause high economic burden on the community. The pathophysiology of the IBS is hardly understood, whereas several possible mechanisms, such as visceral hypersensitivity, irregular gut motility, abnormal brain-gut relations, and the role of infectious agents, are implicated in initiation and development of this syndrome. Different studies demonstrated an alteration in B-lymphocytes, mast cells (MC), T-lymphocytes, and cytokine concentrations in intestinal mucosa or systemic circulation that are likely to contribute to the formation of the IBS. Therefore, IBS could be developed in those with genetic predisposition. Infections' role in initiation and exacerbation of IBS has been investigated by quite several clinical studies; moreover, the possible role of some pathogens in development and exacerbation of this disease has been described. It appears that the main obligatory pathogens correspond with the IBS disease, Clostridium difficile, Escherichia coli, Mycobacterium avium subspecies paratuberculosis, Campylobacter concisus, Campylobacter jejuni, Chlamydia trachomatis, Helicobacter pylori, Pseudomonas aeruginosa, Salmonella spp, Shigella spp, and viruses, particularly noroviruses. A number of pathogenic parasites (Blastocystis, Dientamoeba fragilis, and Giardia lamblia) may also be involved in the progression and exacerbation of the disease. Based on the current knowledge, the current study concludes that the most common bacterial, viral, and parasitic pathogens may be involved in the development and progression of IBS.

Intestinal Dysmotility Syndromes following Systemic Infection by Flaviviruses

Although chronic gastrointestinal dysmotility syndromes are a common worldwide health problem, underlying causes for these disorders are poorly understood. We show that flavivirus infection of enteric neurons leads to acute neuronal injury and cell death, inflammation, bowel dilation, and slowing of intestinal transit in mice. Flavivirus-primed CD8⁺ T cells promote these phenotypes, as their absence diminished enteric neuron injury and intestinal transit delays, and their adoptive transfer reestablished dysmotility after flavivirus infection. Remarkably, mice surviving acute flavivirus infection developed chronic gastrointestinal dysmotility that was exacerbated by immunization with an unrelated alphavirus vaccine or exposure to a non-infectious inflammatory stimulus. This model of chronic post-infectious gastrointestinal dysmotility in mice suggests that viral infections with tropism for enteric neurons and the ensuing immune response might contribute to the development of bowel motility disorders in humans. These results suggest an opportunity for unique approaches to diagnosis and therapy of gastrointestinal dysmotility syndromes.

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.

Rifaximin is associated with modest, transient decreases in multiple taxa in the gut microbiota of patients with diarrhoea-predominant irritable bowel syndrome

Rifaximin, a non-systemic antibiotic, is efficacious for the treatment of diarrhoea-predominant irritable bowel syndrome (IBS-D). Given the emerging association between the gut microbiota and IBS, this study examined potential effects of rifaximin on the gastrointestinal microbial community in patients with IBS-D. TARGET 3 was a randomised, double-blind, placebo-controlled, phase 3 study. Patients with IBS-D initially received open-label rifaximin 550 mg 3 times daily (TID) for 2 weeks. Patients who responded to the initial treatment and then relapsed were randomised to receive 2 repeat courses of rifaximin 550 mg TID or placebo for 2 weeks, with each course separated by 10 weeks. Stool samples were collected at the beginning and end of open-label treatment, at the beginning and end of the first double-blind treatment, and at the end of the study. As a secondary analysis to the TARGET 3 trial, the composition and diversity of the gut microbiota were assessed, from a random subset of patients, using variable 4 hypervariable region 16S ribosomal RNA gene sequencing. Samples from 103 patients were included. After open-label rifaximin treatment for 2 weeks, 7 taxa (e.g. Peptostreptococcaceae, Verrucomicrobiaceae, Enterobacteriaceae) had significantly lower relative abundance at a 10% false discovery rate threshold. The effects of rifaximin were generally short-term, as there was little evidence of significantly different changes in taxa relative abundance at the end of the study (up to 46 weeks) versus baseline. The results suggest that rifaximin has a modest, largely transient effect across a broad range of stool microbes. Future research may determine whether the taxa affected by rifaximin are causally linked to IBS-D. ClinicalTrials.gov identifier number: NCT01543178.

Antibiotic resistance in travellers' diarrhoeal disease, an external perspective

BACKGROUND

There are many recommendations on the use of antibiotics for prophylaxis and treatment of travellers' diarrhoea (TD). As pharmacists with a special interest in antimicrobial stewardship, we examine and offer our perspective on advice that is recommended to travellers in terms of prevention, treatment and management of TD with a focus on antibiotic use and resistance.

METHODS

Publications on TD were identified through PubMed, Google Scholar and Cochrane Library databases searches using search terms 'travellers diarrhoea', 'travellers diarrhoea', 'travellers' diarrhoea' 'guidelines', 'expert opinion', 'expert reviews', 'South Asia' and 'South East Asia' (S and SE Asia), 'antibiotics', 'resistance genes', 'travel advice', 'pharmacists', 'guidelines', 'prevention' and 'treatment'. References of articles were also screened for additional relevant studies.

RESULTS

Whilst most guidelines and expert reviews were in agreement with the restricted use of antibiotics unless there was a clinical need, the literature review identified gaps in research into behaviours of travellers regarding non-compliance with the pre-travel advice provided and the need for in depth training and education for all healthcare professionals in providing 'tailored' advice for travellers going to high-risk destinations.

CONCLUSIONS

Travellers should be made aware of the problems of antimicrobial resistance in their destination and home countries and offered alternative forms of prophylaxis for TD. Strategies for prevention of TD, other than the use of antibiotics, also need to be emphasized. All healthcare professionals involved in giving advice about TD should be familiar with the epidemiology of the condition as this will inform responsible behaviours, risk assessment and management strategies in different geographical areas.

Diagnosis and management of inflammatory bowel disease in a harpy eagle (Harpia harpyja) with suspected fenbendazole toxicosis

CASE DESCRIPTION A 14-year-old 4.1-kg (9.02-lb) male harpy eagle (Harpia harpyja) was evaluated because of vomiting, anorexia, lethargy, and weight loss (decrease of 0.35 kg [0.77 lb]) of 4 weeks' duration. The bird had previously been treated orally with fenbendazole after the initial onset of clinical signs. CLINICAL FINDINGS An initial CBC revealed marked heteropenia and anemia, but whole-body contrast-enhanced CT images and other diagnostic test findings were unremarkable. Clinical signs persisted, and additional diagnostic testing failed to reveal the cause. During celiotomy, a biopsy specimen of the duodenum was obtained for histologic examination, which revealed lymphoplasmacytic inflammation, consistent with inflammatory bowel disease (IBD). TREATMENT AND OUTCOME Prior to histopathologic diagnosis of IBD, barium sulfate administered via gavage resulted in a temporary improvement of clinical signs. Following diagnosis of IBD, corticosteroid administration was initiated in conjunction with antifungal prophylaxis. Cessation of vomiting and a return to normal appetite occurred within 3 days. Fifteen months after cessation of corticosteroid treatment, the eagle continued to do well. CLINICAL RELEVANCE To our knowledge, this was the first report of diagnosis and management of IBD in an avian species. For the eagle of the present report, results of several diagnostic tests increased clinical suspicion of IBD, but histologic examination of an intestinal biopsy specimen was required for definitive diagnosis. Although successful in this case, steroid administration in avian species must be carefully considered. Conclusive evidence of fenbendazole toxicosis was not obtained, although it was highly suspected in this bird.

A Novel Prebiotic Blend Product Prevents Irritable Bowel Syndrome in Mice by Improving Gut Microbiota and Modulating Immune Response

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder yet it still lacks effective prevention therapies. The aim of this study is to determine whether a novel prebiotic blend (PB) composed of fructo-oligosaccharide (FOS), galactooligosaccharide (GOS), inulin and anthocyanins could be effective in preventing the development of IBS. We explored the possible mechanisms both in animal and in cells. Post-infectious IBS models in C57BL/6 mice were established and were pretreated with the PB, PB and probiotic strains 8 weeks in advance of infection. Eight weeks after infection, intestinal tissues were collected for assessing histomorphology, visceral sensitivity, barrier function, pro-inflammatory cytokines expression and proteomics analysis. Fecal samples were also collected for microbiota analysis. The pro-inflammatory cytokines expression in Caco-2 cells were evaluated after co-incubation with PB and Salmonella typhimurium 14028. The results showed that PB significantly decreased the pro-inflammatory cytokines both in infected Caco-2 cells and PI-IBS models. The loss of body weight, decreased expression of tight junction protein Occludin (OCLN), and changes of the microbiota composition induced by infections could be greatly improved by PB intervention (p < 0.05). The proteomics analysis revealed that this function was associated with Peroxisome proliferator-activated receptor (PPAR)γ pathway.

Prospective cohort study to investigate the burden and transmission of acute gastroenteritis in care homes: a study protocol

INTRODUCTION

Noroviruses are the leading cause of acute gastroenteritis in all age groups, but illness is more severe and causes excess mortality in the elderly, particularly those in long-term care. The total burden of norovirus disease in the elderly in the UK is poorly defined; no current surveillance programmes systematically or accurately quantify norovirus infection in those living in care homes. The aim of this study is to evaluate an enhanced surveillance system for acute gastroenteritis among the elderly in care homes.

METHODS AND ANALYSIS

We will conduct this prospective cohort study in care homes in North West England; residents and staff at study care homes will be asked to participate. We will prospectively enrol a cohort of participants in an enhanced surveillance system to capture the incidence of acute gastroenteritis and use multiplex PCR to detect pathogens. We will sample symptomatic and non-symptomatic participants to understand characteristics of norovirus disease and susceptibility to infection. We will generate novel data on transmission dynamics by collecting data on the pattern of interactions within care homes using electronic proximity sensors. Comparisons of outbreak and non-outbreak periods will be used to quantify the impact of norovirus outbreaks on care homes.

ETHICS AND DISSEMINATION

The study has been approved by the North West-Greater Manchester South NHS Research Ethics Committee (REC Reference: 16/NW/0541). Study outputs will be disseminated through scientific conferences and peer-reviewed publications. This study will provide detailed insight on the burden and aetiology of acute gastroenteritis in care homes, in addition to generating novel data on transmission dynamics and risks. The study will identify areas for improving infection control practice and allow more accurate modelling of the introduction of interventions such as vaccination.

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.

Chronic Norovirus Infection as a Risk Factor for Secondary Lactose Maldigestion in Renal Transplant Recipients: A Prospective Parallel Cohort Pilot Study

BACKGROUND

Chronic norovirus infection is an emerging challenge in the immunocompromised host, in whom it may be asymptomatic or present as chronic diarrhea. The mechanisms of diarrhea in chronic norovirus infection are not well understood, but in analogy to Gardia lamblia and rotavirus infections, secondary lactose maldigestion (LM) might be implicated.

METHODS

Adult renal transplant recipients who had symptomatic chronic norovirus infection with diarrhea were asked to participate in this prospective parallel cohort study. Renal transplant recipients with otherwise unexplainable chronic diarrhea but absent infection served as control group. In both groups, a lactose hydrogen breath test and a lactose tolerance test were performed after exclusion of primary LM by a negative lactase gene test.

RESULTS

Of approximately 800 patients in the cohort of renal transplant recipients at our institution, 15 subjects were included in the present study. Of these, 7 had chronic symptomatic norovirus infection with diarrhea (noro group), and 8 had diarrhea in the absence of norovirus (control group). Lactose hydrogen breath test and lactose tolerance test were positive in all 7 patients (100%) in the noro group, whereas only 1 (12.5%) of 8 patients in the control group had a positive test. Thus, secondary LM was highly prevalent in the noro compared with the control group with an odds ratio of 75.0 (95% confidence interval, 2.6-2153, P = 0.01).

CONCLUSIONS

This is the first report showing a positive association of chronic norovirus infection and secondary LM. Further studies with larger patient numbers and longer follow-up are needed to test a causative relationship between both entities.

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.