Sleep duration prior to an enterotoxigenic Escherichia coli challenge predicts diarrhea severity during infection

BACKGROUND

Acute diarrhea is the most frequent diagnosis among ill travelers. Sleep loss may weaken the body's defense against pathogens and increase susceptibility to infection. The relationship between sleep and infectious diarrhea has not been studied and was assessed utilizing data from a controlled human infection model (CHIM) for enterotoxigenic Escherichia coli (ETEC).

METHODS

During a CHIM assessing the efficacy of an immunoprophylactic targeting ETEC against moderate-to-severe diarrhea (MSD) following challenge, we measured sleep via actigraphy over an 8-day inpatient period. We hypothesized better sleep pre-challenge would predict illness symptomatology following challenge.

RESULTS

Among 57 participants (aged 34.4 ± 8.1 years, 64% male), there was no relationship between sleep metrics and incidence of MSD. However, longer total sleep time the night preceding ETEC challenge was associated with lower maximum 24 h diarrhea volume (B = -1.80, p = 0.01) and total diarrhea volume (B = -2.45, p = 0.01).

CONCLUSIONS

This novel study showed that shorter sleep duration predicted diarrhea severity over the course of an ETEC infection. Future work should experimentally manipulate sleep to further clarify its impact on diarrhea-related outcomes for ETEC and other important enteric pathogens.

Plasma and cerebrospinal fluid concentrations of cefiderocol during successful treatment of carbapenem-resistant Acinetobacter baumannii meningitis

Background

To date, no real-world data are available to describe cefiderocol use in carbapenem-resistant Acinetobacter baumannii (CRAB) meningitis. Furthermore, cefiderocol pharmacokinetic (PK) data to support CNS penetration in human subjects are limited. These gaps pose a significant concern for clinicians who are faced with treating such infections when considering cefiderocol use.

Objectives

To describe cefiderocol CSF and plasma PK and pharmacodynamic (PD) data from two different dosing regimens [2 g IV q6h (regimen 1) and 2 g IV q8h (regimen 2)] during treatment of CRAB meningitis.

Patients and methods

A 61-year-old woman with CRAB meningitis was treated with cefiderocol and intraventricular gentamicin. Steady-state plasma and CSF cefiderocol concentrations were evaluated on Day 19 (regimen 1) and Day 24 (regimen 2) during the cefiderocol treatment course.

Results

CSF AUC was 146.49 and 118.28 mg·h/L, as determined by the linear-log trapezoidal method for regimens 1 and 2, respectively. Penetration into CSF estimated as the AUCCSF/AUCfree plasma ratio was 68% and 60% for regimens 1 and 2, respectively. Estimated free plasma and CSF concentrations exceeded the MIC of the isolate for 100% of the dosing interval. Microbiological and clinical cure were achieved, and no cefiderocol-associated adverse effects were observed.

Conclusions

Cefiderocol, when given as 2 g q8h and 2 g q6h, attained CSF concentrations that exceeded the organism-specific MIC and the CLSI susceptible breakpoint (≤4 mg/L) for 100% of the dosing interval.

A site assessment tool for inpatient controlled human infection models for enteric disease pathogens

The use of the controlled human infection model to facilitate product development and to advance understanding of host-pathogen interactions is of increasing interest. While administering a virulent (or infective) organism to a susceptible host necessitates an ongoing evaluation of safety and ethical considerations, a central theme in conducting these studies in a safe and ethical manner that yields actionable data is their conduct in facilities well-suited to address their unique attributes. To that end, we have developed a framework for evaluating potential sites in which to conduct inpatient enteric controlled human infection model to ensure consistency and increase the likelihood of success.

632. A Randomized, Placebo-Controlled, Double-Blind, Clinical Trial Evaluating Two Dose Regimens of Rifaximin (550mg daily or twice-daily) for Chemoprophylaxis Against Travelers’ Diarrhea Among Deployed U.S. and U.K. Military Personnel (PREVENT TD)

Background

Travelers’ diarrhea (TD) is a leading threat to military readiness. Most trials of rifaximin chemoprophylaxis involve civilians or short-duration travel, whereas military travelers are exposed for longer periods at austere locations and are often physically taxed. We sought to assess efficacy of two regimens among military personnel deployed overseas.

Methods

This was a multi-site, double-blind, placebo-controlled trial of deployed military, randomized to placebo, rifaximin 550 mg daily, or rifaximin 550 mg twice-daily, for up to 42 days (1:1:1; 6 randomizations/block). Diaries were reviewed with subjects on return. Primary endpoint was time to first unformed stool (TFUS) in a TD episode. Other endpoints were assessed by intention to treat (ITT) and subgroups included incidence of any loose stool, meeting criteria for TD, safety, efficacy, adherence and impact to activity endpoints.

Results

343 subjects were included in the ITT population. All UK travelers deployed to a single-site in Kenya; US travelers mostly deployed to various Asia-Pacific locations. Of 73 (21.2%) subjects reporting diarrhea, 42 (57.5%) met TD criteria. Among rifaximin-treated subjects, 15.9% (n=17) reported diarrhea in the twice-daily arm, 20.7% (n=25) in the daily arm, vs. 27.0% (n=31) of placebo recipients; p=.04 and 0.26 respectively. TD was reported by 10.3% (n=11) and 10.7% (n=13) in the daily and twice-daily arms, vs. 15.7% (n=18) among placebo recipients; p=0.24 vs. 0.26 respectively. Among UK personnel, a twice-daily regimen vs. placebo resulted in significantly fewer TD episodes (1.6% vs. 11.9%; p=0.03). Adverse events were similar between groups.

Table 1: Demographics, endpoints, and adverse events (Comparisons are across placebo vs. each dosing regimen. Intent-to-treat [ITT] population defined as subjects enrolled into the study, randomized, travelled and had follow-up. p-values calculated from chi-square or Fisher’s exact test [categorical variables] and Wilcoxon-Mann-Whitney test [continuous variables]. Analyses performed on SAS v9.4. BID: twice-daily)

Conclusion

This is the first trial comparing two high-dose regimens of rifaximin prophylaxis in deployed personnel. Unlike prior reports, neither regimen was associated with an overall significant decrease in TD, potentially due to low overall TD incidence. However, the twice-daily regimen was associated with a numerically lower incidence of diarrheal stool, and in the UK subject group, there was a significant decrease of both TD and diarrheal stool. The impact of variability in regional TD risk, pathogen distribution and adherence in austere deployment environments on efficacy will be reviewed.

Disclosures

All Authors: No reported disclosures

Refinement of the CS6-expressing enterotoxigenic Escherichia coli strain B7A human challenge model: A randomized trial

Background

Human challenge models for enterotoxigenic Escherichia coli (ETEC) facilitate vaccine down-selection. The B7A (O148:H28 CS6⁺LT⁺ST⁺) strain is important for vaccine development. We sought to refine the B7A model by identifying a dose and fasting regimen consistently inducing moderate-severe diarrhea.

Methods

An initial cohort of 28 subjects was randomized (1:1:1:1) to receive B7A following an overnight fast at doses of 10⁸ or 10⁹ colony forming units (cfu) or a 90-minute fast at doses of 10⁹ or 10¹⁰ cfu. A second cohort included naïve and rechallenged subjects who had moderate-severe diarrhea and were given the target regimen. Immune responses to important ETEC antigens were assessed.

Results

Among subjects receiving 10⁸ cfu of B7A, overnight fast, or 10⁹ cfu, 90-minute fast, 42.9% (3/7) had moderate-severe diarrhea. Higher attack rates (71.4%; 5/7) occurred in subjects receiving 10⁹ cfu, overnight fast, or 10¹⁰ cfu, 90-minute fast. Upon rechallenge with 10⁹ cfu of B7A, overnight fast, 5/11 (45.5%) had moderate-severe diarrhea; the attack rate among concurrently challenge naïve subjects was 57.9% (11/19). Anti-CS6, O148 LPS and LT responses were modest across all groups.

Conclusions

An overnight fast enabled a reduction in the B7A inoculum dose; however, the attack rate was inconsistent and protection upon rechallenge was minimal.

Oral delivery of Hyperimmune bovine serum antibodies against CS6-expressing enterotoxigenic Escherichia coli as a prophylactic against diarrhea

BACKGROUND

. Oral administration of bovine antibodies active against enterotoxigenic Escherichia coli (ETEC) have demonstrated safety and efficacy against diarrhea in human challenge trials. The efficacy of bovine serum immunoglobulins (BSIgG) against recombinant colonization factor CS6 or whole cell ETEC strain B7A was assessed against challenge with the CS6-expressing B7A.

METHODS

. This was a randomized, double-blind, placebo-controlled trial in which healthy adults received oral hyperimmune BSIgG anti-CS6, anti-B7A whole cell killed or non-hyperimmune BSIgG (placebo) in a 1:1:1 ratio then challenged with ETEC B7A. Two days pre-challenge, volunteers began a thrice daily, seven day course of immunoprophylaxis. On day 3, subjects received 1 × 10¹⁰ CFUs of B7A. Subjects were observed for safety and the primary endpoint of moderate-severe diarrhea (MSD).

RESULTS

. A total of 59 volunteers received product and underwent ETEC challenge. The BSIgG products were well-tolerated across all subjects. Upon challenge, 14/20 (70%) placebo recipients developed MSD, compared to 12/19 (63%; p = .74) receiving anti-CS6 BSIgG and 7/20 (35%; p = .06) receiving anti-B7A BSIgG. Immune responses to the ETEC infection were modest across all groups.

CONCLUSIONS

. Bovine-derived serum antibodies appear safe and well tolerated. Antibodies derived from cattle immunized with whole cell B7A provided 50% protection against MSD following B7A challenge; however, no protection was observed in subjects receiving serum antibodies targeting CS6. The lack of observed efficacy in this group may be due to low CS6 surface expression on B7A, the high dose challenge inoculum and/or the use of serum derived antibodies versus colostrum-derived antibodies.

Epidemiology and associated microbiota changes in deployed military personnel at high risk of traveler's diarrhea

Travelers’ diarrhea (TD) is the most prevalent illness encountered by deployed military personnel and has a major impact on military operations, from reduced job performance to lost duty days. Frequently, the etiology of TD is unknown and, with underreporting of cases, it is difficult to accurately assess its impact. An increasing number of ailments include an altered or aberrant gut microbiome. To better understand the relationships between long-term deployments and TD, we studied military personnel during two nine-month deployment cycles in 2015–2016 to Honduras. To collect data on the prevalence of diarrhea and impact on duty, a total of 1173 personnel completed questionnaires at the end of their deployment. 56.7% reported reduced performance and 21.1% reported lost duty days. We conducted a passive surveillance study of all cases of diarrhea reporting to the medical unit with 152 total cases and a similar pattern of etiology. Enteroaggregative E. coli (EAEC, 52/152), enterotoxigenic E. coli (ETEC, 50/152), and enteropathogenic E. coli (EPEC, 35/152) were the most prevalent pathogens detected. An active longitudinal surveillance of 67 subjects also identified diarrheagenic E. coli as the primary etiology (7/16 EPEC, 7/16 EAEC, and 6/16 ETEC). Eleven subjects were recruited into a nested longitudinal substudy to examine gut microbiome changes associated with deployment. A 16S rRNA amplicon survey of fecal samples showed differentially abundant baseline taxa for subjects who contracted TD versus those who did not, as well as detection of taxa positively associated with self-reported gastrointestinal distress. Disrupted microbiota was also qualitatively observable for weeks preceding and following the incidents of TD. These findings illustrate the complex etiology of diarrhea amongst military personnel in deployed settings and its impacts on job performance. Potential factors of resistance or susceptibility can provide a foundation for future clinical trials to evaluate prevention and treatment strategies.

Diarrhea and associated illness characteristics and risk factors among British active duty service members at Askari Storm training exercise, Nanyuki, Kenya, January-June 2014

Travelers' diarrhea (TD) has historically been common among deployed military personnel and remains a leading infectious disease threat to this population. The risk factors, work performance, and illness associated with TD among British active duty service members exercising at British Army Training Unit Kenya (BATUK) were assessed. Members of the British Army who were finishing a 6-week combined arms training exercise in Nanyuki, Kenya, completed routine public health surveillance questionnaires. Survey data included information on demographics, rank, risk factors, illness characteristics, and impact on work performance. Among 1,227 survey respondents, 21.9% (n=269) reported having diarrhea, with an estimated 824 days of total missed work and 1,215 days of work underperformance. The majority of cases (54.6%) had multiple diarrheal episodes. One quarter (24.9%) of the respondents with TD sought medical care and 19.7% were bedded down because of their illness. There were no statistically significant differences between the TD and no TD groups on the demographic characteristics examined. The strongest risk factor for diarrhea was having a colleague with diarrhea (adjusted odds ratio=51.78; 95% confidence interval: 29.44-91.06). TD had a notable impact on duty status and operational capability. Efforts are needed to improve BATUK's participant education on the importance of diarrheal disease prevention and management.

Deployment Infectious Disease Threats: IDCRP Initiatives and Vision Forward

BACKGROUND

Infectious diseases pose a significant threat to health and readiness of military personnel deployed globally during wartime and peacekeeping activities. Surveillance and improvement in mitigation through research of infectious disease threats remain an integral part of Force Health Protection. Herein, we review research efforts of the Infectious Disease Clinical Research Program related to deployment and travel-related infections.

METHODS

The objectives of the Deployment and Travel-Related Infections Research Area are to (1) provide epidemiologic and clinical data, including pathogen-specific estimates of disease incidence among deployed troops, (2) execute clinical trials and effectiveness studies to improve recommendations regarding prevention and treatment of infections during deployment, and (3) evaluate the knowledge and practice patterns of health care providers engaged in deployment/travel medicine and the impact on outcomes. The centerpiece protocol of the research area is the Deployment and Travel-Related Infectious Disease Risk Assessment, Outcomes, and Prevention Strategies cohort study (TravMil), which was initiated in 2010 and collects data on a broad range of deployment-related infections.

RESULTS

To date, 4,154 deployed military personnel and traveling Department of Defense (DoD) beneficiaries have been enrolled in TravMil. Surveillance data collected through the TravMil study provide assessment of deployment and travel-related infectious disease threats, and the effectiveness of mitigation strategies. The incidence of travelers' diarrhea, influenza-like illness, and undifferentiated febrile illness is 20.48%, 9.34%, and 6.16%, respectively. The cohort study also provides necessary infrastructure to execute clinical trials. The TrEAT TD clinical trial evaluated the effectiveness of single-dose antibiotic therapy for travelers' diarrhea in the deployed setting. When compared to levofloxacin, azithromycin was not inferior; however, inferiority was not demonstrated with use of single dose of rifaximin. The trial findings supported the development of a deployment-related health guideline for the management of acute diarrheal disease. A clinical trial evaluating the effectiveness of rifaximin for prevention for travelers' diarrhea (Prevent TD) is underway.

CONCLUSIONS

The research area has proven its ability to conduct impactful research, including the development of field-expedient diagnostics, the largest DoD multi-site travelers' diarrhea randomized control trial in peacetime and combat settings, and informed Force Health Protection guidance. The research area continues to provide surveillance data to military commands via an established collaborative network of military treatment facilities, DoD laboratories (both within and outside the continental United States), foreign militaries, and academia. The conduct of clinical and translational research in a deployment setting presents significant challenges, most notably in recruitment/enrollment and compliance with study-related procedures during deployment.

Serum Biomarkers Identify Patients Who Will Develop Inflammatory Bowel Diseases Up to 5 Years Before Diagnosis

BACKGROUND & AIMS

Biomarkers are needed to identify patients at risk for development of inflammatory bowel diseases. We aimed to identify serum biomarkers of Crohn's disease and ulcerative colitis that can be detected and quantified before diagnosis.

METHODS

We obtained serum samples from patients archived before a diagnosis of Crohn's disease (n = 200) or ulcerative colitis (n = 199), as well as from 200 healthy individuals (controls), collected from 1998 through 2013 as part of the US Defense Medical Surveillance System. We measured levels of antibodies against microbes (anti-Saccharomyces cerevisiae IgA or IgG, anti-Escherichiacoli outer membrane porin C, anti-CBir1, anti-flagellin 2, anti-flagellin X, and perinuclear anti-neutrophil cytoplasmic antibodies) and 1129 proteins in each sample. We then used functional principal component analysis to derive the time-varying trajectory for each marker, which then was used in a multivariate model to predict disease status. Predictive performances at different prediagnosis timepoints were evaluated using area under the receiver operating characteristic curves (AUROCs). Biological pathways that were up-regulated in serum from patients with Crohn's disease were identified based on changes in protein abundance at different time periods preceding diagnosis.

RESULTS

We identified a panel of 51 protein biomarkers that were predictive of Crohn's disease within 5 years with an AUROC of 0.76 and a diagnosis within 1 year with an AUROC of 0.87. Based on the proteins included in the panel, imminent development of CD was associated with changes in the complement cascade, lysosomes, innate immune response, and glycosaminoglycan metabolism. Serum antibodies and proteins identified patients who received a diagnosis of ulcerative colitis within 5 years with an AUROC of only 0.56 and within 1 year with an AUROC of 0.72.

CONCLUSIONS

We identified a panel of serum antibodies and proteins that were predictive of patients who will receive a diagnosis of Crohn's disease within 5 years with high accuracy. By contrast we did not identify biomarkers associated with future diagnosis of ulcerative colitis.

1028 Sleep and Enteric Disease: Sleep Now for Less Diarrhea Later

Introduction

The bi-directional relationship between sleep and immune function is well-established. Sufficient sleep supports immune health and can increase vaccine efficacy. Conversely, sickness can disturb sleep quality, which can delay recovery and waking functioning. However, the bidirectional relationship between sleep and infectious diarrhea, the leading infectious disease threat to deployed military populations, has not been studied. We assessed the bi-directional relationship between sleep and enteric disease utilizing data from a recently-completed controlled human infection model (CHIM) with enterotoxigenic Escherichia coli (ETEC).

Methods

During a CHIM to assess the efficacy of an immunoprophylactic targeting ETEC (NCT03040687), we measured sleep via actigraphy over an 8-day inpatient period. Participants ingested prophylaxis 3 times/day during days -2 and -1 and ingested ETEC on day 0. The primary outcome was moderate-severe diarrhea following the ETEC challenge. We hypothesized better sleep pre-challenge would reduce risk of disease after the challenge (assessed using linear regression). We also hypothesized total sleep time (TST) and sleep efficiency (SE) after the challenge would be lower/poorer than baseline (assessed using paired t-test).

Results

Among 59 participants (aged 34.4±8.1yrs, 64% female), longer TST the night preceding ETEC challenge was associated with lower total diarrhea volume (B=-3.13,p=.001). SE was slightly but significantly poorer after the challenge (78 vs. 76%; t(55)=2.2,p=.03), but there was no significant change in TST, potentially due to low TST pre-challenge (316 vs. 329 minutes; p=0.12).

Conclusion

These results - in aggregation with previous work on sleep and vaccines - suggest military sleep regulations should be put in place to increase sleep prior to traveling to an area of responsibility with high risk for enteric disease. These minor behavioral changes could provide lasting benefits to readiness of military servicemembers.

Support

This work was supported by Joint Warfighter Medical Research Program (JWMRP) and the Military Operational Medicine Research Program (MOMRP). The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the US Army or of the US Department of Defense. This abstract has been approved for public release with unlimited distribution.

Rifaximin Fails to Prevent Campylobacteriosis in the Human Challenge Model: A Randomized, Double-Blind, Placebo-Controlled Trial

Background

Campylobacter species are a leading cause of diarrheal disease globally with significant morbidity. Primary prevention efforts have yielded limited results. Rifaximin chemoprophylaxis decreases rates of travelers' diarrhea and may be suitable for high-risk persons. We assessed the efficacy of rifaximin in the controlled human infection model for Campylobacter jejuni.

Methods

Twenty-eight subjects were admitted to an inpatient facility and randomized to a twice-daily dose of 550 mg rifaximin or placebo. The following day, subjects ingested 1.7 × 105 colony-forming units of C. jejuni strain CG8421. Subjects continued prophylaxis for 3 additional days, were followed for campylobacteriosis for 144 hours, and were subsequently treated with azithromycin and ciprofloxacin. Samples were collected to assess immunologic responses to CG8421.

Results

There was no difference (P = 1.0) in the frequency of campylobacteriosis in those receiving rifaximin (86.7%) or placebo (84.6%). Additionally, there were no differences in the clinical signs and symptoms of C. jejuni infection to include abdominal pain/cramps (P = 1.0), nausea (P = 1.0), vomiting (P = .2), or fever (P = 1.0) across study groups. Immune responses to the CG8421 strain were comparable across treatment groups.

Conclusions

Rifaximin did not prevent campylobacteriosis in this controlled human infection model. Given the morbidity associated with Campylobacter infection, primary prevention efforts remain a significant need.

Clinical Trials Registration

NCT02280044.

Cohort profile of the PRoteomic Evaluation and Discovery in an IBD Cohort of Tri-service Subjects (PREDICTS) study: Rationale, organization, design, and baseline characteristics

Purpose

The etiology of Inflammatory Bowel Disease (IBD) remains currently unknown but evidence would suggest that it results from a complex interplay between genetic susceptibility genes, the intestinal microbiome and the environment, resulting in an increased response towards microbial and self-antigens, followed by the development of pre-clinical intestinal inflammation as a precursor to overt clinical disease. Efforts are needed to provide insights into the characterization of the disease, the possible prediction of complications, and the detection of a pre-clinical disease state where, through early screening and intervention, disease course can be reversed, attenuated or even prevented. A consortium of academic, industry and governmental organization investigators initiated this study to enable an assessment of pre-disease biomarkers in patients newly diagnosed with Crohn's disease (CD) and ulcerative colitis (UC).

Participants

A retrospective cohort of 1000 UC and 1000 CD cases with 500 matched controls was drawn from an active duty US military personnel population with relevant inclusion criteria with three associated pre-disease and a single disease-associated archived serum samples.

Findings to date

The PREDICTS study has been established as a biorepository platform study to perform novel discovery and analysis efforts in the field of IBD and proteomic systems biology.

Future plans

This study is poised to enable the assessment of novel biomarkers within the serum compartment to be analyzed with the goal of identifying pre-disease signals that ultimately predict disease risk, and further elucidate disease pathogenesis in the early stages of the disease process, and identify novel exposures that increase disease risk.

1104. Deployment-Associated Infectious Gastroenteritis and Associations With Irritable Bowel Syndrome, Post-Traumatic Stress Disorder, and Combat Stress: A Retrospective Cohort Study Among Deployed United States Military Personnel

Background

Previous studies have shown an association between post-traumatic stress disorder (PTSD) and the development of irritable bowel syndrome (IBS) in deployed service members. Deployment places soldiers at risk for chemical, physical, psychological, and infectious stressors. Acute stress can alter the gastrointestinal barrier leading to gut barrier dysfunction, which is an independent risk factor for infectious gastroenteritis (IGE). We sought to assess if there was an association between IBS and PTSD in military deployed in support of recent and ongoing military operations.

Methods

We conducted a retrospective cohort study of United States service members who participated in a combat deployment to the Middle East from 2001 to 2013 with no prior Axis I disorders or PTSD diagnoses based on data from the Defense Medical Surveillance System. Univariate and multivariate logistic regression models were used to assess the differential risk of PTSD following a combat deployment among those with and without a predeployment diagnosis of IBS. These models were controlled for confounders/covariates of interest (IGE, age, duration of deployment, sex, race, marital status, education level, military rank, branch of service, number of deployments).

Results

Among the 3825 subjects, those who developed IGE had a 34% (P = 0.02) increased risk of PTSD compared with those with no IGE during deployment. Additionally, those with IBS predeployment had a 40% (P = 0.001) increased risk of PTSD upon return from deployment compared with those without IBS predeployment. Duration of deployment was significantly (P < 0.0001) associated with PTSD with an increasing risk with increasing duration of deployment.

Conclusion

IGE and IBS were significantly associated with PTSD further supporting previous studies describing their association. Baseline chronic dysbiosis and acute stress-related microbiota perturbations may lead to short- and long-term resilience and performance deficits in our soldiers that may compromise mission capabilities and decrease the quality of life in returning soldiers. Further understanding the potential interactions between the gut–brain–microbiome may have immediate and long-term impacts on improving warfighter health and performance.

Disclosures

All authors: No reported disclosures.

Trial Evaluating Ambulatory Therapy of Travelers' Diarrhea (TrEAT TD) Study: A Randomized Controlled Trial Comparing 3 Single-Dose Antibiotic Regimens With Loperamide

Background

Recommended treatment for travelers' diarrhea includes the combination of an antibiotic, usually a fluoroquinolone or azithromycin, and loperamide for rapid resolution of symptoms. However, adverse events, postdose nausea with high-dose azithromycin, effectiveness of single-dose rifaximin, and emerging resistance to front-line agents are evidence gaps underlying current recommendations.

Methods

A randomized, double-blind trial was conducted in 4 countries (Afghanistan, Djibouti, Kenya, and Honduras) between September 2012 and July 2015. US and UK service members with acute watery diarrhea were randomized and received single-dose azithromycin (500 mg; 106 persons), levofloxacin (500 mg; 111 persons), or rifaximin (1650 mg; 107 persons), in combination with loperamide (labeled dosing). The efficacy outcomes included clinical cure at 24 hours and time to last unformed stool.

Results

Clinical cure at 24 hours occurred in 81.4%, 78.3%, and 74.8% of the levofloxacin, azithromycin, and rifaximin arms, respectively. Compared with levofloxacin, azithromycin was not inferior (P = .01). Noninferiority could not be shown with rifaximin (P = .07). At 48 and 72 hours, efficacy among regimens was equivalent (approximately 91% at 48 and 96% at 72 hours). The median time to last unformed stool did not differ between treatment arms (azithromycin, 3.8 hours; levofloxacin, 6.4 hours; rifaximin, 5.6 hours). Treatment failures were uncommon (3.8%, 4.4%, and 1.9% in azithromycin, levofloxacin, and rifaximin arms, respectively) (P = .55). There were no differences between treatment arms with postdose nausea, vomiting, or other adverse events.

Conclusions

Single-dose azithromycin, levofloxacin, and rifaximin with loperamide were comparable for treatment of acute watery diarrhea.

Clinical Trial Registration

NCT01618591.

Enterotoxigenic Escherichia coli-blood group A interactions intensify diarrheal severity

Enterotoxigenic Escherichia coli (ETEC) infections are highly prevalent in developing countries, where clinical presentations range from asymptomatic colonization to severe cholera-like illness. The molecular basis for these varied presentations, which may involve strain-specific virulence features as well as host factors, has not been elucidated. We demonstrate that, when challenged with ETEC strain H10407, originally isolated from a case of cholera-like illness, blood group A human volunteers developed severe diarrhea more frequently than individuals from other blood groups. Interestingly, a diverse population of ETEC strains, including H10407, secrete the EtpA adhesin molecule. As many bacterial adhesins also agglutinate red blood cells, we combined the use of glycan arrays, biolayer inferometry, and noncanonical amino acid labeling with hemagglutination studies to demonstrate that EtpA is a dominant ETEC blood group A-specific lectin/hemagglutinin. Importantly, we have also shown that EtpA interacts specifically with glycans expressed on intestinal epithelial cells from blood group A individuals and that EtpA-mediated bacterial-host interactions accelerate bacterial adhesion and effective delivery of both the heat-labile and heat-stable toxins of ETEC. Collectively, these data provide additional insight into the complex molecular basis of severe ETEC diarrheal illness that may inform rational design of vaccines to protect those at highest risk.

Review: chronic and persistent diarrhea with a focus in the returning traveler

Background

Travelers’ diarrhea is a common malady afflicting up to 50% of travelers after a 2-week travel period. An appreciable percentage of these cases will become persistent or chronic. We summarized the published literature reporting persistent/chronic diarrhea in travelers elucidating current understanding of disease incidence, etiology and regional variability.

Methods

We searched electronic databases (Medline, Embase, and Cochrane database of clinical trials) from 1990 to 2015 using the following terms: “chronic or persistent diarrh* and (returning) travel* or enteropathogen, GeoSentinel, and travel-associated infection. Included studies published in the English language on adult returning travelers (duration < 3-months) reporting denominator data. Point estimates and standard 95% confidence intervals were calculated for incidence using a random-effects model. Study incidence heterogeneity rates were assessed using x² heterogeneity statistics, graphically represented with Forest plots.

Results

We identified 19 studies meeting the inclusion criteria (all published after 1999). 18 studies reported upon the incidence of persistent/chronic diarrhea as a syndromic diagnosis in returning travelers; one study reported adequate denominator data from which to assess pathogen specific etiology. Giardiasis comprise an appreicaible percentage of infectious mediated persistent/chronic diarrhea in returning travelers. The overall estimate of persistent/chronic diarrhea incidence was 6% (0.05–0.07) in 321,454, travelers; with significant heterogeniety observed across regions. The total number of regional travelers, and point estimates for incidence (95% CI) for Latin American, African, and Asian travelers were [15816 (0.09 [0.07–0.11]), 42290 (0.06 [0.05–0.07]), and 27433 (0.07 [0.06–0.09])] respectively. We identified lower published rates of chronic diarrhea from Sub-Saharan Africa relative to [North Africa, South Central Asia, and Central America]. Persistent/chronic diarrhea ranked fourth as a syndromic diagnosis in all regions.

Conclusions

Persistent/Chronic diarrhea is a leading syndromic diagnosis in returning travelers across all regions. The 6% incidence [proportionate morbidity (PM) of 60] observed in over >300,000 global travelers is comparable to prior estimates. We identified lower published rates of chronic diarrhea from Sub-Saharan Africa relative to [North Africa, South Central Asia, and Central America]. Giardiasis comprises an appreciabile percentatge of travel-associated infectious mediated persistent/chronic diarrhea. There’s a dearth of published data characterizing the incidence of specific enteropathogenic etiologies for persistent/chronic diarrhea in returning travelers.

Breadth of function and homing capacity of peripheral CD4+ Th responses to intradermal (ID) immunization with enterotoxigenic E. coli fimbrial tip adhesin CfaE plus adjuvant LTR192G

ETEC are a leading cause of traveler’s diarrhea and a vaccine development priority for the US military. A subunit vaccine comprised of ETEC fimbrial tip adhesin, CfaE, adjuvanted with single-mutant heat-labile toxin, LTR192G, was given ID 3 times, 21 days apart, and evaluated for immunogenicity and efficacy against moderate to severe diarrhea (MSD) following CFA/I+ ETEC oral challenge. The homing phenotype, activation status, and cytokine production of circulating CD4+ T cells following vaccination were assessed by flow cytometry to understand the response generated by mucosal adjuvant, LT, introduced via the skin, and the potential mechanisms involved in protection from an enteric pathogen.

Following in vitro stimulation with CfaE or LT 15mers, PBMCs of most vaccinated subjects expressed IFNγ or IL-17, within multiple homing subsets. Specifically, activated CfaE-specific α4β7+IFNγ+ cells were detected in 69% of vaccinated subjects, suggesting potential for gut homing, while 58% subjects generated CD62L+IFNγ+ responses. LT-specific IFNγ was observed in CD62L+ and CLA+ cells (52% and 50% subjects, respectively). Both CfaE- and LT-specific IL-17 were identified in CCR6+ (65%, 66% subjects, respectively) and CD62L+ cells (65%, 58%).

Subjects without MSD following experimental challenge had significantly higher CfaE-specific activated (CD154+) α4β7+ cells (p=0.043, t-test), as well as IFNγ (p = 0.036) and IL-17 (p = 0.008) responses to vaccination. LT-specific activation of CLA+ cells (p = 0.035) and IL-17 (p = 0.032) levels were also higher in subjects without MSD. Overall, ID vaccination with CfaE and LTR192G elicited broadly homing and functional Th cell responses that may play a role in protection at the mucosal level.

Safety and Immunogenicity of a Candidate Bioconjugate Vaccine against Shigella flexneri 2a Administered to Healthy Adults: a Single-Blind, Randomized Phase I Study

Several candidate vaccines against Shigella spp. are in development, but the lack of a clear correlate of protection from challenge with the induction of adequate immune responses among the youngest age groups in the developing world has hampered Shigella vaccine development over the past several decades. Bioconjugation technology, exploited here for an Shigella flexneri 2a candidate vaccine, offers a novel and potentially cost-effective way to develop and produce vaccines against a major pathogen of global health importance. Flexyn2a, a novel S. flexneri 2a bioconjugate vaccine made of the polysaccharide component of the S. flexneri 2a O-antigen, conjugated to the exotoxin protein A of Pseudomonas aeruginosa (EPA), was evaluated for safety and immunogenicity among healthy adults in a single-blind, phase I study with a staggered randomization approach. Thirty subjects (12 receiving 10 μg Flexyn2a, 12 receiving Flexyn2a with aluminum adjuvant, and 6 receiving placebo) were administered two injections 4 weeks apart and were followed for 168 days. Flexyn2a was well-tolerated, independently of the adjuvant and number of injections. The Flexyn2a vaccine elicited statistically significant S. flexneri 2a lipopolysaccharide (LPS)-specific humoral responses at all time points postimmunization in all groups that received the vaccine. Elicited serum antibodies were functional, as evidenced by bactericidal activity against S. flexneri 2a. The bioconjugate candidate vaccine Flexyn2a has a satisfactory safety profile and elicited a robust humoral response to S. flexneri 2a LPS with or without inclusion of an adjuvant. Moreover, the bioconjugate also induced functional antibodies, showing the technology's features in producing a promising candidate vaccine. (This study has been registered at ClinicalTrials.gov under registration no. NCT02388009.).

Giardia lamblia infection increases risk of chronic gastrointestinal disorders

BACKGROUND

Giardia lamblia is a common parasitic cause of infectious gastroenteritis in the United States and the world and may be linked to an increased risk of chronic gastrointestinal (GI) disorders. We sought to assess the risk of several chronic GI disorders following Giardia infection among active duty US military personnel.

METHODS

This study was designed as a retrospective cohort study in which active duty military personnel with documented G. lamblia infection were assessed for the subsequent risk of developing a chronic GI disorder including irritable bowel syndrome (IBS), dyspepsia and gastroesophageal reflux disease (GERD). Post-giardia chronic GI disorder risk was compared to risk in uninfected personnel matched on several demographic characteristics and medical encounter information. Data were obtained from the Defense Medical Surveillance System and exposures (1998-2009) with outcomes identified based on documented medical encounters with specific medical billing codes. Modified Poisson regression was used to evaluate the relationship between G. lamblia infection and chronic GI disorders.

RESULTS

A total of 80 Giardia cases were identified for an estimated incidence of 0.55 cases per 100,000 person-years. Cases were matched to 294 unexposed subjects. After adjusting for important covariates, there was an increased risk of IBS (relative risk: 2.1, p = 0.03) associated with antecedent Giardia infection.

CONCLUSION

These data add to a growing body of literature and demonstrate an increased risk of IBS after infection with G. lamblia.

An Evidenced-Based Scale of Disease Severity following Human Challenge with Enteroxigenic Escherichia coli

Background

Experimental human challenge models have played a major role in enhancing our understanding of infectious diseases. Primary outcomes have typically utilized overly simplistic outcomes that fail to entirely account for complex illness syndromes. We sought to characterize clinical outcomes associated with experimental infection with enterotoxigenic Escherichia coli (ETEC) and to develop a disease score.

Methods

Data were obtained from prior controlled human ETEC infection studies. Correlation and univariate regression across sign and symptom severity was performed. A multiple correspondence analysis was conducted. A 3-parameter disease score with construct validity was developed in an iterative fashion, compared to standard outcome definitions and applied to prior vaccine challenge trials.

Results

Data on 264 subjects receiving seven ETEC strains at doses from 1x10⁵ to 1x10¹⁰ cfu were used to construct a standardized dataset. The strongest observed correlation was between vomiting and nausea (r = 0.65); however, stool output was poorly correlated with subjective activity-impacting outcomes. Multiple correspondence analyses showed covariability in multiple signs and symptoms, with severity being the strongest factor corresponding across outcomes. The developed disease score performed well compared to standard outcome definitions and differentiated disease in vaccinated and unvaccinated subjects.

Conclusion

Frequency and volumetric definitions of diarrhea severity poorly characterize ETEC disease. These data support a disease severity score accounting for stool output and other clinical signs and symptoms. Such a score could serve as the basis for better field trial outcomes and gives an additional outcome measure to help select future vaccines that warrant expanded testing in pivotal pre-licensure trials.

Infectious Gastroenteritis as a Risk Factor for Tropical Sprue and Malabsorption: A Case-Control Study

BACKGROUND

Previous studies have linked an increase in functional and pathological gastrointestinal (GI) disorders following antecedent infectious gastroenteritis (IGE), yet studies of other chronic GI disorders such as tropical sprue (TS) and intestinal malabsorption (IM) are lacking. This study was performed to evaluate the association between documented IGE and the risk of TS and IM using a matched case-control study.

METHODS

The odds of IGE (exposure) among subjects with TS and IM were compared to the odds of exposure in matched controls. Data were obtained from the Defense Medical Surveillance System. Incidence was estimated based on the number of active duty military personnel, and conditional logistic regression models were used to evaluate the relationship between IGE and TS/IM while adjusting for potential confounders.

RESULTS

The overall incidence of TS and IM was 0.24 and 1.98 per 100,000 person-years, respectively. After adjusting for important covariates, prior IGE was associated with an increase in the odds of TS (odds ratio (OR) 36.64) and IM (OR 3.93) (p < 0.001). Other covariates demonstrating an increased risk were being of Caucasian race, having greater than high school education, and service in military branches other than the Army.

CONCLUSION

Overall, this study demonstrates the first significant estimates that a case of antecedent IGE is associated with an increased risk of TS and IM in an active duty military population. Ultimately, acquisition of TS or IM has the potential to decrease operational efficiency, which may have a significant impact on deployed military missions.

Postinfectious functional gastrointestinal disorders: a focus on epidemiology and research agendas

Epidemiologic research is fundamental and complementary to our understanding of disease and development of primary, secondary, and tertiary interventions. To put the current evidence into context and identify gaps and research priorities in the areas of disease attribution, burden of disease, clinical characterization, and management of postinfectious functional gastrointestinal disorders (PI-FGDs), we took a multidisciplinary approach from the domains of infectious disease, gastroenterology, epidemiology, and public health. Our review of data from these disciplines found that, despite a complete understanding of pathoetiology, studies continue to accumulate and point toward evidence of a causal association for FGD. For some FGDs, Bradford Hill's criteria for causality yield more certainty than other criteria. In addition, the growing recognition of the impact of acute foodborne illness on economics and society is leading to exploration of the potential long-term health effects and disease burden of PI-FGDs, although a paucity of data exist in terms of pathogen-specific risk, disability duration, and relevant disability weights. Lastly, the understanding of PI-FGDs is changing the way research is approached and suggests a need for a more expansive exploration of biologic mechanisms and how FGDs are categorized. Areas of research priorities are catalogued in this paper and will hopefully provide inspiration for future studies and contributions to the field of gastroenterology.

The chronic gastrointestinal consequences associated with campylobacter

Campylobacteriosis is a leading cause of acute infectious diarrhea in the developing world, where it causes considerable mortality, and in developed countries, where it accounts for significant healthcare and other costs. Evidence has emerged from basic science, clinical, and epidemiological domains that suggests that Campylobacter infection is not limited to acute illness but is also involved in the development of well-described extraintestinal sequelae, such as the Guillain-Barré syndrome and reactive arthritis, and may also contribute to the pathogenesis of chronic gastrointestinal conditions. This review will focus on the role of Campylobacter infection as a risk factor for the development of chronic gastrointestinal sequelae, such as functional gastrointestinal disorders, with which irritable bowel syndrome has been most frequently associated, inflammatory bowel disease, and celiac disease.