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

Extracellular components in enteroaggregative Escherichia coli biofilm and impact of treatment with proteinase K, DNase or sodium metaperiodate

Enteroaggregative E. coli (EAEC) is a major cause of diarrhea worldwide. EAEC are highly adherent to cultured epithelial cells and make biofilms. Both adherence and biofilm formation rely on the presence of aggregative adherence fimbriae (AAF). We compared biofilm formation from two EAEC strains of each of the five AAF types. We found that AAF type did not correlate with the level of biofilm produced. Because the composition of the EAEC biofilm has not been fully described, we stained EAEC biofilms to determine if they contained protein, carbohydrate glycoproteins, and/or eDNA and found that EAEC biofilms contained all three extracellular components. Next, we assessed the changes to the growing or mature EAEC biofilm mediated by treatment with proteinase K, DNase, or a carbohydrate cleavage agent to target the different components of the matrix. Growing biofilms treated with proteinase K had decreased biofilm staining for more than half of the strains tested. In contrast, although sodium metaperiodate only altered the biofilm in a quantitative way for two strains, images of biofilms treated with sodium metaperiodate showed that the EAEC were more spread out. Overall, we found variability in the response of the EAEC strains to the treatments, with no one treatment producing a biofilm change for all strains. Finally, once formed, mature EAEC biofilms were more resistant to treatment than biofilms grown in the presence of those same treatments.

Gut microbiome and antibiotic resistance effects during travelers' diarrhea treatment and prevention

IMPORTANCE

The travelers' gut microbiome is potentially assaulted by acute and chronic perturbations (e.g., diarrhea, antibiotic use, and different environments). Prior studies of the impact of travel and travelers' diarrhea (TD) on the microbiome have not directly compared antibiotic regimens, and studies of different antibiotic regimens have not considered travelers' microbiomes. This gap is important to be addressed as the use of antibiotics to treat or prevent TD-even in moderate to severe cases or in regions with high infectious disease burden-is controversial based on the concerns for unintended consequences to the gut microbiome and antimicrobial resistance (AMR) emergence. Our study addresses this by evaluating the impact of defined antibiotic regimens (single-dose treatment or daily prophylaxis) on the gut microbiome and resistomes of deployed servicemembers, using samples collected during clinical trials. Our findings indicate that the antibiotic treatment regimens that were studied generally do not lead to adverse effects on the gut microbiome and resistome and identify the relative risks associated with prophylaxis. These results can be used to inform therapeutic guidelines for the prevention and treatment of TD and make progress toward using microbiome information in personalized medical care.

Outbreak of Diarrhea Caused by a Novel Cryptosporidium hominis Subtype During British Military Training in Kenya

Background

We report clinical, epidemiological, and laboratory features of a large diarrhea outbreak caused by a novel Cryptosporidium hominis subtype during British military training in Kenya between February and April 2022.

Methods

Data were collated from diarrhea cases, and fecal samples were analyzed on site using the multiplex polymerase chain reaction (PCR) BioFire FilmArray. Water was tested using Colilert kits (IDEXX, UK). DNA was extracted from feces for molecular characterization of Cryptosporidium A135, Lib13, ssu rRNA, and gp60 genes.

Results

One hundred seventy-two of 1200 (14.3%) personnel at risk developed diarrhea over 69 days. One hundred six primary fecal samples were tested, and 63/106 (59.4%; 95% CI, 0.49%-0.69%) were positive for Cryptosporidium spp. Thirty-eight had Cryptosporidium spp. alone, and 25 had Cryptosporidium spp. with ≥1 other pathogen. A further 27/106 (25.5%; 95% CI, 0.18%-0.35%) had non-Cryptosporidium pathogens only, and 16/106 (15.1%; 95% CI, 0.09%-0.23%) were negative. C. hominis was detected in 58/63 (92.1%) Cryptosporidium spp.-positive primary samples, but the others were not genotypable. Twenty-seven C. hominis specimens were subtypable; 1 was gp60 subtype IeA11G3T3, and 26 were an unusual subtype, ImA13G1 (GenBank accession OP699729), supporting epidemiological evidence suggesting a point source outbreak from contaminated swimming water. Diarrhea persisted for a mean (SD) of 7.6 (4.6) days in Cryptosporidium spp. cases compared with 2.3 (0.9) days in non-Cryptosporidium cases (P = .001).

Conclusions

Real-time multiplex PCR fecal testing was vital in managing this large cryptosporidiosis outbreak. The etiology of a rare C. hominis gp60 subtype emphasizes the need for more genotypic surveillance to identify widening host and geographic ranges of novel C. hominis subtypes.

Development of a new travellers' diarrhoea clinical severity classification and its utility in confirming rifamycin-SV efficacy

BACKGROUND

travellers' diarrhoea (TD) is frequently reported with incidence up to 40% in high-risk destinations. Previous studies showed that the number of loose stools alone is inadequate to holistically predict the severity of TD. To improve the prediction of prognosis and to optimize treatments, a simple risk-based clinical severity classification has been developed.

METHODS

pooled baseline data of signs and symptoms and number of loose stools from 1098 subjects enrolled in two double-blind Phase 3 trials of rifamycin-SV were analyzed with correlation, multiple correspondence analyses, prognostic factor criteria, and Contal and O'Quigley method to generate a TD severity classification (mild, moderate and severe). The relative importance of this classification on resolution of TD was assessed by Cox proportional model hazard model on the time to last unformed stool (TLUS).

RESULTS

the analysis showed that TLUS were longer for the severe [hazard ratio (HR) 0.24; P < 0.001; n = 173] and moderate (HR 0.54; P = 0.0272; n = 912) vs mild. Additionally, when the treatment assigned in the studies was investigated in the severity classification, the results yielded that rifamycin-SV significantly shortened TLUS vs placebo for all subjects (HR 1.9; P = 0.0006), severe (HR 5.9; P = 0.0232) and moderate (HR 1.7; P = 0.0078) groups and was as equally efficacious as ciprofloxacin for all subjects, moderate and severe groups (HRs: 0.962, 0.9, 1.2; all P = NS, respectively). When reassessed by this classification, rifamycin-SV showed consistent efficacy with the Phase 3 studies.

CONCLUSIONS

this newly developed TD clinical severity classification demonstrated strong prognostic value and clinical utility by combining patients' multiple signs and symptoms of enteric infection and number of loose stools to provide a holistic assessment of TD. By expanding on the current classification by incorporating patient reported outcomes in addition to TLUS, a classification like the one developed, may help optimize patient selection for future clinical studies.

Prevalence and Persistence of Antibiotic Resistance Determinants in the Gut of Travelers Returning to the United Kingdom is Associated with Colonization by Pathogenic Escherichia coli

The gut microbiota constitutes an ideal environment for the selection, exchange, and carriage of antibiotic resistance determinants (ARDs), and international travel has been identified as a risk factor for acquisition of resistant organisms. Here, we present a longitudinal metagenomic analysis of the gut resistome in travellers to "high-risk" countries (Gutback). Fifty volunteers, recruited at a travel clinic in London, United Kingdom, provided stool samples before (pre-travel), immediately after (post-travel), and 6 months after their return (follow-up) from a high-risk destination. Fecal DNA was extracted, metagenomic sequencing performed and the resistome profiled. An increase in abundance and diversity of resistome was observed after travel. Significant increases in abundance were seen in antimicrobial genes conferring resistance to macrolides, third-generation cephalosporins, aminoglycosides, and sulfonamides. There was a significant association with increased resistome abundance if the participant experienced diarrhea during travel or took antibiotics, but these two variables were co-correlated. The resistome abundance returned to pre-travel levels by the 6-month sample point but there was evidence of persistence of several ARDs. The post-travel samples had an increase in abundance Escherichia coli which was positively associated with many acquired resistant determinants. Virulence and phylogenetic profiling revealed pathogenic E. coli significantly contributed to this increase abundance. In summary, in this study, foreign travel remains a significant risk factor for acquisition of microbes conferring resistance to multiple classes of antibiotics, often associated with symptomatic exposure to diarrhoeagenic E. coli. IMPORTANCE A future where antimicrobial therapy is severely compromised by the increase in resistant organisms is of grave concern. Given the variability in prevalence and diversity of antimicrobial resistance determinants in different geographical settings, international travel is a known risk factor for acquisition of resistant organisms into the gut microbiota. In this study, we show the utility of metagenomic approaches to quantify the levels of acquisition and carriage of resistance determinants after travel to a "high-risk" setting. Significant modulation to the resistome was seen after travel that is largely resolved within 6 months, although evidence of persistence of several ARDs was observed. Risk factors for acquisition included experiencing a diarrheal episode and the use of antibiotics. Colonization by pathogenic Escherichia coli was correlated with an increase in acquisition of antimicrobial resistance determinants, and as such established public health guidance to travelers on food and water safety remain an important message to reduce the spread of antibiotic resistance.

British Association of Sexual Health and HIV (BASHH) United Kingdom national guideline for the management of sexually transmitted enteric infections 2023

This is the first British Association of Sexual Health and HIV (BASHH) national guideline for the management of sexually transmitted enteric infections (STEI). This guideline is primarily aimed for level 3 sexual health clinics; however, it may also be applicable to other settings such as primary care or other hospital departments where individuals with STEI may present. This guideline makes recommendations on testing, management, partner notification and public health control of STEI.

A single dose of ciprofloxacin reduces the duration of diarrhea among service members deployed in Africa

OBJECTIVES

To assess the effectiveness of the adjunction of a one-gram single dose of ciprofloxacin to a symptomatic treatment for the early treatment of uncomplicated diarrhea during military operations of the French service members in Africa.

PATIENTS AND METHODS

This phase IV, multicentric, randomized, open-label, controlled trial was conducted in Chad, Mali, and in Central African Republic. A total of 267 French service members having at least one loose stool in the previous 24 hours were enrolled from May 2015 to June 2016. Participants were randomized to receive ciprofloxacin 1 g and a symptomatic treatment (racecadotril 100 mg three times a day and ad libidum oral rehydration solution) or a symptomatic treatment alone. The primary outcome was the duration of the diarrhea. Secondary outcomes were evaluated at the 72-hour endpoint and included recovery status, number of loose stools, frequency and duration of associated symptoms and safety of treatments.

RESULTS

Among 267 participants, 242 completed the trial. Participants receiving ciprofloxacin and a symptomatic treatment (n = 124) were significantly more likely to be cured at the endpoint than those who only received a symptomatic treatment (118): 94.4 % versus 74.6 % (OR = 5.7; 95 %CI: [2.4-13.6]; p < 10^-3). The antibiotic therapy reduced the average diarrhea duration by 30 % (p = 10^-4). Fever at inclusion was associated with a longer episode (HR = 0.61; 95 %CI: [0.41-0.89]; p = 0.012). No adverse event of medications was reported.

CONCLUSION

A single dose of ciprofloxacin was effective and safe in treating uncomplicated diarrhea among service members in Africa.

Molecular Epidemiology of Escherichia coli with Resistance against Third-Generation Cephalosporines Isolated from Deployed German Soldiers-A Retrospective Assessment after Deployments to the African Sahel Region and Other Sites between 2007 and 2016

Colonization and infection with bacteria with acquired antibiotic resistance are among the risks for soldiers on international deployments. Enterobacterales with resistance against third-generation cephalosporines are amongst the most frequently imported microorganisms. To contribute to the scarcely available epidemiological knowledge on deployment-associated resistance migration, we assessed the molecular epidemiology of third-generation cephalosporine-resistant Escherichia coli isolated between 2007 and 2016 from German soldiers after deployments, with a particular focus on the African Sahel region. A total of 51 third-generation cephalosporine-resistant E. coli isolated from 51 military returnees from deployment collected during the assessment period between 2007 and 2016 were subjected to short-read next-generation sequencing analysis. Returnees from the Sahel region (Djibouti, Mali, South Sudan, Sudan, Sudan, and Uganda) comprised a proportion of 52.9% (27/51). Repeatedly isolated sequence types according to the Warwick University scheme from returnees from the Sahel region were ST38, ST131, and ST648, confirming previous epidemiological assessments from various sub-Saharan African regions. Locally prevalent resistance genes in isolates from returnees from the Sahel region associated with third-generation resistance were bla_CTX-M-15, bla_CTX-M-27, bla_CTX-M-1, bla_TEM-169, bla_CTX-M-14, bla_CTX-M-99-like, bla_CTX-M-125, bla_SHV-12, and bla_DHA-1, while virulence genes were east1, sat, and tsh in declining order of frequency of occurrence each. In line with phenotypically observed high resistance rates for aminoglycosides and trimethoprim/sulfamethoxazole, multiple associated resistance genes were observed. A similar, slightly more diverse situation was recorded for the other deployment sites. In summary, this assessment provides first next-generation sequencing-based epidemiological data on third-generation cephalosporine-resistant E. coli imported by deployed German soldiers with a particular focus on deployments to the Sahel region, thus serving as a small sentinel. The detected sequence types are well in line with the results from previous epidemiological assessments in sub-Saharan Africa.

Communicable diseases in humanitarian operations and disasters

Military organisations have battled communicable disease for millennia. They have pioneered disease prevention from the Crusades to the World Wars and continue to do so today. Predeployment vaccinations and chemoprophylaxis are effective in preventing communicable disease, as is reliable vector destruction and bite prevention, especially in the era of multidrug resistant organisms. These measures are unlikely to be fully possible in disasters, but reactive vaccination and efforts to reduce exposure to communicable disease should be a priority. Communicable diseases can be challenging to diagnose-the UK Defence Medical Services have become familiar with tools such as multiplex PCR and mass spectrometry. These have the potential to accurately identify organisms and sensitivity patterns in austere environments. Management of communicable diseases depends on accurate diagnosis and has a largely well-established evidence base but can be limited by a lack of resources and skills in an austere setting, therefore telemedicine can assist diagnosis and treatment of infections by projecting specialist skill. Systems such as EpiNATO2 are useful in monitoring diseases and identifying trends in order to establish control measures. Many of these tools and techniques are effective in austere environments and offer learning opportunities for those providing care in similar settings. Further research is ongoing into diagnostic tools as well as remote management.

Bacterial travellers' diarrhoea: A narrative review of literature published over the past 10 years

Travellers' diarrhoea (TD) is the most frequent illness experienced by international travellers to lower-income countries with bacterial agents considered to account for 80-90% of cases. In this review, we summarise evidence published on bacterial TD over the past 10 years, focusing on the epidemiology and aetiology of TD. Diarrhoeagenic Escherichia coli (DEC) continue to be the most commonly implicated bacteria in TD, although Enteropathogenic E. coli (EPEC) and Enteroaggregative E. coli (EAEC) now appear to be predominant where Enterotoxigenic E. coli (ETEC) was previously considered most prevalent globally. Where fluroquinolone resistance had primarily been documented for Campylobacter in Southeast Asia, widespread resistance has been observed in most regions of the world for multiple enteropathogens, including Shigella, Salmonella, ETEC and EAEC. Implementation of novel molecular methods for pathogen detection has led to identification of bacterial pathogens, including Clostridium difficile (with and without the use of prior antibiotics), Arcobacter species and Bacteroides fragilis, as aetiological agents in TD. The widespread resistance to first-line antibiotics in multiple bacterial enteropathogens warrants continued surveillance and re-evaluation of current treatment practices. Further investigations are required to determine the prevalence and geographical distribution of bacterial enteropathogens that have been more recently implicated in TD.

A disease severity scale for the evaluation of vaccine and other preventive or therapeutic interventions for travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea (TD) is the most common travel-related illness with an estimated 10 million people afflicted annually. Outcome measures to assess the efficacy of primary and secondary TD interventions were historically based on diarrhoea frequency with ≥1 associated gastrointestinal symptom. Furthermore, efficacy determination is often made on the presence or absence of TD, rather than on TD illness severity. Current severity classifications are based on subjective consideration of impact of illness on activity. We sought to develop a standardized scoring system to characterize TD severity to potentially apply as a secondary outcome in future field studies.

METHODS

Data on multiple signs and symptoms were obtained from a previously published multisite TD treatment trial conducted by the US Department of Defense (TrEAT TD). Correlation, regression and multiple correspondence analyses were performed to assess impact on activity and a TD severity score was established.

RESULTS

Numerous signs and symptoms were associated with impaired function, with malaise and nausea most strongly associated [odds ratio (OR) 5.9-44.3, P < 0.0001 and OR 2.8-37.1, P < 0.0001, respectively). Based on co-varying symptomatology, a TD severity score accounting for diarrhoea frequency in addition to several signs and symptoms was a better predictor of negative impact on function than any single sign/symptom (X2 = 127.16, P < 0.001). Additionally, there was a significant difference (P < 0.0001) in the mean TD severity score between those with acute watery diarrhoea (3.9 ± 1.9) and those with dysentery or acute febrile illness (6.2 ± 2.0).

CONCLUSIONS

The newly developed disease severity score better predicted a negative impact on activity due to TD than did any single sign or symptom. Incorporating multiple parameters into the TD severity score better captures illness severity and moves the field towards current recommendations for TD management by considering symptoms with high functional impact. Further validation of this score is needed in non-military travellers and other settings.

What's new in travellers' diarrhoea: updates on epidemiology, diagnostics, treatment and long-term consequences

BACKGROUND

Travellers' diarrhoea (TD) is the most common clinical syndrome affecting travellers. This narrative review summarizes key discoveries reported in the last two years related to TD and suggests areas for future research.

METHODS

A PubMed literature search was conducted for novel data in TD research published between 12 January 2018 and 12 January 2020. Inclusion was based on contribution to epidemiology, aetiology, diagnostics, management and long-term consequences and relevance to public health, discovery and clinical practice.

RESULTS

The initial literature search yielded 118 articles. We retrieved 72 and reviewed 31 articles for inclusion. The findings support our understanding that TD incidence varies by traveller group and environment with students and military-travel remaining moderately high risk, and control of food and water in mass gathering events remain an important goal. The growth of culture-independent testing has led to a continued detection of previously known pathogens, but also an increased detection frequency of norovirus. Another consequence is the increase in multi-pathogen infections, which require consideration of clinical, epidemiological and diagnostic data. Fluoroquinolone resistant rates continue to rise. New data on non-absorbable antibiotics continue to emerge, offering a potential alternative to current recommendations (azithromycin and fluoroquinolones), but are not recommended for febrile diarrhoea or dysentery or regions/itineraries where invasive pathogens are likely to cause illness. Recent studies investigated the interaction of the microbiome in TD prevention and consequences, and while discriminating features were identified, much uncertainty remains. The prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) acquisition and carriage is increasing. Finally, continued research documents the post-infectious consequences, whereas mechanisms of reactive arthritis and post-infectious IBS necessitate further investigation.

CONCLUSIONS

Globally, TD remains an important travel health issue and advances in our understanding continue. More research is needed to mitigate risk factors where possible and develop risk-based management strategies to reduce antibiotic usage and its attendant consequences.

The Controlled Human Infection Model for Enterotoxigenic Escherichia coli

The controlled human infection model (CHIM) for enterotoxigenic Escherichia coli (ETEC) has been instrumental in defining ETEC as a causative agent of acute watery diarrhea, providing insights into disease pathogenesis and resistance to illness, and enabling preliminary efficacy evaluations for numerous products including vaccines, immunoprophylactics, and drugs. Over a dozen strains have been evaluated to date, with a spectrum of clinical signs and symptoms that appear to replicate the clinical illness seen with naturally occurring ETEC. Recent advancements in the ETEC CHIM have enhanced the characterization of clinical, immunological, and microbiological outcomes. It is anticipated that omics-based technologies applied to ETEC CHIMs will continue to broaden our understanding of host-pathogen interactions and facilitate the development of primary and secondary prevention strategies.

Fecal Microbiota Functional Gene Effects Related to Single-Dose Antibiotic Treatment of Travelers' Diarrhea

Background

Travelers' diarrhea (TD) is common among military personnel deployed to tropical and subtropical regions. It remains unclear how TD and subsequent antibiotic treatment impact the resident microflora within the gut, especially given increased prevalence of antibiotic resistance among enteric pathogens and acquisition of multidrug-resistant organisms. We examined functional properties of the fecal microflora in response to TD, along with subsequent antibiotic treatment.

Methods

Fecal samples from US and UK military service members deployed to Djibouti, Kenya, and Honduras who presented with acute watery diarrhea were collected. A sample was collected at acute presentation to the clinic (day 0, before antibiotics), as well as 7 and/or 21 days following a single dose of antibiotics (azithromycin [500 mg], levofloxacin [500 mg], or rifaximin [1650 mg], all with loperamide). Each stool sample underwent culture and TaqMan reverse transcription polymerase chain reaction analyses for pathogen and antibiotic resistance gene detection. Purified DNA from each sample was analyzed using the HumiChip3.1 functional gene array.

Results

In total, 108 day 1 samples, 50 day 7 samples, and 94 day 21 samples were available for analysis from 119 subjects. Geographic location and disease severity were associated with distinct functional compositions of fecal samples. There were no overt functional differences between pre- and postantibiotic treatment samples, nor was there increased acquisition of antibiotic resistance determinants for any of the antibiotic regimens.

Conclusions

These results indicate that single-dose antibiotic regimens may not drastically alter the functional or antibiotic resistance composition of fecal microflora, which should inform clinical practice guidelines and antimicrobial stewardship.

Clinical Trials Registration Number

NCT01618591.

The Pretravel Consultation: Recent Updates

Estimates suggest that 43%-79% of international travelers may develop travel-related illnesses. Most such illnesses are considered mild and self-limited; however, some are life-threatening. The pretravel consultation is aimed at assessing risks for a range of illnesses, communicating these risks, and then providing individualized recommendations and interventions to minimize or manage such risks. The effective consultation is predicated on a well-prepared clinician and motivated traveler, understanding the traveler's perception of, and tolerance for, risk, and providing education applicable to the actual itinerary. Integral to the clinician's preparation is regular review of up-to-date trip-specific recommendations; country-specific information and recommendations are readily available and can now be efficiently accessed. From the infectious diseases perspective, immunizations, malaria chemoprophylaxis, insect repellent use, and travelers' diarrhea and its self-management are cornerstones of the consultation. This review focuses primarily on updating these 4 topics with recently published information relevant to adult travelers.

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.

Genetic and Virulence Profiles of Enteroaggregative Escherichia coli (EAEC) Isolated From Deployed Military Personnel (DMP) With Travelers' Diarrhea

To discern if there was a particular genotype associated with clinical enteroaggregative Escherichia coli (EAEC) strains isolated from deployed military personnel (DMP) with travelers' diarrhea (TD), we characterized a collection of EAEC from DMP deployed to Afghanistan, Djibouti, Kenya, or Honduras. Although we did not identify a specific EAEC genotype associated with TD in DMP, we found that EAEC isolated at the first clinic visit were more likely to encode the dispersin gene aap than EAEC collected at follow-up visits. A majority of the EAEC isolates were typical EAEC that adhered to HEp-2 cells, formed biofilms, and harbored genes for aggregative adherence fimbriae (AAF), AggR, and serine protease autotransporters of Enterobacteriaceae (SPATEs). A separate subset of the EAEC had aggR and genes for SPATEs but encoded a gene highly homologous to that for CS22, a fimbriae more commonly found in enterotoxigenic E. coli. None of these CS22-encoding EAEC formed biofilms in vitro or adhered to HEp-2 cells. Whole genome sequence and single nucleotide polymorphism analyses demonstrated that most of the strains were genetically diverse, but that a few were closely related. Isolation of these related strains occurred within days to more than a year apart, a finding that suggests a persistent source and genomic stability. In an ampicillin-treated mouse model we found that an agg4A+ aar- isolate formed a biofilm in the intestine and caused reduced weight gain in mice, whereas a strain that did not form an in vivo biofilm caused no morbidity. Our diverse strain collection from DMP displays the heterogeneity of EAEC strains isolated from human patients, and our mouse model of infection indicated the genotype agg4A+ aar– and/or capacity to form biofilm in vivo may correlate to disease severity.

Meeting report of the third annual Tri-Service Microbiome Consortium symposium

The Tri-Service Microbiome Consortium (TSMC) was founded to enhance collaboration, coordination, and communication of microbiome research among U.S. Department of Defense (DoD) organizations and to facilitate resource, material and information sharing among consortium members. The 2019 annual symposium was held 22-24 October 2019 at Wright-Patterson Air Force Base in Dayton, OH. Presentations and discussions centered on microbiome-related topics within five broad thematic areas: 1) human microbiomes; 2) transitioning products into Warfighter solutions; 3) environmental microbiomes; 4) engineering microbiomes; and 5) microbiome simulation and characterization. Collectively, the symposium provided an update on the scope of current DoD microbiome research efforts, highlighted innovative research being done in academia and industry that can be leveraged by the DoD, and fostered collaborative opportunities. This report summarizes the presentations and outcomes of the 3rd annual TSMC symposium.

Transcriptional and Translational Inhibitors Block SOS Response and Shiga Toxin Expression in Enterohemorrhagic Escherichia coli

Shiga toxins (Stx) induce the symptoms of the life-threatening hemolytic uremic syndrome (HUS) and are the main virulence factors of enterohemorrhagic Escherichia coli (EHEC). The bacterial SOS response is the essential signal for high level production and release of Stx1/2. To assess the potential effectiveness of different antibiotics in blocking SOS response and Stx1/2 production, we constructed a reporter gene based test system that allows for the time-resolved, simultaneous read-out of the SOS response (recAP-cfp) and Stx1 production (stx1::yfp) in EHEC O157:H7 EDL933. We find that cells exposed to inhibitory or subinhibitory concentrations of ciprofloxacin did induce the SOS response, but not when the cells were exposed to rifaximine, azithromycin, tetracycline, gentamicin or ampicillin. Cell lysis and the peak in Stx1 production were substantially delayed with respect to the peak of the SOS response. We used this feature to show that adding transcriptional or translational inhibitors can block Stx1 production even after the SOS response is fully induced. RT-qPCR based tests with other clinically relevant EHEC isolates showed similar results for both Stx1 and Stx2. These observations suggest that transcriptional and translational inhibitors may be of value in treating EHEC infections.

Consensus Report on Shigella Controlled Human Infection Model: Conduct of Studies

Shigella causes morbidity and mortality worldwide, primarily affecting young children living in low-resource settings. It is also of great concern due to increasing antibiotic resistance, and is a priority organism for the World Health Organization. A Shigella vaccine would decrease the morbidity and mortality associated with shigellosis, improve child health, and decrease the need for antibiotics. Controlled human infection models (CHIMs) are useful tools in vaccine evaluation for early up- or down-selection of vaccine candidates and potentially useful in support of licensure. Over time, the methods employed in these models have become more uniform across sites performing CHIM trials, although some differences in conduct persist. In November 2017, a Shigella CHIM workshop was convened in Washington, District of Columbia. Investigators met to discuss multiple aspects of these studies, including study procedures, clinical and immunological endpoints, and shared experiences. This article serves as a uniform procedure by which to conduct Shigella CHIM studies.

Guideline for the Antibiotic Use in Acute Gastroenteritis

Acute gastroenteritis is common infectious disease in community in adults. This work represents an update of 'Clinical guideline for the diagnosis and treatment of gastrointestinal infections' that was developed domestically in 2010. The recommendation of this guideline was developed regarding the following; epidemiological factors, test for diagnosis, the indications of empirical antibiotics, and modification of antibiotics after confirming pathogen. Ultimately, it is expected to decrease antibiotic misuse and prevent antibiotic resistance.

A Comparison of Stool Enteropathogen Detection by Semiquantitative PCR in Adults With Acute Travelers' Diarrhea Before and 3 Weeks After Successful Antibiotic Treatment

We evaluated stool enteropathogen detection by semiquantitative polymerase chain reaction (PCR) in 108 subjects with travelers’ diarrhea before and 3 weeks after treatment. Stool samples from 21 subjects were positive for the same pathogen species at both visits. We discuss factors that should be considered when interpreting stool PCR data after treatment.

Enterotoxigenic Escherichia coli Infections

PURPOSE OF REVIEW

Review recent developments pertaining to the epidemiology, molecular pathogenesis, and sequelae of enterotoxigenic Escherichia coli (ETEC) infections in addition to discussion of challenges for vaccinology.

RECENT FINDINGS

ETEC are a major cause of diarrheal illness in resource poor areas of the world where they contribute to unacceptable morbidity and continued mortality particularly among young children; yet, precise epidemiologic estimates of their contribution to death and chronic disease have been difficult to obtain. Although most pathogenesis studies, and consequently vaccine development have focused intensively on canonical antigens, more recently identified molecules unique to the ETEC pathovar may inform our understanding of ETEC virulence, and the approach to broadly protective vaccines. ETEC undeniably continue to have a substantial impact on global health; however, further studies are needed to clarify the true impact of these infections, particularly in regions where access to care may be limited. Likewise, our present understanding of the relationship of ETEC infection to non-diarrheal sequelae is presently limited, and additional effort will be required to achieve a mechanistic understanding of these diseases and to fulfill Koch's postulates on a molecular level. Precise elucidation of the role played by novel virulence factors, the global burden of acute illness, and the contribution of these pathogens and/or their toxins to non-diarrheal morbidity remain important imperatives.

Travelers' diarrhea: update on the incidence, etiology and risk in military and similar populations - 1990-2005 versus 2005-2015, does a decade make a difference?

BACKGROUND

Travelers' diarrhea remains a prevalent illness impacting individuals visiting developing countries, however most studies have focused on this disease in the context of short term travel. This study aims to determine the regional estimates of travelers' diarrhea incidence, pathogen-specific prevalence, and describe the morbidity associated with diarrheal disease among deployed military personnel and similar long term travelers.

METHODS

We updated a prior systematic review to include publications between January 1990 and June 2015. Point estimates and confidence intervals of travelers' diarrhea and pathogen prevalence were combined in a random effects model and assessed for heterogeneity. Eighty-two studies were included in the analysis, including 29 new studies since the prior systematic review.

RESULTS

Military personnel were evaluated in 69% of studies and non-military long term travelers in 34%, with a median duration of travel of 4.9 months, and travel predominantly to the Middle East, Southeast Asia, and Latin America and the Caribbean. Sixty-two percent of tested cases were due to bacterial pathogens, with enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), and Campylobacter predominating, and significant regional variability. The incidence of TD from studies with longitudinal data was 36.3 cases per 100 person-months, with the highest rates in Southeast Asia, Latin America and the Caribbean, and the Middle East, with higher estimates from those studies using self-reporting of disease. Morbidity remained significant, with 21% being incapacitated or placed sick in quarters (SIQ) by their illness, 15% requiring intravenous fluids, and 3% requiring hospitalization.

CONCLUSIONS

In comparison to results from the prior systematic review, there were no significant differences in incidence, pathogen prevalence, or morbidity; however there was a trend toward improved care-seeking by sick individuals.

Prescription of Antibiotics for Adults with Acute Infectious Diarrhea in Korea: A Population-based Study

Background

Acute infectious diarrhea (AID) is a commonly observed condition globally. Several studies recommend against the use of empiric antibiotic therapy for AID, except in some cases of travelers' diarrhea. However, many physicians prescribe antimicrobial agents for AID. We aimed to determine the rate of antibiotic use and the associated prescription patterns among adults with AID.

Materials and Methods

This population-based, retrospective epidemiological study was performed using Korean National Health Insurance claims data from 2016 to 2017. The study population comprised adults (age ≥18 years) who had visited clinics with AID-related complaints. Exclusion criteria were the presence of Crohn's disease, ulcerative colitis, irritable bowel syndrome, and other non-infectious forms of colitis. Patients who underwent surgery during admission were also excluded.

Results

The study population comprised 1,613,057 adult patients with AID (767,606 [47.6%] men). Young patients (age 18 – 39 years) accounted for 870,239 (54.0%) of the study population. Overall, 752,536 (46.7%) cases received antibiotic prescriptions. The rate of antibiotic administration tended to be higher among elderly patients (age ≥65 years) than among younger patients (49.5% vs. 46.4%, P <0.001). The antibiotics most frequently prescribed in both monotherapy and combination regimens were fluoroquinolones (29.8%), rifaximin (26.8%), second-generation cephalosporins (9.2%), third-generation cephalosporins (7.3%), trimethoprim/sulfamethoxazole (5.5%), and β-lactam/β-lactamase inhibitors (5.3%). Patients who visited tertiary care hospitals had lower rates of antibiotic therapy (n = 14,131, 41.8%) than did those visiting private clinics (n = 532,951, 47.1%). In total, 56,275 (62.3%) admitted patients received antibiotic therapy, whereas outpatients had lower rates of antibiotic prescription (n = 694,204, 46.0%).

Conclusion

This study revealed differences between the antibiotics used to treat AID in Korea and those recommended by the guidelines for AID treatment. Multifaceted efforts are necessary to strengthen physicians' adherence to published guidelines.

Comparison of stool collection and storage on Whatman FTA Elute cards versus frozen stool for enteropathogen detection using the TaqMan Array Card PCR assay

The use of Polymerase Chain Reaction (PCR) assays for pathogen detection in travelers' diarrhea (TD) field studies is limited by the on-site processing and storage requirements for fecal specimens. The objectives of this investigation were to i) characterize the pathogen distribution in deployed military personnel with TD using the TaqMan® Array Card PCR (TAC) on frozen stool and diarrheal smears on Whatman FTA Elute cards (FTA cards), and to ii) compare TAC detection of enteropathogen targets using smeared FTA cards and frozen stool, using TAC on frozen stool as the 'reference standard'. Stool samples, obtained from active duty personnel with acute TD enrolled in a field trial, were smeared onto FTA cards and stored at room temperature. A corresponding aliquot of stool was frozen in a cryovial. FTA cards and frozen stool samples were tested at a central lab, using a customized TAC for detection of TD pathogens. 187 paired frozen stool samples and smeared FTA cards were stored for a median of 712 days (IQR 396-750) before testing. Overall detection rates were 78.6% for frozen stool and 73.2% for FTA cards. Diarrheagenic Escherichia coli were the most common bacteria identified. Using the TAC results on frozen stool as the reference, the overall sensitivity and specificity of TAC on FTA cards was 72.9% and 98.0% respectively. TAC on FTA cards demonstrated a decrease in sensitivity with increasing frozen stool quantification cycle (Cq) (90.0% in FTA cards with a corresponding frozen stool Cq < 30, and 72.9% in samples with a corresponding frozen stool Cq < 35). Our findings support the use and further development of FTA cards in combination with a quantitative PCR assay for enteropathogen detection in TD field studies.

Infectious diseases during the European Union training mission Mali (EUTM MLI) - a four-year experience

BACKGROUND

The European Union Training Mission Mali (EUTM MLI) is a multinational military training deployment to the Western African tropical nation of Mali. Based on routinely collected disease and non-battle injury surveillance data, this study quantifies the true impact of infectious diseases for this tropical mission and potential seasonal variations in infectious disease threats.

METHODS

Categorized health events during the EUTM MLI mission and associated lost working days were reported using the EpiNATO-2 report. Infection-related health events were descriptively analyzed for a 4-year period from the 12th week in 2013 to the 13th week in 2017. Aggregated EpiNATO-2 data collected from all missions other than EUTM MLI were used as a comparator.

RESULTS

Among the infectious diseases reported by EUTM MLI, non-severe upper respiratory infections and gastrointestinal diseases dominated quantitatively, accounting for 1.65 and 1.42 consultations per 100 person-weeks, respectively. The number of recorded infectious disease-associated lost working days during the whole study interval was 723. Seasonal changes in disease frequency were detectable. More gastrointestinal infections were seen in the rainy season, and more respiratory infections occurred in the dry season; these were associated with peaks of more than 2.5 consultations per 100 person-weeks for both categories.

CONCLUSIONS

Despite initial concerns focused on tropical infectious diseases during this mission in tropical Mali, upper respiratory tract and gastrointestinal infections predominate. The relatively low number of reported lost working days may indicate that these infections are at the milder end of the spectrum of infectious diseases despite a likely reporting bias.

Rifamycin SV-MMX® for treatment of travellers' diarrhea: equally effective as ciprofloxacin and not associated with the acquisition of multi-drug resistant bacteria

BACKGROUND

The novel oral antibiotic formulation Rifamycin SV-MMX®, with a targeted delivery to the distal small bowel and colon, was superior to placebo in treating travellers' diarrhea (TD) in a previous study. Thus, a study was designed to compare this poorly absorbed antibiotic with the systemic agent ciprofloxacin.

METHODS

In a randomized double-blind phase 3 study (ERASE), the efficacy and safety of Rifamycin SV-MMX® 400 mg twice daily (RIF-MMX) was compared with ciprofloxacin 500 mg twice daily in the oral treatment of TD. Overall, 835 international visitors to India, Guatemala or Ecuador with acute TD were randomized to receive a 3-day treatment with RIF-MMX (n = 420) or ciprofloxacin (n = 415). Primary endpoint was time to last unformed stool (TLUS), after which clinical cure was declared. Stools samples for microbiological evaluation were collected at the baseline visit and the end of treatment visit.

RESULTS

Median TLUS in the RIF-MMX group was 42.8 h versus 36.8 h in the ciprofloxacin group indicating non-inferiority of RIF-MMX to ciprofloxacin (P = 0.0035). Secondary efficacy endpoint results including clinical cure rate, treatment failure rate, requirement of rescue therapy as well as microbiological eradication rate confirmed those of the primary analysis indicating equal efficacy for both compounds. While patients receiving ciprofloxacin showed a significant increase of Extended Spectrum Beta Lactamase Producing-Escherichia coli (ESBL-E. Coli) colonization rates after 3-days treatment (6.9%), rates did not increase in patients receiving RIF-MMX (-0.3%). Both drugs were well-tolerated and safe.

CONCLUSION

The novel multi-matrix formulation of the broad-spectrum, poorly absorbed antibiotic Rifamycin SV was found non-inferior to the systemic antibiotic ciprofloxacin in the oral treatment of non-dysenteric TD with the advantage of a lower risk of ESBL-E. Coli acquisition.

Strategies to Improve Management of Acute Watery Diarrhea during a Military Deployment: A Cost Effectiveness Analysis

To inform policy and decision makers, a cost-effectiveness model was developed to predict the cost-effectiveness of implementing two hypothetical management strategies separately and concurrently on the mitigation of deployment-associated travelers’ diarrhea (TD) burden. The first management strategy aimed to increase the likelihood that a deployed service member with TD will seek medical care earlier in the disease course compared with current patterns; the second strategy aimed to optimize provider treatment practices through the implementation of a Department of Defense Clinical Practice Guideline. Outcome measures selected to compare management strategies were duty days lost averted (DDL-averted) and a cost effectiveness ratio (CER) of cost per DDL-averted (USD/DDL-averted). Increasing health care and by seeking it more often and earlier in the disease course as a stand-alone management strategy produced more DDL (worse) than the base case (up to 8,898 DDL-gained per year) at an increased cost to the Department of Defense (CER $193). Increasing provider use of an optimal evidence-based treatment algorithm through Clinical Practice Guidelines prevented 5,299 DDL per year with overall cost savings (CER −$74). A combination of both strategies produced the greatest gain in DDL-averted (6,887) with a modest cost increase (CER $118). The application of this model demonstrates that changes in TD management during deployment can be implemented to reduce DDL with likely favorable impacts on mission capability and individual health readiness. The hypothetical combination strategy evaluated prevents the most DDL compared with current practice and is associated with a modest cost increase.

Management of Acute Diarrheal Illness During Deployment: A Deployment Health Guideline and Expert Panel Report

BACKGROUND

Acute diarrheal illness during deployment causes significant morbidity and loss of duty days. Effective and timely treatment is needed to reduce individual, unit, and health system performance impacts.

METHODS

This critical appraisal of the literature, as part of the development of expert consensus guidelines, asked several key questions related to self-care and healthcare-seeking behavior, antibiotics for self-treatment of travelers' diarrhea, what antibiotics/regimens should be considered for treatment of acute watery diarrhea and febrile diarrhea and/or dysentery, and when and what laboratory diagnostics should be used to support management of deployment-related travelers' diarrhea. Studies of acute diarrhea management in military and other travelers were assessed for relevance and quality. On the basis of this critical appraisal, guideline recommendations were developed and graded by the Expert Panel using good standards in clinical guideline development methodology.

RESULTS

New definitions for defining the severity of diarrhea during deployment were established. A total of 13 graded recommendations on the topics of prophylaxis, therapy and diagnosis, and follow-up were developed. In addition, four non-graded consensus-based statements were adopted.

CONCLUSIONS

Successful management of acute diarrheal illness during deployment requires action at the provider, population, and commander levels. Strong evidence supports that single-dose antimicrobial therapy is effective in most cases of moderate to severe acute diarrheal illness during deployment. Further studies are needed to address gaps in available knowledge regarding optimal therapies for treatment, prevention, and laboratory testing of acute diarrheal illness.