Aetiology of traveller's diarrhoea: evaluation of a multiplex PCR tool to detect different enteropathogens

Gut microbiota composition in travellers is associated with faecal lipocalin-2, a mediator of gut inflammation

Introduction

We examined the gut microbiota of travellers returning from tropical areas with and without traveller's diarrhoea (TD) and its association with faecal lipocalin-2 (LCN2) levels.

Methods

Participants were recruited at the Hospital Clinic of Barcelona, Spain, and a single stool sample was collected from each individual to perform the diagnostic of the etiological agent causing gastrointestinal symptoms as well as to measure levels of faecal LCN2 as a biomarker of gut inflammation. We also characterised the composition of the gut microbiota by sequencing the region V3-V4 from the 16S rRNA gene, and assessed its relation with the clinical presentation of TD and LCN2 levels using a combination of conventional statistical tests and unsupervised machine learning approaches.

Results

Among 61 participants, 45 had TD, with 40% having identifiable etiological agents. Surprisingly, LCN2 levels were similar across groups, suggesting gut inflammation occurs without clinical TD symptoms. Differential abundance (DA) testing highlighted a microbial profile tied to high LCN2 levels, marked by increased Proteobacteria and Escherichia-Shigella, and decreased Firmicutes, notably Oscillospiraceae. UMAP analysis confirmed this profile's association, revealing distinct clusters based on LCN2 levels. The study underscores the discriminatory power of UMAP in capturing meaningful microbial patterns related to clinical variables. No relevant differences in the gut microbiota composition were found between travellers with or without TD.

Discussion

The findings suggest a correlation between gut microbiome and LCN2 levels during travel, emphasising the need for further research to discern the nature of this relationship.

Rapid detection of gastrointestinal pathogens using a multiplex polymerase chain reaction gastrointestinal panel and its role in antimicrobial stewardship

OBJECTIVES

The FilmArray gastrointestinal panel (FAGIP) is widely used to detect infectious diarrhoea due to its outstanding sensitivity compared to conventional methods, but there is geographic variation, such as in the distribution of pathogens, among populations.

METHODS

This was a retrospective study that analysed patients with acute diarrhoea who underwent FAGIP tests from all age groups during 2022. We compared positive rates of FAGIP between paediatric (n = 245) and adult patients (n = 242) of different origins. The targeted therapy rate and antimicrobial agent use rate were also analysed.

RESULTS

Among the 487 stool samples evaluated, the overall, community-origin (CO), and nosocomial (NC) positivity rates of paediatric patients were significantly higher than those of adults (73.9 % vs. 43.0 %, p = 0.000; 76.2 % vs. 51.7 %, p = 0.000; 50.0 % vs. 19.7 %, p = 0.000). Salmonella was the most frequently detected pathogen (35.9 %) in children, while the predominant pathogen in adult patients was toxin A/B-genic Clostridioides difficile (13.2 %). There was a significantly lower antimicrobial agent use rate after FAGIP results were available (79.1 % vs. 64.5 %, p = 0.000) and a higher rate of targeted therapy towards C. difficile infection in adults than in children (84.4 % vs. 69.0 %, p = 0.011).

CONCLUSION

Paediatric diarrhoea patients showed higher positivity rates than adult patients. Application of FAGIP for acute diarrhoea might lower unnecessary antimicrobial use.

Increased Prevalence of Symptomatic Human Intestinal Spirochetosis in MSM with High-Risk Sexual Behavior in a Cohort of 165 Individuals

Human intestinal spirochetosis (HIS) can cause gastrointestinal symptoms, although asymptomatic infections have been described. Individuals from low-income countries, people living with HIV, and men who have sex with men (MSM) show increased risk. A retrospective review of all patients diagnosed with HIS (n = 165) between January 2013 and October 2020 at a tertiary hospital in Madrid, Spain, was performed to assess risk factors for symptomatic HIS, symptoms, and response to treatment. Most patients were male (n = 156; 94.5%), 86.7% were MSM, and 23.5% practiced chemsex, of whom most were symptomatic (p = 0.039). Most patients (78.4%) reported unprotected oral-anal intercourse. A total of 124 (81.1%) were symptomatic; diarrhea was the most common complaint (68.3%). Multivariable regression showed increased odds of symptoms associated with age under 41 (odds ratio 5.44, 95% CI 1.87-15.88; p = 0.002). Colonoscopy was normal in 153 (92.7%). Furthermore, 66.7% presented previous or concomitant sexually transmitted diseases (STDs). Among the patients, 102 underwent testing for other gastrointestinal pathogens, with positive results in 20 (19.6%). All symptomatic patients without concomitant gastrointestinal infection presenting improvement on follow-up (42 of 53) had received either metronidazole or doxycycline (p = 0.049). HIS should be considered as a cause of chronic diarrhea in MSM with high-risk sexual behavior after other causes have been ruled out; treatment with metronidazole is recommended. Coinfection with other STDs is common.

Shigellosis in Southeast Asia: A systematic review and meta-analysis

BACKGROUND

Southeast Asia is attractive for tourism. Unfortunately, travelers to this region are at risk of becoming infected with Shigella. We conducted a meta-analysis to provide updates on Shigella prevalence in Southeast Asia, along with their serogroups and serotypes.

METHODS

We conducted a systematic search using PubMed, EMBASE, and Web of Science for peer-reviewed studies from 2000 to November 2022. We selected studies that detected Shigella in stools by culture or polymerase chain reaction (PCR). Two reviewers extracted the data using a standardized form and performed quality assessments using the Joanna Briggs Institute checklist. The random effects model was used to estimate the pooled prevalence of Shigella.

RESULTS

During our search, we identified 4376 studies. 29 studies (from six Southeast Asian countries) were included in the systematic review, 21 each in the meta-analysis of the prevalence of Shigella (Sample size: 109545) and the prevalence of Shigella serogroups. The pooled prevalence of Shigella was 4% (95% CI: 4-5%) among diarrhea cases. Shigella sonnei was the most abundant serogroup in Thailand (74%) and Vietnam (57%), whereas Shigella flexneri was dominant in Indonesia (72%) and Cambodia (71%). Shigella dysenteriae and Shigella boydii were uncommon (pooled prevalence of 1% each). The pooled prevalence of Shigella was 5% (95% CI: 4-6%) in children aged <5 years. The pooled prevalence showed a decreasing trend comparing data collected between 2000-2013 (5%; 95% CI: 4-6%) and between 2014-2022 (3%; 95% CI: 2-4%). Shigella prevalence was 6% in studies that included participants with mixed pathogens versus 3% in those without. Shigella flexneri serotype 2a was the most frequently isolated (33%), followed by 3a (21%), 1b (10%), 2b (3%), and 6 (3%).

CONCLUSIONS

This study provides compelling evidence for the development of effective Shigella vaccines for residents of endemic regions and travellers to these areas.

Persistent abdominal symptoms in returning travellers: clinical and molecular findings

BACKGROUND

Persistent abdominal symptoms (PAS) are the leading cause of post-travel morbidity although there is a paucity of evidence concerning the aetiology of this condition. Recently molecular methods for protozoa detection in stool have been introduced. Herein, we describe the clinical aspects and the prevalence of gastrointestinal protozoa in returning travellers with PAS.

METHODS

From 2017 to 2019, clinical information and stool specimens from returning travellers with PAS were analysed for the presence of parasites using the Allplex-GI-Parasite-assay. Stool findings from symptomatic patients without a travel history were used as a comparator.

RESULTS

During the 2-year study, 203 stool specimens from returning travellers were analysed. The median duration of symptoms before seeking care was 6 months, the most common symptoms were fatigue (79.2%), abdominal pain (75.7%) and loose stool (70.8%).Most of travellers had returned from Asia (57.6%), mainly from the Indian-subcontinent and only 52.6% were backpackers. Altogether, 36.9% samples were positive for protozoa, with Blastocystis hominis being the most common (26.6%) in samples, followed by Dientamoeba fragilis (18.7%), Giardia lamblia (3.0%) and Cryptosporidium spp (0.5%). The former two were dominant in all regions. In all cases but one, G. lamblia was acquired, but one were acquired in the Indian subcontinent (odds ratios 16.9; 95% confidence intervals: 1.9-148.3). Entamoeba histolytica was not detected. The demographic characterization of the 1359 non-travellers was comparable with the travellers. Among them D. fragilis was the most common followed by B. hominis, which was significantly less frequent compared among the travellers (16.7% vs 26.6%, P < 0.001). Average Cycle threshold values for each stool parasites were comparable between the two groups.

CONCLUSION

Among returning travellers with PAS, more than one-third were positive for gastrointestinal protozoa. A low rate of giardia was found and no E. histolytica while B. hominis followed by D. fragilis were the dominant findings. Further studies are required to better understand the role of these protozoa in PAS.

Persistent abdominal symptoms: a persistently neglected topic in travel medicine

Persistent abdominal symptoms are a common complaint in returning travellers; yet, there is very sparse evidence to support the causes and potential aetiologies. New molecular stool-testing techniques and accurate clinical studies may shed light on this gap in our knowledge, paving ways for more successful management of this common and difficult problem.

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.

Review of the role of gastrointestinal multiplex polymerase chain reaction in the management of diarrheal illness

Acute and chronic diarrheal illness secondary to gastrointestinal infection is a significant cause of morbidity and mortality around the world. A cornerstone of management includes prompt diagnosis and appropriate treatment of culprit pathogens. Timely diagnosis can improve patient care, assist in infection control, and prevent disease outbreaks. Historical methods of diagnosis include traditional culture methods and stool analysis. These are limited by long turnaround time and inability to simultaneously assess multiple pathogens. The advent of multiplexed nucleic acid amplification tests first began with the Food and Drug Administration-approved respiratory virus multiplex polymerase chain reaction (PCR) panel in 2009, followed by gastrointestinal infections in 2013, and neurological infections in 2014. We conducted a review of current literature pertaining to the clinical utility of a gastrointestinal multiplex PCR in management of acute and chronic diarrhea in patients. To date, seven platforms approved by the US Food and Drug Administration are used in detection of various bacterial, viral, and parasitic causative organisms for diagnosis of gastrointestinal infections. The sensitivity and specificity of each assay vary depending on the tested organism. Interpretation of a positive result has to be tailored to the clinical context. Further studies are required to establish the utility of gastrointestinal multiplex PCR from a cost-based perspective, whether specific enteropathogens such as Clostridioides difficile are better assessed with toxin gene detection and whether new parameters such as cycle threshold values can improve clinical application of test results.

Improved diagnosis of gastrointestinal infections using a semi-automated multiplex real-time PCR for detection of enteropathogens

Introduction. The identification of enteropathogens is critical for the clinical management of patients with suspected gastrointestinal infection. The FLOW multiplex PCR system (FMPS) is a semi-automated platform (FLOW System, Roche) for multiplex real-time PCR analysis.Hypothesis/Gap Statement. FMPS has greater sensitivity for the detection of enteric pathogens than standard methods such as culture, biochemical identification, immunochromatography or microscopic examination.Aim.The diagnostic performance of the FMPS was evaluated and compared to that of traditional microbiological procedures.Methodology. A total of 10 659 samples were collected and analysed over a period of 7 years. From 2013 to 2018 (every July to September), samples were processed using standard microbiological culture methods. In 2019, the FMPS was implemented using real-time PCR to detect the following enteropathogens: Shigella spp., Salmonella spp., Campylobacter spp., Giardia intestinalis, Entamoeba histolytica, Blastocystis hominis, Cryptosporidum spp., Dientamoeba fragilis, adenovirus, norovirus and rotavirus. Standard microbiological culture methods (2013-2018) included stool culture, microscopy and immunochromatography.Results. A total of 1078 stool samples were analysed prospectively using the FMPS from July to September (2019): bacterial, parasitic and viral pathogens were identified in 15.3, 9.71 and 5.29 % of cases, respectively. During the same period of 6 years (2013-2018), the proportion of positive identifications using standard microbiological methods from 2013 to 2018 was significantly lower. A major significant recovery improvement was observed for all bacteria species tested: Shigella spp./enteroinvasive Escherichia coli (EIEC) (P <0.05), Salmonella spp. (P <0.05) and Campylobacter spp. (P <0.05). Marked differences were also observed for the parasites G. intestinalis, Cryptosporidium spp. and D. fragilis.Conclusion. These results support the value of multiplex real-time PCR analysis for the detection of enteric pathogens in laboratory diagnosis with outstanding performance in identifying labile micro-organisms. The identification of unsuspected micro-organisms for less specific clinical presentations may also impact on clinical practice and help optimize patient management.

Accuracy and comparison of two rapid multiplex PCR tests for gastroenteritis pathogens: a systematic review and meta-analysis

Objectives

The primary aim is to provide a summary of evidence for the diagnostic accuracies of multiplex PCR gastrointestinal (GI) panels—BioFire FilmArray and Luminex xTAG on the detection of gastroenteritis pathogens. The secondary aim is to compare the performance of these GI panels head to head.

Methods

A comprehensive search up to 1 December 2019 was conducted on PubMed, Embase, Ovid Medline and Web of Science for studies that used FilmArray or Luminex xTAG Gastrointestinal Pathogen Panel (GPP) for diagnosis of acute gastroenteritis. A summary of diagnostic accuracies for the 16 pathogens were calculated by comparing the GI panels to the current gold standards (conventional standard microbiology techniques such as culture or PCR for bacteria, PCR or enzyme immunoassay (EIA) for viruses, microscopy or EIA for parasite). Hierarchical summary receiver operating characteristic (HSROC) curve analysis, pretest and post-test probabilities were used for estimating the pathogen detection performance.

Results

A total of 11 studies with 7085 stool samples were eligible for analysis. Multiplex PCRs demonstrated high diagnostic accuracy, with specificity ≧0.98 and area under the ROC curve (AUROC) ≧0.97 for all the pathogens except for Yersinia enterocolitica (AUROC 0.91). The FilmArray panel demonstrated a higher sensitivity than xTAG GPP for most of the pathogens with the exception of Rotavirus A (xTAG GPP and FilmArray were both 0.93).

Conclusions

This is the first meta-analysis that is a head-to-head comparison examining the performance of the novel multiplex PCR-based tests Luminex xTAG GPP and FilmArray GI panel in detecting each pathogen. Point estimates calculated from eligible studies showed that both GI panels are highly accurate and may provide important diagnostic information for early identification of gastroenteritis. In addition, although FilmArray has higher sensitivity and post-test probability than xTAG GPP for most of the pathogens, how this will translate to a clinical setting remains unclear.

Bacterial, viral and parasitic pathogens analysed by qPCR: Findings from a prospective study of travellers' diarrhoea

BACKGROUND

The diagnostics of travellers' diarrhoea (TD) has been revolutionised by multiplex qPCR assays. While mostly of bacterial aetiology, viruses and parasites account for the disease among 10-20% of travellers. Despite this, prospective studies applying qPCR assays remain scarce that cover not only bacteria, such as the various diarrhoeagenic Escherichia coli (DEC), but also viral and parasitic pathogens.

METHOD

We analysed by qPCR pre- and post-travel stool samples of 146 Finnish travellers for bacterial, viral and parasitic pathogens: enteropathogenic (EPEC), enteroaggregative (EAEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC), and enteroinvasive (EIEC) E. coli; Shigella, Campylobacter, Salmonella, Yersinia and Vibrio cholerae; norovirus G1 and G2, rotavirus, enteroviruses, and sapovirus; and Giardia lamblia, Entamoeba histolytica, and Cryptosporidium. Symptoms and medication data during travel were collected by questionnaires.

RESULTS

We detected bacterial pathogens in 102/146 samples (69.9%; EAEC, EPEC, ETEC most common), viral ones in 13 (8.9%; norovirus most common), and parasitic ones in one (0.7%; Giardia). Noroviruses were associated with severe symptoms (23.5% versus non-severe 4.9%). In the TD group, 41.7% (5/12) of those with viral pathogens (vs. 13.3%; 11/83 without) took antibiotics.

CONCLUSION

Viral pathogens, particularly noroviruses, prevail in severe TD. The symptoms of viral disease are often severe and lead to unwarranted use of antibiotics.

A Cross-Sectional Cohort Study of Extended-Spectrum-Beta-Lactamase-Producing Enterobacterales in Patients with Traveler's Diarrhea

Patients with traveler's diarrhea (TD) can acquire extended-spectrum-beta-lactamase (ESBL)-producing members of the Enterobacterales (EPE) during travel to areas of endemicity. The aim of the present study was to investigate the prevalence and characteristics of EPE carriage in travelers from southern Sweden who were sampled for bacterial diagnostics of TD compared to those of EPE carriage 10 years ago. Clinical samples sent for culture of common causes of bacterial enterocolitis, if the referral stated foreign travel, were included in the study. Antimicrobial susceptibility testing was done according to the EUCAST disk diffusion test method. EPE strains were subjected to whole-genome sequencing (WGS). Eighty-four of 303 patients carried a total of 92 ESBL-producing members of the Enterobacterales The overall prevalence of EPE in tested samples was thus 28%, compared to 24% 10 years earlier (P = 0.33). Among 86 strains available for WGS, 47 different sequence types (STs) were identified, and there were only 5 ST131 strains. Of the 79 Escherichia coli isolates, 76% carried at least one fim (type 1 fimbria) gene, 29% carried at least one pap (p-fimbriae) gene, and 43% were extraintestinal pathogenic E. coli (ExPEC) or uropathogenic E. coli (UPEC). Over half of the E. coli strains (57%) were intestinal pathogenic E. coli, most commonly enteroaggregative E. coli (EAEC) (33%), and enteroinvasive E. coli EIEC (22%). A relatively high proportion of patients with traveler's diarrhea carry EPE, but there was no significant increase compared to 10 years ago. Most E. coli strains were intestinal pathogenic strains. A comparatively high proportion of the strains were ExPEC/UPEC, many expressing the virulence genes pap and/or fim (This project was assigned ClinicalTrials.gov number NCT03866291.).

Efficacy of stool multiplex polymerase chain reaction assay in adult patients with acute infectious diarrhea

BACKGROUND

Recently, stool multiplex polymerase chain reaction (PCR) tests have been developed for identifying diarrhea-causing bacterial pathogens. Furthermore, fecal calprotectin is a well-known effective marker for intestinal mucosal inflammation.

AIM

To evaluate the efficacy of stool multiplex PCR and fecal calprotectin in acute infectious diarrhea.

METHODS

Overall, 400 patients with acute infectious diarrhea were enrolled from Kangdong Sacred Heart Hospital (January 2016 to December 2018). Multiplex PCR detected 7 enteropathogenic bacteria including Salmonella, Campylobacter, Shigella, Escherichia coli O157:H7, Aeromonas, Vibrio, and Clostridium difficile. We reviewed clinical and laboratory findings using stool multiplex PCR.

RESULTS

Stool multiplex PCR test detected considerably more bacterial pathogens than stool culture (49.2% vs 5.2%), with Campylobacter as the most common pathogen (54%). Patients with positive stool PCR showed elevated fecal calprotectin expression compared to patients with negative stool PCR (1124.5 ± 816.9 mg/kg vs 609 ± 713.2 mg/kg, P = 0.001). C-reactive protein (OR = 1.01, 95%CI: 1.001-1.027, P = 0.034) and sigmoidoscopy-detected colitis (OR = 4.76, 95%CI: 1.101-20.551, P = 0.037) were independent factors in stool PCR-based detection of bacterial pathogens. Sensitivity and specificity of calprotectin were evaluated to be 70.5% and 60.9%, respectively (adjusted cut-off value = 388 mg/kg).

CONCLUSION

Stool multiplex PCR test has increased sensitivity in detecting pathogens than conventional culture, and it is correlated with calprotectin expression. Stool multiplex PCR and calprotectin may be effective in predicting clinical severity of infectious diarrhea.

Comparison of BioFire FilmArray gastrointestinal panel versus Luminex xTAG Gastrointestinal Pathogen Panel (xTAG GPP) for diarrheal pathogen detection in China

OBJECTIVES

To compare the performance of two syndromic panels: Luminex xTAG Gastrointestinal Pathogen Panel (GPP) and FilmArray Gastrointestinal (GI) panel.

METHODS

A total of 243 diarrhea specimens were detected by two panels in parallel, and the inconsistent results were analyzed by real-time PCR or reverse transcription PCR (RT-PCR). The target concentration in specimens was examined by comparing the crossing point values of FilmArray, the median fluorescence intensity of xTAG and the cycle threshold values in any discrepancies.

RESULTS

For pathogens detected by both panels, the positive rates of FilmArray GI and xTAG GPP were 65.0% and 48.6%, respectively. The two panels showed high consistency (kappa ≥0.74) in detecting norovirus, rotavirus and Campylobacter, while there was low consistency (kappa ≤0.40) in detecting Cryptosporidium, Salmonella, Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic Escherichia coli (ETEC). Samples with low concentration targets were more often detected by FilmArray than with xTAG GPP. The xTAG GPP was more likely to be affected by amplification inhibitors. Several defects of xTAG GPP were found in detecting ETEC.

CONCLUSIONS

FilmArray was more sensitive. For specimens with low target concentrations or containing ETEC heat stable enterotoxin, the false negatives of xTAG GPP need to be considered.

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.

Risk factors for different intestinal pathogens among patients with traveler's diarrhea: A retrospective analysis at a German travel clinic (2009-2017)

BACKGROUND

Travelers' diarrhea (TD) is the most common illness experienced by travelers to developing regions of the world and may be caused by bacterial, parasitic or viral pathogens. The available diagnostic tests include stool microscopy for parasitic infections, culture-dependent methods for bacterial infections and molecular methods for bacterial, parasitic and viral infections.

METHOD

We retrospectively evaluated demographic, clinical and microbiological data of patients presenting with TD at our travel clinic between 2009 and 2017.

RESULTS

Among 676 patients with TD included in our study, at least one etiologic agent was found in 21% (n = 145) of cases. In total, 195 enteropathogens were detected of which 110 were bacteria, 70 protozoa and 15 helminths. Bacterial infections were significantly more common when symptoms were present less than 14 days and travel duration did not exceed 29 days. Protozoa and helminths were predominantly detected in patients with longer lasting complaints. After stool culture was replaced by a multiplex-PCR gastrointestinal pathogen panel (GPP) at our center, significantly more intestinal bacterial pathogens were detected.

CONCLUSIONS

Our results support an individualized approach in the diagnostic workup of patients with TD taking host and travel characteristics into account to avoid unnecessary diagnostic testing. Molecular culture-independent diagnostic stool tests provide better coverage of the variety of etiological agents than traditional stool culture and have the benefit of rapid detection. However, the high sensitivity bears challenges differentiating colonization from infection.

Diagnostic Value of Platelet and Leukocyte Counts in the Differential Diagnosis of Fever in the Returning Traveler

Malaria, arbovirus infection and travelers' diarrhea are among the most common etiologies of fever after a stay in the tropics. Because the initial symptoms of these diseases often overlap, the differential diagnostic remains a challenge. The aim of this study was to establish the effectiveness of platelet and leukocyte counts in the differential diagnosis of fever in the returning traveler. Between 2013 and 2016, patients with a clinical suspicion of malaria, who had thick blood smears performed were retrospectively included. The microbiological etiology of each episode was established based on molecular detection in the case of arbovirus infection, the detection of pathogens in stool samples for diarrhea and other gastrointestinal symptoms and the thick and thin blood smear results for malaria. A total of 1,218 episodes were included. Malaria, arbovirus infection, and diarrhea and other gastrointestinal symptoms caused 102 (8.4%), 68 (5.6%), and 72 (5.9%) episodes, respectively. The median platelet counts in malaria episodes were 89 × 10⁹/L and thrombocytopenia (< 150,000 × 10⁹ platelets/L) yielded a 98% negative predictive value to predict malaria. The median leukocyte counts in arbovirus infection episodes were 3.19 × 10⁹/L and leucopenia (< 4 × 10⁹ leukocytes/L) yielded a 97.9% negative predictive value to predict arbovirus infections. Platelet and leukocyte counts were not significantly altered in episodes caused by diarrhea and other gastrointestinal symptoms. Initial platelet and leukocyte counts might be useful for the clinical differential diagnosis of fever in the returning traveler. Although these results are insufficient to establish a diagnosis, they should be considered in the initial clinical assessment.

New Tools to Test Stool: Managing Travelers' Diarrhea in the Era of Molecular Diagnostics

Travelers' diarrhea affects up to 60% of visitors to tropical and subtropical regions. Although symptoms are generally self-limited, some infections are associated with significant morbidity and occasional mortality. Newer molecular diagnostic techniques allow for highly sensitive, specific, and expeditious testing of a wide range of potential pathogens. Identification of the causative pathogen of travelers' diarrhea allows for targeted therapy and management and a reduction in empiric broad-spectrum coverage.

Giardia lamblia miRNAs as a new diagnostic tool for human giardiasis

Background

Giardia lamblia is a very common cause of gastrointestinal symptoms worldwide. There are several methods for the diagnosis of Giardia infection, however none are ideal. We aim to find a new, microRNA-based method that will improve the currently available diagnostic methods for giardiasis.

Methods

Deep-sequence profiling of Giardia small-RNA revealed that miR5 and miR6 are highly expressed in Giardia. These miRNAs were tested by qRT-PCR in duodenal biopsies of patients with giardiasis who were positive by microscopic pathological evaluation. The gastric biopsies of the same patients served as negative control tissues. Additionally, these miRNAs were evaluated in stool samples of patients with proven giardiasis.

Results

All histologically proven duodenal biopsies of patients with Giardia infection were positive for Giardia miR5, with a mean threshold cycle (Ct) of 23.7, as well as for Giardia DNA qPCR (16S-like gene, mean Ct 26.3). Gastric biopsies which were tested as a control all were negative. Stool evaluation of miR6 in patients with giardiasis showed 90% specificity but only 66% sensitivity, and a lower accuracy rate was obtained with miR5.

Conclusion

Giardia miR5 testing in duodenal biopsies may be a new method for the diagnosis of giardiasis. It seems to be more sensitive when compared with testing for Giardia DNA by qPCR in duodenal biopsies. It will be important to investigate the contribution of routine Giardia miRNA testing in duodenal biopsies from patients with persistent abdominal symptoms

Giardiasis is a major cause of diarrheal disease throughout the world. It is more common in areas with poor sanitation such as in many low-income countries, but it occurs in high-income countries as well. It is the most commonly identified intestinal parasite in the United States and it is endemic in other industrialized countries. The causative agent is the flagellate protozoan Giardia lamblia, and transmission is mainly by the fecal-oral route. The basic method of diagnosis is stool examination. It is usually found through stool microscopy examination which should be performed on fresh stool and repeated in 3 days. Despite some newer diagnostic methods, Giardia is still difficult to detect, often leading to misdiagnoses.

In this study we show that using Giardia microRNA (miR5) as a marker for Giardia infection in duodenal biopsies may be a new method for diagnosis of giardiasis. It appears to be more sensitive than histological diagnosis and also more sensitive than Giardia DNA testing in duodenal biopsies. Interestingly, in our patients, duodenal biopsies were done for persistent abdominal symptoms and the finding of Giardia in their biopsy was unexpected. Thus, testing duodenal biopsies for Giardia miRNA in patients with persistent abdominal symptoms might contribute to diagnosis and prompt treatment for those with giardiasis.

Burden and risk factors of Shigella sonnei shigellosis among children aged 0-59 months in hyperendemic communities in Israel

OBJECTIVES

Ultraorthodox Jewish populations living in towns with good sanitary infrastructure but with conditions of crowding have been the epicenter of Shigella sonnei shigellosis outbreaks. In this study, the incidence and risk factors of S. sonnei shigellosis in children living in an ultraorthodox community were determined.

METHODS

Data for the years 2000-2013 for all reported culture-proven S. sonnei shigellosis cases in children aged 0-59 months in the city of Elad were compared with data for the rest of the sub-district. Environmental factors obtained through parental interviews were evaluated for 78 incident cases of S. sonnei shigellosis and 141 community controls, matched by age, sex, and neighborhood. Conditional logistic regression models were performed.

RESULTS

Cyclic epidemics of S. sonnei shigellosis occurred every 2 years. The mean annual incidence was 10.0 per 1000 children in Elad (95% confidence interval 7.9-12.6) vs. 3.8 per 1000 children (95% confidence interval 3.3-4.4) in the sub-district (p<0.001). Concurrent diarrheal disease in family members, having the same person in the daycare center responsible for food handling and changing diapers, and more rooms and sinks in the center, were positively associated with S. sonnei shigellosis, while children's hand-washing before meals was inversely associated.

CONCLUSIONS

The burden of S. sonnei shigellosis in ultraorthodox communities is high. Enhanced hygiene interventions are required for epidemic control.

Emergence of Resistance to Quinolones and β-Lactam Antibiotics in Enteroaggregative and Enterotoxigenic Escherichia coli Causing Traveler's Diarrhea

The objective of this study was to assess the antimicrobial resistance of enteroaggregative Escherichia coli (EAEC) and enterotoxigenic E. coli (ETEC) strains causing traveler's diarrhea (TD) and to investigate the molecular characterization of antimicrobial resistance genes to third-generation cephalosporins, cephamycins, and quinolones. Overall, 39 EAEC and 43 ETEC clinical isolates were studied. The susceptibilities of EAEC and ETEC against ampicillin, amoxicillin-clavulanic acid, cefotaxime, imipenem, chloramphenicol, tetracycline, co-trimoxazole, nalidixic acid, ciprofloxacin, azithromycin, and rifaximin were determined. All genes encoding resistance determinants were detected by PCR or PCR plus DNA sequencing. The epidemiology of selected EAEC and ETEC strains was studied using multilocus sequence typing (MLST). The resistance to quinolones of EAEC and ETEC strains causing TD has significantly increased over the last decades, and high percentages have been found especially in patients traveling to India and sub-Saharan Africa. Sequence type 38 (ST38) and ST131, carrying the bla _CTX-M-15 and bla _CTX-M-27 genes, respectively, are highly prevalent among extended-spectrum β-lactamase (ESBL)-producing EAEC and ETEC strains. The cephamycinase ACT-20 is described in the present study for the first time in EAEC and ETEC strains causing TD in patients who had traveled to Central America. The percentages of resistance to azithromycin in EAEC and ETEC isolates from patients to Southeast Asia/India and Africa are above 25%. Meanwhile, rifaximin is still active against EAEC and ETEC, with the prevalence of resistant strains not being high. In conclusion, fluoroquinolones should no longer be considered the drugs of choice for the prevention or treatment in TD for travelers traveling to India and Africa. Azithromycin and rifaximin are still a good alternative to treat TD caused by EAEC or ETEC.

Cholera: under diagnosis and differentiation from other diarrhoeal diseases

BACKGROUND

Globally 1.4 billion people are at risk from cholera in countries where the disease is endemic, with an estimated 2.8 million cases annually. The disease is significantly under reported due to economic, social and political disincentives as well as poor laboratory resources and epidemiological surveillance in those regions. In addition, identification of cholera from other diarrhoeal causes is often difficult due to shared pathology and symptoms with few reported cases in travellers from Northern Europe.

METHODS

A search of PubMed and Ovid Medline for publications on cholera diagnosis from 2010 through 2017 was conducted. Search terms included were cholera, Rapid Diagnostic Test (RDT), multiplex PCR and diagnosis of diarrhoea. Studies were included if they are published in English, French or Spanish.

RESULTS

An increase of RDT study publications for diarrhoeal disease and attempted test validations were seen over the publication period. RDTs were noted as having varied selectivity and specificity, as well as associated costs and local resource requirements that can prohibit their use.

CONCLUSIONS

Despite opportunities to employ RDTs with high selectivity and specificity in epidemic areas, or in remote locations without access to health services, such tests are limited to surveillance use. This may represent a missed opportunity to discover the true global presence of Vibrio cholerae and its role in all cause diarrhoeal disease in underdeveloped countries and in travellers to those areas. The wider applicability of RDTs may also represent an opportunity in the wider management of traveller's diarrhoea.

Despite antibiotic treatment of travellers' diarrhoea, pathogens are found in stools from half of travellers at return

BACKGROUND

Among visitors to the (sub)tropics, 20-50% contract travellers' diarrhoea (TD) and 5-30% take antibiotics. While shortening the duration of illness, antimicrobials predispose to acquisition of multi-drug resistant bacteria. Therefore, liberal use is no longer advocated. Although antibiotics kill pathogens, no data support the view that they could prevent post-infectious sequelae. We investigated how antibiotic use for TD abroad impacts the pathogen findings at return.

MATERIALS AND METHODS

We revisited 456 travellers' clinical data and stool pathogens examined by qPCR for Salmonella, Yersinia, Campylobacter, Shigella, Vibrio cholerae and enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC) and enteroinvasive (EIEC) Escherichia coli.

RESULTS

Among travellers with TD, antibiotic users had pathogen-positive samples less frequently than non-users (50% versus 83%). The difference was significant for EPEC (23% versus 47%) and EAEC (27% versus 54%), but not ETEC (17% versus 26%) or the other pathogens. Shigella/EIEC was found more often among antibiotic users than non-users (4% versus 1%).

CONCLUSION

Despite antibiotic treatment of TD, half of the users still had stool pathogens at return, reflecting either antibiotic resistance of pathogens or recolonisation/reinfection while abroad. Treatment of TD with antibiotics during travel should not be interpreted to indicate eradication of pathogens.

Multiplex tests to identify gastrointestinal bacteria, viruses and parasites in people with suspected infectious gastroenteritis: a systematic review and economic analysis

BACKGROUND

Gastroenteritis is a common, transient disorder usually caused by infection and characterised by the acute onset of diarrhoea. Multiplex gastrointestinal pathogen panel (GPP) tests simultaneously identify common bacterial, viral and parasitic pathogens using molecular testing. By providing test results more rapidly than conventional testing methods, GPP tests might positively influence the treatment and management of patients presenting in hospital or in the community.

OBJECTIVE

To systematically review the evidence for GPP tests [xTAG^® (Luminex, Toronto, ON, Canada), FilmArray (BioFire Diagnostics, Salt Lake City, UT, USA) and Faecal Pathogens B (AusDiagnostics, Beaconsfield, NSW, Australia)] and to develop a de novo economic model to compare the cost-effectiveness of GPP tests with conventional testing in England and Wales.

DATA SOURCES

Multiple electronic databases including MEDLINE, EMBASE, Web of Science and the Cochrane Database were searched from inception to January 2016 (with supplementary searches of other online resources).

REVIEW METHODS

Eligible studies included patients with acute diarrhoea; comparing GPP tests with standard microbiology techniques; and patient, management, test accuracy or cost-effectiveness outcomes. Quality assessment of eligible studies used tailored Quality Assessment of Diagnostic Accuracy Studies-2, Consolidated Health Economic Evaluation Reporting Standards and Philips checklists. The meta-analysis included positive and negative agreement estimated for each pathogen. A de novo decision tree model compared patients managed with GPP testing or comparable coverage with patients managed using conventional tests, within the Public Health England pathway. Economic models included hospital and community management of patients with suspected gastroenteritis. The model estimated costs (in 2014/15 prices) and quality-adjusted life-year losses from a NHS and Personal Social Services perspective.

RESULTS

Twenty-three studies informed the review of clinical evidence (17 xTAG, four FilmArray, two xTAG and FilmArray, 0 Faecal Pathogens B). No study provided an adequate reference standard with which to compare the test accuracy of GPP with conventional tests. A meta-analysis (of 10 studies) found considerable heterogeneity; however, GPP testing produces a greater number of pathogen-positive findings than conventional testing. It is unclear whether or not these additional 'positives' are clinically important. The review identified no robust evidence to inform consequent clinical management of patients. There is considerable uncertainty about the cost-effectiveness of GPP panels used to test for suspected infectious gastroenteritis in hospital and community settings. Uncertainties in the model include length of stay, assumptions about false-positive findings and the costs of tests. Although there is potential for cost-effectiveness in both settings, key modelling assumptions need to be verified and model findings remain tentative.

LIMITATIONS

No test-treat trials were retrieved. The economic model reflects one pattern of care, which will vary across the NHS.

CONCLUSIONS

The systematic review and cost-effectiveness model identify uncertainties about the adoption of GPP tests within the NHS. GPP testing will generally correctly identify pathogens identified by conventional testing; however, these tests also generate considerable additional positive results of uncertain clinical importance.

FUTURE WORK

An independent reference standard may not exist to evaluate alternative approaches to testing. A test-treat trial might ascertain whether or not additional GPP 'positives' are clinically important or result in overdiagnoses, whether or not earlier diagnosis leads to earlier discharge in patients and what the health consequences of earlier intervention are. Future work might also consider the public health impact of different testing treatments, as test results form the basis for public health surveillance.

STUDY REGISTRATION

This study is registered as PROSPERO CRD2016033320.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Travellers' diarrhoea: Impact of TD definition and control group design on study results

BACKGROUND

Travellers' diarrhoea (TD) is a common health problem among visitors to the (sub)tropics. Much research deals with aetiology, prevention, and post-infection sequalae, yet the data may not allow comparisons due to incompatible definitions of TD and No TD control groups.

METHOD

The impact of defining TD and No TD control groups was explored by revisiting our recent data. We set up two TD groups: classical TD i.e. ≥3 loose or liquid stools/day and WHO TD (diarrhoea as defined by the WHO) i.e. any diarrhoea, and four No TD groups by TD definition and timing (no classical/WHO TD during travel, no ongoing classical/WHO TD).

RESULTS

TD was recorded for 37% versus 65% of subjects when using classical versus WHO definitions, respectively; the proportions of the various pathogens proved similar. The strictest criterion for the No TD control group (no WHO TD during travel) yielded pathogens among 61% and the least strict (no ongoing classical TD) among 73% of the travellers; the differences were greatest for enteroaggregative Escherichia coli and Campylobacter.

CONCLUSIONS

Definition of TD and control group design substantially impact on TD study results. The WHO definition yields more cases, but the pathogen selection is similar by both definitions. Design of the No TD control group was found critical: only those remaining asymptomatic throughout the journey should be included.

Navigating the jungles of tropical infectious gastrointestinal pathology: a pattern-based approach to the endoscopic biopsy

International travels and global human migration have had the unforeseen consequence of increasing the exposure of histopathologists in developed countries to the pathology of tropical infectious disease. The gastrointestinal tract (GIT) is often the primary site of infection due to the faecal-oral route of transmission and the high risk of exposure to contaminated water, food or soil when travelling to these regions. Whilst current microbiologic techniques are far more sensitive than histology in detecting infectious pathogens, the histopathologist nonetheless retains a pivotal role in diagnosing tropical GIT disease. This role entails evaluating endoscopic biopsies for any characteristic inflammatory pattern, identifying pathogens which may be present and excluding other look-alike pathologies. Recent advances in commercially available diagnostic modalities, including molecular techniques, have further broadened the scope of the histopathologist's armamentarium. This review outlines a practical pattern-based approach to diagnosing tropical GIT infections in endoscopic material, so as to assist pathologists less familiar with this spectrum of pathology.

Highly sensitive and specific detection of Giardia duodenalis, Entamoeba histolytica, and Cryptosporidium spp. in human stool samples by the BD MAX™ Enteric Parasite Panel

Detection of intestinal protozoan parasites by light microscopy is cumbersome, needs experienced personnel, and may lack sensitivity and/or specificity as compared with molecular-based stool assays. Here, we evaluated the BD MAX™ Enteric Parasite Panel, i.e., a multiplex real-time PCR assay for simultaneous detection of Giardia duodenalis, Entamoeba histolytica, and cryptosporidia (Cryptosporidium parvum and C. hominis), by examining 200 positive human stool samples (138 × G. duodenalis, 27 × E. histolytica, 35 × Cryptosporidium spp.) and 119 controls including 18 samples with E. dispar. The majority of the samples, i.e., 153/200 (76.5%) positive samples and 66/119 (55.5%) controls, were confirmed by multiplex in-house PCR detecting the same parasites as the BD MAX™ Enteric Parasite Panel. The BD MAX™ assay did not yield false-positive results. Sensitivity and specificity were 97.8% (95% CI, 93.3-99.4%) and 100% (95% CI, 97.4-100%) for G. duodenalis, 100% (95% CI, 84.5-100%) and 100% (95% CI, 98.4-100%) for E. histolytica, and 100% (95% CI, 87.7-100%) and 100% (95% CI, 98.3-100%) for cryptosporidia, and similar data were obtained when only the 219 PCR-confirmed samples were analyzed. Thus, the BD MAX™ Enteric Parasite Panel provides a highly sensitive and specific tool for the laboratory diagnosis of three predominant protozoan parasites causing enteritis.

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.

New molecular diagnostic tools in traveller's diarrhea

Traveller's diarrhea can be caused by bacteria, protozoa, helminths and viruses. Globally, the most common causes of traveller's diarrhea are two pathotypes of Escherichia coli (enterotoxigenic and enteroaggregative) and Shigella, although there are significant variations according to the geographic area visited. While traveller's diarrhea is usually a mild, self-limiting disease, half of the travellers with traveller's diarrhea have some limitation in their activities during the journey and up to 10% present persistent diarrhea or other complications, making microbiological diagnosis necessary. The aim of this article is to describe the application of new molecular diagnostic tools mainly based on multiplex PCR, including their advantages and disadvantages as well as the current gaps that requiring further study.

Guidelines for the prevention and treatment of travelers' diarrhea: a graded expert panel report

BACKGROUND

: Travelers' diarrhea causes significant morbidity including some sequelae, lost travel time and opportunity cost to both travelers and countries receiving travelers. Effective prevention and treatment are needed to reduce these negative impacts.

METHODS

: This critical appraisal of the literature and expert consensus guideline development effort asked several key questions related to antibiotic and non-antibiotic prophylaxis and treatment, utility of available diagnostics, impact of multi-drug resistant (MDR) colonization associated with travel and travelers' diarrhea, and how our understanding of the gastrointestinal microbiome should influence current practice and future research. Studies related to these key clinical areas were assessed for relevance and quality. Based on this critical appraisal, guidelines were developed and voted on using current standards for clinical guideline development methodology.

RESULTS

: New definitions for severity of travelers' diarrhea were developed. A total of 20 graded recommendations on the topics of prophylaxis, diagnosis, therapy and follow-up were developed. In addition, three non-graded consensus-based statements were adopted.

CONCLUSIONS

: Prevention and treatment of travelers' diarrhea requires action at the provider, traveler and research community levels. Strong evidence supports the effectiveness of antimicrobial therapy in most cases of moderate to severe travelers' diarrhea, while either increasing intake of fluids only or loperamide or bismuth subsalicylate may suffice for most cases of mild diarrhea. Further studies are needed to address knowledge gaps regarding optimal therapies, the individual, community and global health risks of MDR acquisition, manipulation of the microbiome in prevention and treatment and the utility of laboratory testing in returning travelers with persistent diarrhea.

Etiology of travellers' diarrhea

Eleven published studies of the etiology of travellers' diarrhea (TD) were reviewed define the etiology of TD and to exam newly developed technology such as Real-Time multiplex polymerase chain reaction (PCR) to identify multiple pathogens in one assay to define the cause of TD. Using PCR methods bacterial pathogens were found in 72% of patients acquiring diarrhea in Latin America and in 80% in travellers with illness acquired in Southeast Asia). In these studies, enterotoxigenic Escherichia coli as the predominant pathogen (42% in Latin America and 28% in Southeast Asia). Ciprofloxacin-resistant Campylobacter was commonly associated with TD in Southeast Asia. Multiplex PCR has improved the detection of enteropathogens and allowed better assessment returning travellers hospitalized with TD and those with persistent diarrhea.

xMAP Technology: Applications in Detection of Pathogens

xMAP technology is applicable for high-throughput, multiplex and simultaneous detection of different analytes within a single complex sample. xMAP multiplex assays are currently available in various nucleic acid and immunoassay formats, enabling simultaneous detection and typing of pathogenic viruses, bacteria, parasites and fungi and also antigen or antibody interception. As an open architecture platform, the xMAP technology is beneficial to end users and therefore it is used in various pharmaceutical, clinical and research laboratories. The main aim of this review is to summarize the latest findings and applications in the field of pathogen detection using microsphere-based multiplex assays.

[Traveller's diarrhoea]

Traveller's diarrhoea (TD) is acquired primarily through ingestion of food and drinks contaminated with pathogens that cause diarrhoea. They can be bacteria, protozoa, helminths, and viruses. Globally, the most common causes of TD are two pathotypes of Escherichia coli (enterotoxigenic and enteroaggregative) and Campylobacter, although there are significant variations by geographic area visited. Most TD occurs in individuals traveling to low-middle income countries. The type of travel, length of stay, traveller's age, and the presence of certain underlying conditions are important risk factors to consider for the acquisition of TD. While TD is usually a mild and self-limiting disease, half of travellers with TD experience some limitation of activities during their trip, while up to 10% will experience persistent diarrhoea or other complications. The purpose of this article is to provide an updated microbiological, epidemiological, and clinical profile of traveller's diarrhoea, including known risk factors, as well as to make recommendations on the prevention and treatment of TD.

Enteroaggregative Escherichia coli in Daycare-A 1-Year Dynamic Cohort Study

Enteroaggregative Escherichia coli (EAEC) has been associated with persistent diarrhea, reduced growth acceleration, and failure to thrive in children living in developing countries and with childhood diarrhea in general in industrialized countries. The clinical implications of an EAEC carrier-status in children in industrialized countries warrants clarification. To investigate the pathological significance of an EAEC carrier-state in the industrialized countries, we designed a 1-year dynamic cohort study and performed follow-up every second month, where the study participants submitted a stool sample and answered a questionnaire regarding gastrointestinal symptoms and exposures. Exposures included foreign travel, consumption of antibiotics, and contact with a diseased animal. In the capital area of Denmark, a total of 179 children aged 0–6 years were followed in a cohort study, in the period between 2009 and 2013. This is the first investigation of the incidence and pathological significance of EAEC in Danish children attending daycare facilities. Conventional microbiological detection of enteric pathogens was performed at Statens Serum Institute, Copenhagen, Denmark, and at Hvidovre Hospital, Copenhagen, Denmark. Parents completed questionnaires regarding gastrointestinal symptoms. The EAEC strains were further characterized by serotyping, phylogenetic analysis, and susceptibility testing. EAEC was detected in 25 (14%) of the children during the observational period of 1 year. One or more gastrointestinal symptoms were reported from 56% of the EAEC-positive children. Diarrhea was reported in six (24%) of the EAEC positive children, but no cases of weight loss, and general failure to thrive were observed. The EAEC strains detected comprised a large number of different serotypes, confirming the genetic heterogeneity of this pathotype. EAEC was highly prevalent (n = 25, 14%) in Danish children in daycare centers and was accompanied by gastrointestinal symptoms in 56% of the infected children. No serotype or phylogenetic group was specifically linked to children with disease.

Small Intestinal Infections

Small intestinal infections are extremely common worldwide. They may be bacterial, viral, or parasitic in etiology. Most are foodborne or waterborne, with specific etiologies differing by region and with diverse pathophysiologies. Very young, very old, and immune-deficient individuals are the most vulnerable to morbidity or mortality from small intestinal infections. There have been significant advances in diagnostic sophistication with the development and early application of molecular diagnostic assays, though these tests have not become mainstream. The lack of rapid diagnoses combined with the self-limited nature of small intestinal infections has hampered the development of specific and effective treatments other than oral rehydration. Antibiotics are not indicated in the absence of an etiologic diagnosis, and not at all in the case of some infections.

Application of a multiplex PCR assay for the detection of gastrointestinal pathogens in a rural African setting

BACKGROUND

Despite high morbidity and mortality, the laboratory diagnosis of gastrointestinal infections is largely neglected in tropical African settings. This study aims to apply the Luminex multiplex PCR assay for the diagnosis of gastrointestinal pathogens in rural Ghana to evaluate its usefulness as a routine method.

METHODS

A case-control study was conducted at the Agogo Presbyterian Hospital in Ghana. Stool samples were collected from children below 6 years of age with (cases) and without (controls) diarrhoea. Samples were screened for 15 different diarrhoeal pathogens by the Luminex xTAG GPP assay and associations between diarrhoea and gastrointestinal infections and fractions attributable to diarrhea (AF) were determined.

RESULTS

The Luminex PCR assay identified organisms in 96.6% (n = 428) of 443 cases and in 92.5% (n = 221) of 239 selected controls. A mean of 2.5 (standard deviation [SD]: ± 1.3) and 2.3 (SD: ± 1.3) organisms per sample were detected in cases and controls respectively. An association with diarrhoea was found for rotavirus (adjusted odds ratio [aOR] = 7.2; 95% confidence interval [CI]: 2.9-18.1), norovirus (aOR = 2.7; 95% CI: 1.4-5.3) and Shigella spp. (aOR = 1.7; 95% CI: 1.2-2.4) with respective AFs of 12.5% (95% CI: 9.6-15.3), 7.9% (95% CI: 3.8-11.7) and 16.9% (95% CI: 6.9-25.9).

CONCLUSION

The high proportion of pathogen-positive stool samples with a high number of co-infections in cases and controls suggests a substantial amount of transient or colonizing microorganisms for which treatment is not necessarily implicated. The use of sequential diagnostic algorithms with pathogen specific or quantitative PCRs might be most appropriate for diagnosing gastrointestinal infections.

Advanced PCR-based molecular diagnosis of gastrointestinal infections: challenges and opportunities

Acute infections of the gastrointestinal tract are among the most common infectious diseases. The etiological agents of gastroenteritis may be bacteria, viruses or protozoa. Identification of the etiological agents of acute diarrhea is important for the treatment and management of diarrheal diseases. Conventional stool culture for bacteria shows a low sensitivity and requires more than 24 hours. In addition, other approaches to detect viruses and protozoa mainly involve antigen detection, but this is not available for all enteropathogens, and microscopic observation requires training and is of low sensitivity. In this review, the authors describe currently available molecular methods to detect different enteropathogens and analyze the main advantages and disadvantages of these methods for laboratory diagnosis of gastroenteritis.

[Malaria and intestinal protozoa]

Malaria is life threatening and requires urgent diagnosis and treatment. Incidence and mortality are being reduced in endemic areas. Clinical features are unspecific so in imported cases it is vital the history of staying in a malarious area. The first line treatments for Plasmodium falciparum are artemisinin combination therapies, chloroquine in most non-falciparum and intravenous artesunate if any severity criteria. Human infections with intestinal protozoa are distributed worldwide with a high global morbid-mortality. They cause diarrhea and sometimes invasive disease, although most are asymptomatic. In our environment populations at higher risk are children, including adopted abroad, immune-suppressed, travelers, immigrants, people in contact with animals or who engage in oral-anal sex. Diagnostic microscopic examination has low sensitivity improving with antigen detection or molecular methods. Antiparasitic resistances are emerging lately.

Evaluation of the xTAG Gastrointestinal Pathogen Panel Assay for the Detection of Enteric Pathogens in Kuwait

OBJECTIVE

To evaluate the utility of the Luminex xTAG gastrointestinal pathogen panel (GPP) assay in the detection of enteric pathogens from diarrheal stool samples in Kuwait.

MATERIALS AND METHODS

The Luminex xTAG GPP assay was used according to the manufacturer's instructions to evaluate single diarrheal stool samples from 109 hospitalized patients at Mubarak Al-Kabeer Hospital, Kuwait, from March 2014 to June 2015. The assay procedure involved nucleic acid extraction from stool samples, amplification of the target by reverse transcriptase polymerase chain reaction, hybridization of the amplified target by probe, detection of the target by the Luminex instrument and computerized data analysis. Conventional microbiological assays were used as the gold standard for comparison.

RESULTS

From the 109 diarrheal stool samples, 20 (18.4%) pathogens were detected by the xTAG GPP assay compared to 10 (9.2%) pathogens using conventional assays. Both methods detected 3 Salmonella spp., 3 Clostridium difficile, 2 rotavirus and 2 norovirus. In addition, the xTAG GPP assay detected 1 Shigella sp., 6 Campylobacter spp., 1 Cryptosporidium sp. and 2 Giardia lamblia which were missed by conventional assays.

CONCLUSIONS

In this study, xTAG GPP detected twice as many pathogens as the conventional assays. We recommend the introduction of this assay in routine diagnostic laboratories for a rapid and better diagnosis and treatment of diarrheal disease.

Metagenomic diagnostics for the simultaneous detection of multiple pathogens in human stool specimens from Côte d'Ivoire: a proof-of-concept study

BACKGROUND

The intestinal microbiome is a complex community and its role in influencing human health is poorly understood. While conventional microbiology commonly attributes digestive disorders to a single microorganism, a metagenomic approach can detect multiple pathogens simultaneously and might elucidate the role of microbial communities in the pathogenesis of intestinal diseases. We present a proof-of-concept that a shotgun metagenomic approach provides useful information on the diverse composition of intestinal pathogens and antimicrobial resistance profiles in human stool samples.

METHODS

In October 2012, we obtained stool specimens from patients with persistent diarrhea in south Côte d'Ivoire. Four stool samples were purposefully selected and subjected to microscopy, multiplex polymerase chain reaction (PCR), and a metagenomic approach. For the latter, we employed the National Center for Biotechnology Information nucleotide database and screened for 36 pathogenic organisms (bacteria, helminths, intestinal protozoa, and viruses) that may cause digestive disorders. We further characterized the bacterial population and the prevailing resistance patterns by comparing our metagenomic datasets with a genome-specific marker database and with a comprehensive antibiotic resistance database.

RESULTS

In the four patients, the metagenomic approach identified between eight and 11 pathogen classes that potentially cause digestive disorders. For bacterial pathogens, the diagnostic agreement between multiplex PCR and metagenomics was high; yet, metagenomics diagnosed several bacteria not detected by multiplex PCR. In contrast, some of the helminth and intestinal protozoa infections detected by microscopy were missed by metagenomics. The antimicrobial resistance analysis revealed the presence of genes conferring resistance to several commonly used antibiotics.

CONCLUSIONS

A metagenomic approach provides detailed information on the presence and diversity of pathogenic organisms in human stool samples. Metagenomic studies allow for in-depth molecular characterization such as the antimicrobial resistance status, which may be useful to develop setting-specific treatment algorithms. While metagenomic approaches remain challenging, the benefits of gaining new insights into intestinal microbial communities call for a broader application in epidemiologic studies.

TRIAL REGISTRATION

ISRCTN86951400.

Interventions for post-infectious irritable bowel syndrome: a systematic review of treatment efficacy

Background

Post-infectious irritable bowel syndrome (PI-IBS) due to traveler’s diarrhea is the second most common illness seen in post-travel clinics, yet its optimal management remains unknown. We performed a systematic review to evaluate treatment efficacy in PI-IBS.

Methods

We searched Medline, EMBASE, LILACS, CINAHL, CAB abstracts, and the Cochrane Library to February 3, 2014 for intervention studies of the pharmacologic and non-pharmacologic management of PI-IBS and examined the evidence according to a modified Grading of Recommendations Assessment, Development, and Evaluation (GRADE) scale.

Results

Of 336 records, 9 studies were included. Eight studies of pharmacologic interventions examined 5 agents (mesalazine or mesalamine, ondansetron, prednisolone, cholestyramine, and metronidazole). One study examined the non-pharmacologic intervention of different infant nutritional formulas following acute gastroenteritis. The quality of the evidence to date was low, with small sample size (fewer than 50 participants) and short duration of follow-up. Overall, the efficacy of pharmacological treatment ranged from no benefit (ondansetron and prednisolone) to moderately beneficial (cholestyramine and metronidazole). The evidence for mesalazine was equivocal: one study showed benefit, two others showed none.

Conclusions

Heterogeneity in outcome measures and low strength of evidence preclude recommendations on the optimal management of PI-IBS by a specific agent. More comparative intervention research into PI-IBS treatment is needed for consistent best practice in PI-IBS management. Clinicians may elect to pursue therapeutic trials of mesalazine, cholestyramine, or metronidazole in individual patients, but should be aware that data supporting the efficacy of these agents is limited.

Electronic supplementary material

The online version of this article (doi:10.1186/s40794-015-0002-9) contains supplementary material, which is available to authorized users.

Multiplex polymerase chain reaction tests for detection of pathogens associated with gastroenteritis

A wide range of enteric pathogens can cause infectious gastroenteritis. Conventional diagnostic algorithms are time-consuming and often lack sensitivity and specificity. Advances in molecular technology have provided new clinical diagnostic tools. Multiplex polymerase chain reaction (PCR)-based testing has been used in gastroenterology diagnostics in recent years. This article presents a review of recent laboratory-developed multiplex PCR tests and current commercial multiplex gastrointestinal pathogen tests. It focuses on two commercial syndromic multiplex tests: Luminex xTAG Gastrointestinal Pathogen Panel and BioFire FilmArray gastrointestinal test. Multiplex PCR tests have shown superior sensitivity to conventional methods for detection of most pathogens.

Metabolomics study of metabolic variations in enterotoxigenic Escherichia coli-infected piglets

This study aimed to explore the metabolic profiling in the serum of enterotoxigenic Escherichia coli (ETEC) infected piglets.