Travel-related acquisition of diarrhoeagenic bacteria, enteral viruses and parasites in a prospective cohort of 98 Dutch travellers

No evidence of pathogenicity of Dientamoeba fragilis following detection in stools: A case-control study

Dientamoeba fragilis is a ubiquitous intestinal parasite with detection in the stools that has become increasingly frequent following the advent of PCR as a routine screening tool. However, the pathogenicity of this parasite is still much debated. In order to assess the potentially pathogenic nature of this protozoan, a retrospective case-control study was carried out between January and December 2020 on patients from Toulouse University Hospital, with the aim of evaluating the potential clinical effects and changes in laboratory parameters linked to the presence and load of D. fragilis in stools. After matching age, sex and mode of care (consultation or hospitalisation), no significant difference was observed in the frequency of clinical signs between the 36 patients who tested positive for Dientamoeba fragilis PCR in their stools and the 72 control patients who were PCR negative for this protozoan. The presence of D. fragilis in the faeces was not associated with changes in laboratory parameters. Furthermore, a high digestive load of D. fragilis had no identifiable impact on clinical and laboratory parameters. Only the concomitant presence of Blastocystis sp. in stools was significantly more frequent in the D. fragilis group (uni- and multivariate analysis). Finally, this study showed no significant difference in clinical or laboratory signs between patients carrying Dientamoeba fragilis and the control group, regardless of the intestinal parasite load, suggesting that D. fragilis could be considered a commensal of the digestive tract.

Epidemiology of Blastocystis Infection: A Review of Data from Poland in Relation to Other Reports

Blastocystis is a common gut protist of humans and various animals worldwide, with a high level of genetic diversity. Neither its zoonotic potential and transmission routes nor its pathogenicity are fully known. This fact, and the fact that Blastocystis is the most abundant eukaryote in human faeces, raises the question of its relevance to public health. Here, we summarise (in relation to other reports) the results of studies on the prevalence and genotypic variation of Blastocystis, which were carried out in animals, humans, and in water environments in Poland. In humans, the prevalence ranged between 0.14 and 23.6%, in some animals reached 58.97%, and in water environments was 5.1%. Seven subtypes were identified in humans (ST1-ST4, ST6, ST7, and ST9), of which ST3 was the most common. Among animals (wild, livestock, and pet animals), eleven STs were identified, with differential host specificity. Humans and animals shared ST1, ST2, ST3, ST6, and ST7, while ST1 and ST3 were present in humans, animals, and water sources. These observations indicate the possibility of Blastocystis transmission between animals and humans. Further studies should be continued in search of the sources and transmission routes of Blastocystis in order to prevent the spread of infections among humans and animals.

Symptoms and PCR testing interval for bacterial pathogens in patients with diarrhoea

Introduction . Acute diarrhoea can be caused by Salmonella species, Shigella species, Yersinia enterocolitica, Campylobacter species and Plesiomonas shigelloides (SSYCP). In clinical practice, however, polymerase chain reaction (PCR) for SSYCP is frequently performed as part of the diagnostic work-up for patients with chronic diarrhoea and gastrointestinal complaints.Hypothesis. This study postulates that PCR for SSYCP is of limited clinical use in patients with chronic diarrhoea and gastrointestinal complaints.Aim. The primary aim of this study is to evaluate whether testing for SSYCP remains sensible in patients with chronic diarrhoea and gastrointestinal symptoms and if earlier testing leads to more positive PCR results.Methodology. Between January 2017 and December 2018, data on PCR results, culture results, symptoms, symptom to testing interval (STI) and immune status were retrospectively collected from the medical records of patients with gastrointestinal symptoms for whom PCR results for SSYCP were available. The STIs of PCR-positive patients and PCR-negative patients were compared.Results. In total, 146 PCR-positive and 149 PCR-negative patients were included. STIs of <7 days occurred in 55 % of all PCR-positive patients compared to 38 % in PCR-negative patients. PCR-positive patients were more often tested within 7 days after onset of gastrointestinal symptoms or diarrhoea. A third of PCR-positive patients had an STI of >7 days. Immunocompromised patients had a shorter STI. Admitted patients had a shorter STI. Eighty-six PCR-positive patients had a positive culture (58 %). Antibiotic use 3 months prior to PCR testing was correlated with negative PCR results.Conclusions . This study shows that early testing correlates with more positive PCR results and underlines that PCR for SSYCP is of lesser importance in the diagnostic workup of chronic diarrhoea and/or gastrointestinal symptoms. The shorter STI found in immunocompromised patients is possibly due to a lower threshold for testing in this population. It is also important to take recent antibiotic use into consideration when interpreting PCR results, given the correlation between negative PCR results and antibiotic use. Careful and precise documentation of symptoms in medical records is essential for clinical practice and research.

Intestinal Microbiota in Children With Symptomatic Dientamoeba fragilis Infection: A Case-control Study

BACKGROUND

Dientamoeba fragilis in children has been associated with gastrointestinal symptoms, like abdominal pain and diarrhea. The mechanism underlying these symptoms in children with D. fragilis remains unclear. We hypothesized that concomitant microbial alterations, which have been described in other parasitic infections, may be associated with gastrointestinal symptoms in D. fragilis.

METHODS

In this case-control study performed in 2 centers, 19 children referred to a pediatrician because of gastrointestinal symptoms and with a positive fecal PCR for D. fragilis were included as cases. We included 19 healthy children as controls and matched for age and gender, selected from an existing cohort of 63 children. A PCR for D. fragilis was performed on fecal samples of the 19 controls to assess D. fragilis carriership in this asymptomatic group. Microbiota was analyzed with the IS-pro technique, and the intestinal microbiota composition and diversity were compared between the 2 groups.

RESULTS

Microbiota of children with D. fragilis and gastrointestinal symptoms did not significantly differ in terms of composition and diversity compared with controls, both on phylum and species level. In the asymptomatic controls, a positive fecal PCR for D. fragilis was found in 16 of 19 (84.2%).

CONCLUSION

Intestinal microbiota does not seem to play a key role in the presence of clinical symptoms in children with D. fragilis. The pathogenicity of D. fragilis and pathophysiologic pathways underlying the development of gastrointestinal symptoms remains yet to be clarified.

Integrative Transkingdom Analysis of the Gut Microbiome in Antibiotic Perturbation and Critical Illness

Bacterial microbiota play a critical role in mediating local and systemic immunity, and shifts in these microbial communities have been linked to impaired outcomes in critical illness. Emerging data indicate that other intestinal organisms, including bacteriophages, viruses of eukaryotes, fungi, and protozoa, are closely interlinked with the bacterial microbiota and their host, yet their collective role during antibiotic perturbation and critical illness remains to be elucidated. We employed multi-omics factor analysis (MOFA) to systematically integrate the bacterial (16S rRNA), fungal (intergenic transcribed spacer 1 rRNA), and viral (virus discovery next-generation sequencing) components of the intestinal microbiota of 33 critically ill patients with and without sepsis and 13 healthy volunteers. In addition, we quantified the absolute abundances of bacteria and fungi using 16S and 18S rRNA PCRs and characterized the short-chain fatty acids (SCFAs) butyrate, acetate, and propionate using nuclear magnetic resonance spectroscopy. We observe that a loss of the anaerobic intestinal environment is directly correlated with an overgrowth of aerobic pathobionts and their corresponding bacteriophages as well as an absolute enrichment of opportunistic yeasts capable of causing invasive disease. We also observed a strong depletion of SCFAs in both disease states, which was associated with an increased absolute abundance of fungi with respect to bacteria. Therefore, these findings illustrate the complexity of transkingdom changes following disruption of the intestinal bacterial microbiome.

IMPORTANCE While numerous studies have characterized antibiotic-induced disruptions of the bacterial microbiome, few studies describe how these disruptions impact the composition of other kingdoms such as viruses, fungi, and protozoa. To address this knowledge gap, we employed MOFA to systematically integrate viral, fungal, and bacterial sequence data from critically ill patients (with and without sepsis) and healthy volunteers, both prior to and following exposure to broad-spectrum antibiotics. In doing so, we show that modulation of the bacterial component of the microbiome has implications extending beyond this kingdom alone, enabling the overgrowth of potentially invasive fungi and viruses. While numerous preclinical studies have described similar findings in vitro, we confirm these observations in humans using an integrative analytic approach. These findings underscore the potential value of multi-omics data integration tools in interrogating how different components of the microbiota contribute to disease states. In addition, our findings suggest that there is value in further studying potential adjunctive therapies using anaerobic bacteria or SCFAs to reduce fungal expansion after antibiotic exposure, which could ultimately lead to improved outcomes in the intensive care unit (ICU).

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.

Surveillance of enteropathogenic bacteria, protozoa and helminths in travellers returning from the tropics

Diarrhoea is a frequent symptom associated with travelling to tropical regions, but the cause is often not found. Epidemiology was assessed including up-to-date real-time PCR approaches.We analysed datasets of 528 patients who presented at the Bernhard Nocht Institute for Tropical Medicine in Hamburg, Germany, between 2006 and 2010 for screening purposes or because of diarrhoea. Stool samples were obtained and investigated by microscopy, bacterial culture, two PCR assays targeting Entamoeba histolytica, Entamoeba dispar, Giardia duodenalis, and Cryptosporidium parvum, or Salmonella spp., Shigella/EIEC spp., Campylobacter jejuni, and Yersinia spp.Among patients with gastrointestinal symptoms, 51% tested positive for bacteria or parasites, of which 66% had a known enteropathogenic potential. In patients without diarrhoea, 53% (n = 80) were positive, and 33% of these cases harboured agents of pathogenic potential. Association with clinical symptoms was primarily found for bacterial infections. Blastocystis hominis, however, was more frequent in asymptomatic than in symptomatic travellers.In conclusion, the study stresses the etiological relevance of bacterial gastroenteritis in travellers returning from the tropics, the need for molecular approaches to increase diagnostic sensitivity and demonstrates that asymptomatic carriage of enteropathogens after prolonged stays in the tropics is similarly frequent compared with symptomatic infections in travellers.

Risk factors for acquisition of multidrug-resistant Enterobacterales among international travellers: a synthesis of cumulative evidence

BACKGROUND

Recent studies have shown that over 50% of people travelling to Southeast Asia return colonized with multidrug-resistant Enterobacterales (MRE) including carbapenemase-producing Enterobacterales. Importation of MRE by travellers and subsequent spread to family members, communities and healthcare facilities poses real risks that have not yet been adequately assessed. This systematic review and meta-analysis aims to quantify the risk factors and interventions for reducing the risk of MRE acquisition among international travellers.

METHODS

A systematic search was conducted in PubMed, Web of Science and Scopus for analytical epidemiological studies containing data post-2000 that assessed the risk factors to acquire and/or interventions to reduce the risk of MRE acquisition in travellers. Two researchers independently screened all the studies and extracted the information, and disagreements were resolved through consensus. The proportions of MRE acquisition by the region of destination and the odds ratio (OR) for the different risk factors and/or interventions were pooled using the inverse variance heterogeneity model.

RESULTS

A total of 20 studies (5253 travellers from high-income countries) were included in the meta-analysis. South Asia [58.7%; 95% confidence interval (CI), 44.5-72.5%] and Northern Africa (43.9%; 95% CI 37.6-50.3%) were the travel destinations with the highest proportion of MRE acquisition. Inflammatory bowel disease (OR 2.1; 95% CI 1.2-3.8), use of antibiotics (OR 2.4; 95% CI 1.9-3.0), traveller's diarrhoea (OR 1.7; 95% CI 1.3-2.3) and contact with the healthcare system overseas (OR 1.5; 95% CI 1.1-2.2) were associated with MRE colonization. Vegetarians (OR 1.4; 95% CI 1.0-2.0) and backpackers (OR 1.5; 95% CI 1.2-1.8) were also at increased odds of MRE colonization. Few studies (n = 6) investigated preventive measures and found that consuming only bottled water/beverages, meticulous hand hygiene and probiotics had no protective effect on MRE colonization.

CONCLUSIONS

International travel is an important driver for MRE spread worldwide. Future research needs to identify effective interventions to reduce the risk of MRE acquisition as well as design strategies to reduce local transmission on return.

Infectious Disease Risk Across the Growing Human-Non Human Primate Interface: A Review of the Evidence

Most of the human pandemics reported to date can be classified as zoonoses. Among these, there is a long history of infectious diseases that have spread from non-human primates (NHP) to humans. For millennia, indigenous groups that depend on wildlife for their survival were exposed to the risk of NHP pathogens' transmission through animal hunting and wild meat consumption. Usually, exposure is of no consequence or is limited to mild infections. In rare situations, it can be more severe or even become a real public health concern. Since the emergence of acquired immune deficiency syndrome (AIDS), nobody can ignore that an emerging infectious diseases (EID) might spread from NHP into the human population. In large parts of Central Africa and Asia, wildlife remains the primary source of meat and income for millions of people living in rural areas. However, in the past few decades the risk of exposure to an NHP pathogen has taken on a new dimension. Unprecedented breaking down of natural barriers between NHP and humans has increased exposure to health risks for a much larger population, including people living in urban areas. There are several reasons for this: (i) due to road development and massive destruction of ecosystems for agricultural needs, wildlife and humans come into contact more frequently; (ii) due to ecological awareness, many long distance travelers are in search of wildlife discovery, with a particular fascination for African great apes; (iii) due to the attraction for ancient temples and mystical practices, others travelers visit Asian places colonized by NHP. In each case, there is a risk of pathogen transmission through a bite or another route of infection. Beside the individual risk of contracting a pathogen, there is also the possibility of starting a new pandemic. This article reviews the known cases of NHP pathogens' transmission to humans whether they are hunters, travelers, ecotourists, veterinarians, or scientists working on NHP. Although pathogen transmission is supposed to be a rare outcome, Rabies virus, Herpes B virus, Monkeypox virus, Ebola virus, or Yellow fever virus infections are of greater concern and require quick countermeasures from public health professionals.

Carriage of Blastocystis spp. in travellers - A prospective longitudinal study

INTRODUCTION

A lack of prospective and longitudinal data on pre- and post-travel carriage of Blastocystis spp. complicates interpretation of a positive test post-travel. Therefore we studied dynamics of Blastocystis carriage in a cohort of Dutch travellers.

METHODS

From the prospective, multicentre COMBAT study among 2001 Dutch travellers, a subset of 491 travellers was selected based on travel destination to 7 subregions (70 or 71 travellers each). Faecal samples taken directly before and after travel were screened for Blastocystis with qPCR, followed, when positive, by sequence analysis to determine subtypes.

RESULTS

After exclusion of 12 samples with missing samples or inhibited qPCR-reactions, stool samples of 479 travellers were analysed. Before travel, 174 of them (36.3%) carried Blastocystis and in most of these, the same subtype was persistently carried. However, in 48/174 of those travellers (27.6%; CI95 20.8-36.6%) no Blastocystis or a different subtype was detected in the post-travel sample, indicating loss of Blastocystis during travel. Only 26 (5.4%; CI95 3.7%-8.0%) of all travellers acquired Blastocystis, including two individuals that were already positive for Blastocystis before travel but acquired a different subtype during travel.

DISCUSSION

This study shows that Blastocystis carriage in travellers is highly dynamic. The observed acquisition and loss of Blastocystis could either be travel-related or reflect the natural course of Blastocystis carriage. We demonstrate that the majority of Blastocystis detected in post-travel samples were already carried before travel.

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.