Prevalence, genetic characteristics, and antimicrobial resistance of Clostridioides difficile isolates from horses in Korea

OBJECTIVES

Clostridioides difficile is an etiological agent of enteric diseases in humans and animals. Animals are considered a potential reservoir due to the genetic and antimicrobial resistance similarities between human and animal C. difficile isolates. In this study, we evaluated the genetic characteristics and antimicrobial resistance profiles of C. difficile isolated from 942 fecal samples collected from horses in South Korea during 2019-2020.

METHODS

The C. difficile isolates were tested for toxin genes including tcdA (A), tcdB (B), and cdtAB (CDT) and deletions of the tcdC gene by PCR. In addition, ribotyping, multilocus sequence typing, and antimicrobial susceptibility tests were performed.

RESULTS

Twenty-three (2.4%) C. difficile isolates were associated with diarrhea in foals under 1 year old during the spring-summer period. Of these, 82.6% were toxigenic strains, determined to be A⁺B⁺CDT⁺ (52.1%) or A⁺B⁺CDT^‒ (30.4%). All isolates were susceptible to metronidazole and vancomycin, and resistant to cefotaxime and gentamicin, and 76.2% were multidrug resistant (MDR). RT078/ST11/Clade 5 was the most common genotype (47.8%), which was also found in animals and humans worldwide. All RT078/ST11/Clade 5 strains were toxigenic and had deletions of the tcdC gene. About half of these strains were resistant to moxifloxacin, and 63.6% were MDR.

CONCLUSIONS

C. difficile isolates in this study consisted mostly of toxigenic and MDR strains, and their genetic properties were highly similar to human C. difficile isolates. These results suggest high possibilities of zoonotic transmission and can provide knowledge for establishing strategies for the treatment and prevention of C. difficile infection.

Experimental infectious challenge in pigs leads to elevated fecal calprotectin levels following colitis, but not enteritis

BACKGROUND

Fecal calprotectin is largely applied as a non-invasive intestinal inflammation biomarker in human medicine. Previous studies in pigs investigated the levels of fecal calprotectin in healthy animals only. Thus, there is a knowledge gap regarding its application during infectious diarrhea. This study investigated the usefulness of fecal calprotectin as a biomarker of intestinal inflammation in Brachyspira hyodysenteriae and Salmonella Typhimurium infected pigs.

RESULTS

Fecal samples from pigs with colitis (n = 18) were collected from animals experimentally inoculated with B. hyodysenteriae (n = 8) or from sham-inoculated controls (n = 3). Fecal samples from pigs with enteritis (n = 14) were collected from animals inoculated with Salmonella enterica serovar Typhimurium (n = 8) or from sham-inoculated controls (n = 4). For both groups, fecal samples were scored as: 0 = normal; 1 = soft, wet cement; 2 = watery feces; 3 = mucoid diarrhea; and 4 = bloody diarrhea. Fecal calprotectin levels were assayed using a sandwich ELISA, a turbidimetric immunoassay and a point-of-care dipstick test. Fecal calprotectin levels were greater in colitis samples scoring 4 versus ≤ 4 using ELISA, and in feces scoring 3 and 4 versus ≤ 1 using immunoturbidimetry (P < 0.05). No differences were found in calprotectin concentration among fecal scores for enteritis samples, regardless of the assay used. All samples were found below detection limits using the dipstick method.

CONCLUSIONS

Fecal calprotectin levels are increased following the development of colitis, but do not significantly change due to enteritis. While practical, the use of commercially available human kits present sensitivity limitations. Further studies are needed to validate the field application of calprotectin as a marker of intestinal inflammation.

Prevalence of rotavirus among older children and adults with diarrhea: A systematic review and meta-analysis

BACKGROUND

Older children and adults are susceptible to rotavirus, but the extent to which rotavirus affects this population is not fully understood, hindering accuracy of global rotavirus estimations.

OBJECTIVE

To determine what proportion of diarrhea cases are due to rotavirus among persons ≥ 5 years old and to estimate this proportion by age strata.

METHODS

We conducted a systematic review and meta-analysis using the PRISMA guidelines. We included studies that reported on conditional rotavirus prevalence (i.e., percent of diarrhea due to rotavirus) in persons ≥ 5 years old who were symptomatic with diarrhea/gastroenteritis and had laboratory confirmation for rotavirus infection. Studies on nosocomial infections and outbreak investigations were excluded. We collected age group-specific conditional rotavirus prevalence and other variables, such as study geography, study setting, and study type. We calculated pooled conditional rotavirus prevalence, corresponding 95% confidence intervals (95% CI), heterogeneity (I²) estimates, and prediction intervals (PI).

RESULTS

Sixty-six studies from 32 countries met the inclusion criteria. Conditional rotavirus prevalence ranged from 0% to 30% across the studies. The total pooled prevalence of rotavirus among persons ≥ 5 years old with diarrhea was 7.6% (95% CI: 6.2-9.2%, I² = 99.6%, PI: 0-24%). The pooled prevalence of rotavirus among older children and adolescents was 8.7% (95% CI: 6.2-11.7%, I² = 96%, PI:0-27%), among younger adults was 5.4% (95% CI: 1.4-11.8%, I² = 96%, PI:0-31%), and among older adults was 4.7% (95% CI: 2.8-7.0%, I² = 96%, PI:0-16%). Pooled conditional rotavirus prevalences did not differ by other variables.

CONCLUSION

In this systematic review and meta-analysis of rotavirus among persons ≥ 5 years old with diarrhea, we found relatively low pooled conditional rotavirus prevalence compared to what is typically reported for children < 5 years; however, results should be interpreted with caution as the wide prediction intervals suggest large heterogeneity.

ClinEpiDB: an open-access clinical epidemiology database resource encouraging online exploration of complex studies

The concept of open data has been gaining traction as a mechanism to increase data use, ensure that data are preserved over time, and accelerate discovery. While epidemiology data sets are increasingly deposited in databases and repositories, barriers to access still remain. ClinEpiDB was constructed as an open-access online resource for clinical and epidemiologic studies by leveraging the extensive web toolkit and infrastructure of the Eukaryotic Pathogen Database Resources (EuPathDB; a collection of databases covering 170+ eukaryotic pathogens, relevant related species, and select hosts) combined with a unified semantic web framework. Here we present an intuitive point-and-click website that allows users to visualize and subset data directly in the ClinEpiDB browser and immediately explore potential associations. Supporting study documentation aids contextualization, and data can be downloaded for advanced analyses. By facilitating access and interrogation of high-quality, large-scale data sets, ClinEpiDB aims to spur collaboration and discovery that improves global health.

ClinEpiDB: an open-access clinical epidemiology database resource encouraging online exploration of complex studies

The concept of open data has been gaining traction as a mechanism to increase data use, ensure that data are preserved over time, and accelerate discovery. While epidemiology data sets are increasingly deposited in databases and repositories, barriers to access still remain. ClinEpiDB was constructed as an open-access online resource for clinical and epidemiologic studies by leveraging the extensive web toolkit and infrastructure of the Eukaryotic Pathogen Database Resources (EuPathDB; a collection of databases covering 170+ eukaryotic pathogens, relevant related species, and select hosts) combined with a unified semantic web framework. Here we present an intuitive point-and-click website that allows users to visualize and subset data directly in the ClinEpiDB browser and immediately explore potential associations. Supporting study documentation aids contextualization, and data can be downloaded for advanced analyses. By facilitating access and interrogation of high-quality, large-scale data sets, ClinEpiDB aims to spur collaboration and discovery that improves global health.

Quantitative Microbial Risk Assessment and Infectious Disease Transmission Modeling of Waterborne Enteric Pathogens

PURPOSE OF REVIEW

Waterborne enteric pathogens remain a global health threat. Increasingly, quantitative microbial risk assessment (QMRA) and infectious disease transmission modeling (IDTM) are used to assess waterborne pathogen risks and evaluate mitigation. These modeling efforts, however, have largely been conducted independently for different purposes and in different settings. In this review, we examine the settings where each modeling strategy is employed.

RECENT FINDINGS

QMRA research has focused on food contamination and recreational water in high-income countries (HICs) and drinking water and wastewater in low- and middle-income countries (LMICs). IDTM research has focused on large outbreaks (predominately LMICs) and vaccine-preventable diseases (LMICs and HICs). Human ecology determines the niches that pathogens exploit, leading researchers to focus on different risk assessment research strategies in different settings. To enhance risk modeling, QMRA and IDTM approaches should be integrated to include dynamics of pathogens in the environment and pathogen transmission through populations.

Associations between soil-transmitted helminthiasis and viral, bacterial, and protozoal enteroinfections: a cross-sectional study in rural Laos

Background

Humans are susceptible to over 1400 pathogens. Co-infection by multiple pathogens is common, and can result in a range of neutral, facilitative, or antagonistic interactions within the host. Soil-transmitted helminths (STH) are powerful immunomodulators, but evidence of the effect of STH infection on the direction and magnitude of concurrent enteric microparasite infections is mixed.

Methods

We collected fecal samples from 891 randomly selected children and adults in rural Laos. Samples were analyzed for 5 STH species, 6 viruses, 9 bacteria, and 5 protozoa using a quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay. We utilized logistic regression, controlling for demographics and household water, sanitation, and hygiene access, to examine the effect of STH infection on concurrent viral, bacterial, and protozoal infection.

Results

We found that STH infection was associated with lower odds of concurrent viral infection [odds ratio (OR): 0.48, 95% confidence interval (CI): 0.28–0.83], but higher odds of concurrent bacterial infections (OR: 1.81, 95% CI: 1.06–3.07) and concurrent protozoal infections (OR: 1.50, 95% CI: 0.95–2.37). Trends were consistent across STH species.

Conclusions

The impact of STH on odds of concurrent microparasite co-infection may differ by microparasite taxa, whereby STH infection was negatively associated with viral infections but positively associated with bacterial and protozoal infections. Results suggest that efforts to reduce STH through preventive chemotherapy could have a spillover effect on microparasite infections, though the extent of this impact requires additional study. The associations between STH and concurrent microparasite infection may reflect a reverse effect due to the cross-sectional study design. Additional research is needed to elucidate the exact mechanism of the immunomodulatory effects of STH on concurrent enteric microparasite infection.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3471-2) contains supplementary material, which is available to authorized users.

Porcine epidemic diarrhea (PED) infection, diagnosis and vaccination: A mini review

Porcine epidemic diarrhea virus (PEDV) is a main etiology causing severe enteric disease in piglets with clinical signs of anorexia, vomiting, diarrhea and dehydration resulting in loss of condition and death within a few days. Historically, PED is one of major causes of loss in swine and remains prevalent in some parts of the world. Even with increase in the available tests for PED diagnosis, which include histological diagnosis; virological diagnosis and serological diagnosis, there is no vaccine or specific treatment for this disease yet. In this mini review, the overview and current situation of PED is described with updated techniques, in an effort to comprehensively discuss and understand the disease characteristics.

Prevalence of histopathological intestinal lesions and enteric pathogens in Dutch commercial broilers with time

Intestinal disease has a major impact on the broiler industry due to economic and welfare reasons. Intestinal disease might occur due to a large number of reasons varying from well-defined pathogens to non-specific enteritis and complex syndromes. However, knowledge about the nature of intestinal disease and presence of enteric viruses in the Dutch broiler industry is largely absent. Therefore, a large-scale field study, in which 98 broiler flocks from 86 farms were sampled weekly, was started to assess the prevalence of histopathological lesions in the jejunum, a number of enterotropic viruses by real-time quantitative reverse transcriptase PCR (RT-qPCR) and coccidia by lesion scoring. Histopathological lesions indicative of intestinal disease were found in all flocks examined. The pathogens investigated were chicken astrovirus (99% of flocks positive), avian nephritis virus 3 (100%), rotavirus A (95%), rotavirus D (52%), reovirus (100%), Eimeria acervulina (94%), E. maxima (49%) and E. tenella (40%). The enteric viruses were more prevalent in the first weeks of the growing period, while coccidiosis was more frequently found at 4 and 5 weeks of age. The abundant presence of the enteric viruses and enteric disorders stresses the need to elucidate the role of these viruses in intestinal disease. Furthermore, the high prevalence of coccidiosis despite the use of anticoccidials shows that the current coccidial management programmes might be insufficient in controlling this disease.

Effect of soy on faecal dry matter content and excretion of Brachyspira hyodysenteriae in pigs

The aim of this study was to investigate the effect of a soy diet on the excretion of Brachyspira hyodysenteriae in five farms with subclinically infected pigs. The effects on general health, faecal consistency and dry matter were analysed. In total, 200 pigs of different ages (group 1 <100 days of age (n=120) and group 2 ≥100 days (n=80)) were randomly assigned to the control (C) and the treatment (T) groups. Group C received the farm's standard diet. In group T half of the daily feed ration was replaced by pure soy on two consecutive days. Faecal scores were used to determine faecal consistency and a microwave method to assess faecal dry matter content (FDMC). In age group 1, soy feeding resulted in a statistically significant decrease of the FDMC of 2.5 per cent compared with group C and in age group 2 in a significant increase of 2.2 per cent compared with group C at day 2. Overall seven (T: 5, C: 2) out of 597 faecal samples tested positive for B hyodysenteriae by PCR.

In conclusion, a high soy diet applied over two days influenced the faecal consistency and the FDMC in growers, finishers and sows under field conditions. Further investigations with more sensitive diagnostic methods are needed to prove a potential influence of a high soy diet on the detection rate of B hyodysenteriae in subclinically infected herds.

Haloarchaeal gas vesicle nanoparticles displaying Salmonella SopB antigen reduce bacterial burden when administered with live attenuated bacteria

Innovative vaccines against typhoid and other Salmonella diseases that are safe, effective, and inexpensive are urgently needed. In order to address this need, buoyant, self-adjuvating gas vesicle nanoparticles (GVNPs) from the halophilic archaeon Halobacterium sp. NRC-1 were bioengineered to display the highly conserved Salmonella enterica antigen SopB, a secreted inosine phosphate effector protein injected by pathogenic bacteria during infection into the host cell. Two highly conserved sopB gene segments near the 3'-coding region, named sopB4 and B5, were each fused to the gvpC gene, and resulting GVNPs were purified by centrifugally accelerated flotation. Display of SopB4 and B5 antigenic epitopes on GVNPs was established by Western blotting analysis using antisera raised against short synthetic peptides of SopB. Immunostimulatory activities of the SopB4 and B5 nanoparticles were tested by intraperitoneal administration of recombinant GVNPs to BALB/c mice which had been immunized with S. enterica serovar Typhimurium 14028 ΔpmrG-HM-D (DV-STM-07), a live attenuated vaccine strain. Proinflammatory cytokines IFN-γ, IL-2, and IL-9 were significantly induced in mice boosted with SopB5-GVNPs, consistent with a robust Th1 response. After challenge with virulent S. enterica serovar Typhimurium 14028, bacterial burden was found to be diminished in spleen of mice boosted with SopB4-GVNPs and absent or significantly diminished in liver, mesenteric lymph node, and spleen of mice boosted with SopB5-GVNPs, indicating that the C-terminal portions of SopB displayed on GVNPs elicit a protective response to Salmonella infection in mice. SopB antigen-GVNPs were found to be stable at elevated temperatures for extended periods without refrigeration in Halobacterium cells. The results all together show that bioengineered GVNPs are likely to represent a valuable platform for the development of improved vaccines against Salmonella diseases.