Case-control study of diarrheal disease etiology in individuals over 5 years in southwest China

Prevalence and Associated Risk Factors of Intestinal Parasites among Diarrheic Under-Five Children Attending Bahir Dar and Han Health Centers, Northwest Ethiopia: A Cross-Sectional Study

Background. Intestinal parasitic infection is one of the major public health problems in developing countries including Ethiopia. The problem is highly pronounced in children under five years of age who are not able to adhere to prevention and control precautions. Objective. To assess the prevalence of intestinal parasitic infections (IPIs) and associated factors among diarrheic children under five years of age attending Bahir Dar and Han Health Centers, Bahir Dar, Northwest Ethiopia. Methods. An institution-based cross-sectional study was conducted among diarrheic children less than five years of age at Bahir Dar and Han Health Centers, Northwest Ethiopia, 2020. A total of 221 diarrheic children less than five years of age were recruited using the convenience sampling technique. Data were collected using a pretested structured Amharic version questionnaire after obtaining informed consent from children’s parents or guardians. Approximately 1 mL of fresh fecal specimen was collected and subjected to direct saline wet mount microscopy. All data were entered into Epi Info version 7 and transferred to SPSS statistical software version 20 for analysis. Logistic regression was employed to assess risk factors associated with increased prevalence of intestinal parasitic infection in diarrheic children under five years of age, and a $P$ value < 0.05 was taken as statistically significant. Results. The overall prevalence of intestinal parasites was 19% ( $95\%\text{CI}=14–24.6$ ). The most prevalent intestinal parasites were Entamoeba histolytica/Entamoeba dispar (24 (10.86%)), Giardia lamblia (12 (5.43%)), and Ascaris lumbricoides (2 (0.9%)). Children’s mother/guardian washed their hands sometimes after the toilet ( $\text{AOR}=2.98$ , 95% CI: 1.09-8.18), children who always eat unwashed fruits and vegetables ( $\text{AOR}=4.63$ , 95% CI: 1.09–19.75), and children’s mother/guardian who had no knowledge about the mode of transmission ( $\text{AOR}=4.03$ , 95% CI: 1.04–15.64) were risk factors significantly associated with increased intestinal parasitic infections. Conclusion. The prevalence of intestinal parasitic infections was found low compared to the population prevalence reported by WHO. However, strengthening health education about food and personal hygiene of both children and their mothers/guardians is crucial to limit the transmission of IPIs.

The Coexistence of Blastocystis spp. in Humans, Animals and Environmental Sources from 2010-2021 in Asia

Simple Summary

Blastocystis spp. are unicellular parasites that infect the gastrointestinal tract of humans and animals. Their occurrence in the environment had been detected in water sources, thus causing contamination. The presence of the parasites in humans, animals and environmental sources in Asia were reviewed according to countries in Asia, different categories of human and animal populations, and environmental sources including water samples, food and ambient air. The coexistence of the parasites poses a public health concern as the parasites are commonly found in most studies. Hence, there is a growing interest in the study of Blastocystis spp. Due to the isolation of Blastocystis spp. from living and non-living sources, a collaborative, multisectoral and transdisciplinary approach known as One Health is proposed for future study of Blastocystis spp. in order to achieve optimal health outcomes through the recognition of interconnection between people, animals and their shared environment.

Abstract

Blastocystis spp. are controversial unicellular protists that inhabit the gastrointestinal tract of humans and a wide range of animals worldwide. This review provides an overview of the prevalence and distribution of Blastocystis spp. and their subtypes throughout Asia. Research articles reporting on the presence of Blastocystis spp. in locations within Asia, between 1 January 2010, and 10 May 2021, were obtained from Scopus, PubMed, and Google Scholar. In 427 articles, the prevalence of Blastocystis spp. in 31 countries within the last decade was revealed. Isolates were found in humans, various mammals, birds, reptiles, insects, water sources, vegetables, and ambient air. Prevalence of Blastocystis spp. varied widely across host categories. Subtypes identified throughout Asia were STs 1–14, and ST18–22 (novel subtypes). ST1, ST2, ST3, ST4 were the most frequently isolated in humans; ST5 in pigs; ST10 and ST14 in goats, sheep, and cattle; and ST6 and ST7 in chickens. ST1 and ST3 were most common in water samples. ST1, ST2, ST3, ST4, ST5 and ST6 were shared by humans, animals, and water sources. There is a growing interest in the study of Blastocystis spp. and their subtypes in Asia. Due to the isolation of Blastocystis spp. from biotic and abiotic sources in Asia, the application of the One Health (OH) approach to the study of Blastocystis spp. is proposed for improved perception of this organism.

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.

Symptomatic and Asymptomatic Protist Infections in Hospital Inpatients in Southwestern China

Cryptosporidium spp., Entamoeba histolytica, Giardia duodenalis, and Blastocystis sp. infections have been frequently reported as etiological agents for gastroenteritis, but also as common gut inhabitants in apparently healthy individuals. Between July 2016 and March 2017, stool samples (n = 507) were collected from randomly selected individuals (male/female ratio: 1.1, age range: 38–63 years) from two sentinel hospitals in Tengchong City Yunnan Province, China. Molecular (PCR and Sanger sequencing) methods were used to detect and genotype the investigated protist species. Carriage/infection rates were: Blastocystis sp. 9.5% (95% CI: 7.1–12.4%), G. duodenalis 2.2% (95% CI: 1.1–3.8%); and E. histolytica 2.0% (95% CI: 0.9–3.6%). Cryptosporidium spp. was not detected at all. Overall, 12.4% (95% CI: 9.7–15.6) of the participants harbored at least one enteric protist species. The most common coinfection was E. histolytica and Blastocystis sp. (1.0%; 95% CI: 0.3–2.2). Sequence analyses revealed that 90.9% (10/11) of the genotyped G. duodenalis isolates corresponded to the sub-assemblage AI. The remaining sequence (9.1%, 1/11) was identified as sub-assemblage BIV. Five different Blastocystis subtypes, including ST3 (43.7%, 21/48), ST1 (27.1%, 13/48), ST7 (18.8%, 9/48), ST4 (8.3%, 4/48), and ST2 (2.1%, 1/48) were identified. Statistical analyses confirmed that (i) the co-occurrence of protist infections was purely random, (ii) no associations were observed among the four protist species found, and (iii) neither their presence, individually or jointly, nor the patient’s age was predictors for developing clinical symptoms associated with these infections. Overall, these protist mono- or coinfections are asymptomatic and do not follow any pattern.

Global prevalence and genotype distribution of norovirus infection in children with gastroenteritis: A meta-analysis on 6 years of research from 2015 to 2020

In the post rotavirus vaccine era, norovirus (NoV) plays an increasingly important role in epidemic and sporadic gastroenteritis among children. This study was designed to provide an updated meta-analytic review of the prevalence of NoV among paediatric patients with gastroenteritis and to clarify the relationship between NoV infection and gastroenteritis. Systematic searches of the literature for potentially relevant studies were carried out from 1 January 2015 to 29 May 2020. The inverse variance method was chosen for weighting of the studies, and the random-effects model was used to analyse data. To determine the association between NoV infection and gastroenteritis in children, pooled odds ratio (OR) and its 95% confidence interval (CI) were computed for case-control studies. The pooled prevalence of NoV infection among 12,0531 children with gastroenteritis from 45 countries across the world was 17.7% (95% CI: 16.3%-19.2%). There were 28 studies with a case-control design, and the pooled prevalence of NoV infection among 11,954 control subjects was 6.7% (95% CI: 5.1%-8.8%). The pooled OR of the association of NoV infection and gastroenteritis was 2.7 (95% CI: 2.2-3.4). The most common NoV genotypes were GII.4 (59.3%) and GII.3 (14.9%). The highest frequency of NoV was found in the age group below 1 year. Our findings indicated a substantial burden of gastroenteritis caused by NoV globally, with GII.4 and GII.3 the major genotypes responsible for the majority of NoV-associated gastroenteritis cases among children. Younger age and male sex can be considered risk factors for NoV-associated gastroenteritis among children.

Prevalence and genotype distribution of group A rotavirus circulating in Shanxi Province, China during 2015-2019

BACKGROUND

Group A rotavirus (RVA), despite being a leading cause of gastroenteritis in infants and young children, is less studied in Shanxi Province, China. The current study was conducted to determine the prevalence and genetic characterization of RVA in hospitalized children younger than 10 years of age with the diagnosis of acute gastroenteritis in Shanxi Province, China.

METHODS

A hospital-based active surveillance of rotavirus gastroenteritis was conducted at Children's Hospital of Shanxi from Jan 1, 2015, through Dec 31, 2019. Rotavirus was detected in stool samples by real-time quantitative reverse transcription PCR (qRT-PCR). G- and P-genotypes were determined by reverse transcription PCR (RT-PCR) and nucleotide sequencing.

RESULTS

A total of 961 children younger than 10 years of age was enrolled over the study period, of whom 183 (19.0%) were positive for RVA. The highest RVA-infection frequency (23.7%) was found among children aged 12-23 months, and the seasonal peak was in December. G9P[8] was most prevalent (76.0%), followed by G3P[8] (7.1%), G2P[4] (3.3%), G1P[8] (0.5%) and G9P[4] (0.5%).

CONCLUSIONS

These results report for the first time that RVA was one of the main causes of severe infectious gastroenteritis in children, and a high proportion of G9P[8] strains circulating in most areas of Shanxi Province. While the protective efficacy of the rotavirus vaccines has been demonstrated against G9P[8] strains, our results highlight that the dominant strains have not been effectively controlled in China.

Epidemiology of Blastocystis infection from 1990 to 2019 in China

Background

Blastocystis is ubiquitous presence in animals and humans worldwide and has a high level genetic diversity. The aim of this study was to conduct a summary of Blastocystis prevalence, subtypes (STs) in humans and animals in China and depict their distribution.

Methods

We searched for the articles related to epidemiology of Blastocystis in humans and animals throughout China which published from January 1, 1990, to July 31, 2019 in the following databases: PubMed, China National Knowledge Infrastructure (CNKI) and Wanfang database. The keywords were Blastocystis and one of the following ones: STs, subtypes, distribution, epidemiology, prevalence, infection, molecular, geographic, intestinal parasites, genetic diversity and characterization.

Results

In recent years, various molecular epidemiological studies have been carried out in some provinces/regions of China to identify subtypes of Blastocystis. Infants and young children, school students, hospitalized diarrhea patients, HIV/AIDS patients, tuberculosis patients, and cancer patients as respondents had been included. ST1–ST7 and ST12 were the main subtypes in Chinese population. Moreover, surveys of Blastocystis infection in animal were also conducted in some provinces of China. A variety of animals were investigated including pigs, cattle, sheep, yak, giant panda, and crested ibis (Nipponia nippon) with the main subtypes of ST1–ST8, ST10, ST12–ST14.

Conclusions

In recent years, some provinces/regions in China have conducted various molecular epidemiological studies to identify the Blastocystis subtypes. It is important to focus on new subtypes and mixed subtypes of infection, while increasing data on ribosomal alleles. We encourage the scientific community to start research on humans and surrounding animals (including domestic and wild animals) to better understand the possibility of Blastocystis transmission between humans and animals. We call for action among researchers studying intestinal parasitic diseases (Blastocystis), start drawing the subtype of Blastocystis and increase the subtype related to its clinical symptoms.

Prevalence of Enteropathogens and Virulence Traits in Brazilian Children With and Without Diarrhea

The use of molecular diagnostics for pathogen detection in epidemiological studies have allowed us to get a wider view of the pathogens associated with diarrhea, but the presence of enteropathogens in asymptomatic individuals has raised several challenges in understanding the etiology of diarrhea, and the use of these platforms in clinical diagnosis as well. To characterize the presence of the most relevant bacterial enteropathogens in diarrheal episodes, we evaluated here the prevalence of diarrheagenic E. coli pathotypes, Salmonella spp., and Yersinia enterocolitica in stool samples of children with and without diarrhea using real-time quantitative PCR (qPCR). We found that the presence of genetic markers associated with bacterial pathogens was significantly higher in stool samples from the diarrhea group compared to the control (P < 0.001). Bacterial loads in samples positive for eae and aggR markers were also determined. Compared to samples from asymptomatic children, a significantly higher number of copies of the eae gene were found in diarrhea samples. Also, the presence of genetic markers associated with STEC strains with clinical significance was evaluated in eae-positive samples by high-throughput real-time PCR. The data presented herein demonstrated that asymptomatic children of an urban area in Brazil might be enteropathogen reservoirs, especially for STEC.

Molecular Epidemiology and Risk Factors of Blastocystis sp. Infections Among General Populations in Yunnan Province, Southwestern China

Background

Blastocystis is a common enteric parasite of controversial pathogenic roles in human diseases. Although the prevalence of Blastocystis infections has been investigated in a diverse range of populations, there is little knowledge on the molecular epidemiology and risk factors of Blastocystis infections among general populations in southeastern China.

Materials and Methods

A total of 507 individuals were randomly selected in Yunnan province, China from July 2016 to March 2017. Stool specimens were sampled for detection of Blastocystis sp. using PCR assay, and the risk factors of Blastocystis infections were identified. Blastocystis isolates were subtyped, and the associations of Blastocystis infections and subtypes with clinical manifestations were examined.

Results

The overall detection rate of Blastocystis sp. was 9.47% (95% CI: 7.13–12.44%). Toilet type (OR = 3.248, 95% CI: 1.245–8.473), anemia (OR = 2.601, 95% CI: 1.245–8.473) and type of daily drinking water (OR = 3.11, 95% CI: 1.557–6.213) were identified as risk factors of Blastocystis infections; however, Blastocystis infections showed no associations with clinical symptoms. Four subtypes (ST1 to ST4) were characterized in Blastocystis isolates, in which ST3 was predominant (4.73%, 95% CI: 3.2–6.94%), followed by ST1 (3.16%, 95% CI: 1.95–5.07%), ST4 (1.38%, 95% CI: 0.07–2.82%) and ST2 (0.2%, 95% CI: 0–1.11%). In addition, ST1 subtype infection was found to correlate with anemia (OR = 4.66, 95% CI: 1.631–14.314).

Conclusions

There is a high prevalence of Blastocystis infections among general populations in Yunnan province, southwestern China, and toilet type, anemia and type of daily drinking water are risk factors of Blastocystis infections. ST3 is the dominant subtype of Blastocystis sp. characterized, and ST1 correlates with anemia. Improving hygiene conditions, developing healthy lifestyles and intensifying health education programs are strongly recommended to reduce the prevalence and transmission potential of Blastocystis infections.

Etiology of acute gastroenteritis among children less than 5 years of age in Bucaramanga, Colombia: A case-control study

Background

Acute gastroenteritis (AGE) is a major cause of morbidity and mortality in children aged less than 5 years in low- and middle-income countries where limited access to potable water, poor sanitation, deficient hygiene, and food product contamination are prevalent. Research on the changing etiology of AGE and associated risk factors in Latin America, including Colombia, is essential to understand the epidemiology of these infections. The primary objectives of this study were to describe etiology of moderate to severe AGE in children less than 5 years of age from Bucaramanga, Colombia, a middle-income country in Latin American, and to identify the presence of emerging E. coli pathotypes.

Methodology/Principal findings

This was a prospective, matched for age, case-control study to assess the etiology of moderate to severe AGE in children less than 5 years of age in Bucaramanga, Colombia, South America. We tested for 24 pathogens using locally available diagnostic testing, including stool culture, polymerase chain reaction, microscopy and enzyme-linked immunoassay. Adjusted attributable fractions were calculated to assess the association between AGE and each pathogen in this study population. The study included 861 participants, 431 cases and 430 controls. Enteric pathogens were detected in 71% of cases and in 54% of controls (p = <0.001). Co-infection was identified in 28% of cases and in 14% of controls (p = <0.001). The adjusted attributable fraction showed that Norovirus GII explained 14% (95% CI: 10–18%) of AGE, followed by rotavirus 9.3% (6.4–12%), adenovirus 3% (1–4%), astrovirus 2.9% (0.6–5%), enterotoxigenic Escherichia coli (ETEC) 2.4% (0.4–4%), Cryptosporidium sp. 2% (0.5–4%), Campylobacter sp. 2% (0.2–4%), and Salmonella sp.1.9% (0.3 to 3.5%). Except for Cryptosporidium, all parasite infections were not associated with AGE. Three emergent diarrheagenic E. coli pathotypes were identified in cases (0.7%), including an enteroaggregative/enterotoxigenic E.coli (EAEC/ETEC), an enteroaggregative/enteropathogenic E.coli (EAEC/EPEC), and an emergent enteroinvasive E. coli with a rare O96:H19. No deaths were reported among cases or controls.

Conclusions/Significance

Norovirus and rotavirus explained the major proportion of moderate to severe AGE in this study. Higher proportion of infection in cases, in the form of single infections or co-infections, showed association with AGE. Three novel E. coli pathotypes were identified among cases in this geographic region.

Acute gastroenteritis (AGE) is a leading cause of mortality in children under 5 years of age in low- and middle-income countries (LMIC). The highest burden of AGE disease is concentrated in tropical areas where populations lack access to clean water, adequate sanitation and hygiene, making this condition a neglected disease. Limited information on etiology, associated malnutrition, and mortality among underserved communities makes difficult the development of strategies for AGE prevention and treatment. This case-control study among children less than 5 years of age in Bucaramanga, Colombia, revealed that viral followed by bacterial organisms explained the larger proportion of AGE, being norovirus the most common organism. The higher rate of infections and co-infections among cases compared to controls was associated with AGE. This study also reports the identification of three new E. coli pathotypes among cases designated as biofilm-forming enteroinvasive E. coli (BF-EIEC), enteroaggregative/enteropathogenic E. coli, and enteroaggregative/enterotoxigenic E. coli (EAEC/ETEC).

Stool cultures show a lack of impact in the management of acute gastroenteritis for hospitalized patients in the Bronx, New York

Background

Acute gastroenteritis (AGE) is diagnosed with a presentation of > 1 episode of vomiting and > 3 episodes of diarrhea in a 24-h period. Treatment is supportive, however, in severe cases antibacterial treatment may be indicated. Stool cultures can detect the responsible pathogenic bacteria and can guide antibiotic treatment, however, the indication for and efficacy of stool cultures is debatable. This study aimed to address the clinical utility of stool cultures in patients diagnosed with AGE.

Methods

A retrospective, multicenter study was performed in patients admitted for AGE from 2012 to 2014. Patient charts were obtained through hospital software using ICD-9 codes for AGE. Inclusion criteria was a documented diagnosis of AGE, age of 18 years or older, symptoms of both upper GI symptoms of abdominal pain and/or nausea and lower GI symptoms of diarrhea. Patients were classified into two main groups, those in whom (1) stool culture was obtained and (2) those in whom stool culture was not performed. Clinical features and outcomes were compared between groups. The diagnostic yield of stool cultures was assessed. All analysis were conducted using the Statistical Package for Social Science (SPSS).

Results

Of 2479 patient charts reviewed, 342 met the above criteria for AGE. 119 patients (34.8%) had stool cultures collected and 223 (65.2%) did not. Demographics, clinical features and serologic lab values are shown in Table 1. Of the 119 stool cultures performed, only 4% (n = 5) yielded growth of pathogenic bacteria (2 Pseudomonas spp, 2 Campylobacter spp, 1 Salmonella spp). The group who underwent stool culture had a higher percentage of patients with fevers (26% vs 13%,p < 0.003) and longer hospital length of stay (3.15 vs 2.28 days, p < 0.001) compared to the group that did not undergo stool cultures.

Conclusion

Stool cultures are commonly ordered when AGE is suspected. In our cohort, stool culture had a very low yield of detecting an underlying pathogen. Although patients who had stool cultures obtained were more likely to be febrile and to have a longer length of hospital stay than were those who did not have stool cultures, for the vast majority of patients, stool culture played little to no role in patient management. Further studies are needed to which patients benefit most from undergoing stool culture.

Blastocystis sp. Subtype Diversity in Wild Carnivore Species from Spain

The occurrence and molecular diversity of the stramenopile eukaryote Blastocystis sp. was investigated by PCR and sequencing (Sanger and NGS) methods in 380 faecal specimens of free-living carnivores in Spain. Blastocystis sp. was confirmed in 1.6% (6/380) of the specimens analysed. Two samples from a common genet and a fox were successfully subtyped as ST7 by Sanger. Using NGS, ST14 was found in a fox and a European polecat, ST7 in a fox, and two additional foxes presented mixed infections of ST1/ST2/ST4 and ST1/ST2/ST7, respectively. Wild carnivore species could act as carriers of zoonotic Blastocystis subtypes.

Risk factors for Blastocystis infection in HIV/AIDS patients with highly active antiretroviral therapy in Southwest China

Background

Blastocystis is a widespread zoonotic protozoan of mammalian species, especially in HIV/AIDS individuals. The aim of this study was to analyze the prevalence and risk factors related with Blastocystis infection among HIV/AIDS patients in Southwest China.

Methods

The cross-sectional study was performed in 311 HIV/AIDS cases in Tengchong City, Yunnan Province from July 2016 to March 2017. For each subject, stool specimen was collected to detect the Blastocystis, and the blood sample was used to detect HIV virus load and CD4⁺ T cell count, in addition, structured questionnaire was used to collect the basic information and risk factors.

Findings

The result showed that the detection rate of Blastocystis was 3.86% (95% CI: 2.22–6.62) among HIV/AIDS patients. Both raising animal (OR = 12.93, 95% CI: 1.54–108.36) and drinking un-boiled water (OR = 8.17, 95% CI: 1.76–37.90) were risk factors for Blastocystis infection in HIV/AIDS individuals. In addition, the interaction of CD4⁺ T cell count and HIV virus load was also contribution to Blastocystis infection (P = 0.007).

Conclusions

A high prevalence of Blastocystis infection was found in HIV/AIDS patients in Tengchong. Poor hygienic habits, the interaction of HIV virus load and CD4⁺ T cell count were identified as main risk factors for infection. These results will help us to develop efficient control strategies to intervene with and prevent the occurrence of Blastocystis among HIV-infected individuals.

Exploring interactions between Blastocystis sp., Strongyloides spp. and the gut microbiomes of wild chimpanzees in Senegal

BACKGROUND

Gut parasites exert an important influence on the gut microbiome, with many studies focusing on the human gut microbiome. It has, however, undergone severe richness depletion. Hygienic lifestyle, antimicrobial treatments and altered gut homeostasis (e.g., chronic inflammation) reduce gut microbiome richness and also parasite prevalence; which may confound results. Studying species closely related to humans could help overcome this problem by providing insights into the ancestral relationship between humans, their gut microbiome and their gut parasites. Chimpanzees are a particularly promising model as they have similar gut microbiomes to humans and many parasites infect both species.

AIMS

We study the interaction between gut microbiome and enteric parasites in chimpanzees. Investigating what novel insights a closely related species can reveal when compared to studies on humans.

METHODS

Using eighty-seven faecal samples from wild western chimpanzees (Pan troglodytes verus) in Senegal, we combine 16S rRNA gene amplicon sequencing for gut microbiome characterization with PCR detection of parasite taxa (Blastocystis sp., Strongyloides spp., Giardia duodenalis, Cryptosporidium spp., Plasmodium spp., Filariae and Trypanosomatidae). We test for differences in gut microbiota ecosystem traits and taxonomical composition between Blastocystis and Strongyloides bearing and non-bearing samples.

RESULTS

For Blastocystis, twelve differentially abundant taxa (e.g., Methanobrevibacter), including Prevotella and Ruminococcus-Methanobrevibacter enterotype markers, replicate findings in humans. However, several richness indices are lower in Blastocystis carriers, contradicting human studies. This indicates Blastocystis, unlike Strongyloides, is associated to a "poor health" gut microbiome, as does the fact that Faecalibacterium, a bacterium with gut protective traits, is absent in Blastocystis-positive samples. Strongyloides was associated to Alloprevotella and five other taxonomic groups. Each parasite had its unique impact on the gut microbiota indicating parasite-specific niches. Our results suggest that studying the gut microbiomes of wild chimpanzees could help disentangle biological from artefactual associations between gut microbiomes and parasites.

Virulence gene profiles and molecular genetic characteristics of diarrheagenic Escherichia coli from a hospital in western China

Background

Diarrheagenic Escherichia coli (DEC) is one of the most important etiological agents of diarrheal diseases. In this study we investigated the prevalence, virulence gene profiles, antimicrobial resistance, and molecular genetic characteristics of DEC at a hospital in western China.

Methods

A total of 110 Escherichia coli clinical isolates were collected from the First Affiliated Hospital of Chengdu Medical College from 2015 to 2016. Microbiological methods, PCR, antimicrobial susceptibility test, pulsed-field gel electrophoresis and multilocus sequence typing were used in this study.

Results

Molecular analysis of six DEC pathotype marker genes showed that 13 of the 110 E. coli isolates (11.82%) were DEC including nine (8.18%) diffusely adherent Escherichia coli (DAEC) and four (3.64%) enteroaggregative Escherichia coli (EAEC). The adherence genes fimC and fimH were present in all DAEC and EAEC isolates. All nine DAEC isolates harbored the virulence genes fyuA and irp2 and four (44.44%) also carried the hlyA and sat genes. The virulence genes fyuA, irp2, cnf1, hlyA, and sat were found in 100%, 100%, 75%, 50%, and 50% of EAEC isolates, respectively. In addition, all DEC isolates were multidrug resistant and had high frequencies of antimicrobial resistance. Molecular genetic characterization showed that the 13 DEC isolates were divided into 11 pulsed-field gel electrophoresis patterns and 10 sequence types.

Conclusions

To the best of our knowledge, this study provides the first report of DEC, including DAEC and EAEC, in western China. Our analyses identified the virulence genes present in E. coli from a hospital indicating their role in the isolated DEC strains’ pathogenesis. At the same time, the analyses revealed, the antimicrobial resistance pattern of the DEC isolates. Thus, DAEC and EAEC among the DEC strains should be considered a significant risk to humans in western China due to their evolved pathogenicity and antimicrobial resistance pattern.

Characteristics of microbial communities and intestinal pathogenic bacteria for migrated Larus ridibundus in southwest China

Larus ridibundus, a migratory wild bird, has become one of the most popular gull species in southwest China in recent years. There has been no information on the gut microbiota and intestinal pathogenic bacteria configuration in wild L. ridibundus, even though the public are in close contact with this bird. In this study, 16S rRNA amplicon‐sequencing methods were used to describe the microbial community structure and intestinal pathogenic bacteria were isolated to identify their characteristics. The taxonomic results revealed that Firmicutes (86%), Proteobacteria (10%), and Tenericutes (3%) were the three most abundant phyla in the gut of L. ridibundus. Enterococcaceae, Enterobacteriaceae, and Mycoplasmataceae were the most predominant families, respectively. The number of operational taxonomic units (OTUs), the richness estimates and diversity indices of microbiota, was statistically different (p < 0.05). However, beta diversity showed that no statistical significance (p > 0.05) between all the fecal samples. The most frequently isolated intestinal pathogenic bacteria from L. ridibundus were enteropathogenic Escherichia coli (32%) and Salmonella (21%). Pulsed‐field gel electrophoresis (PFGE) results of Salmonella species revealed a high degree of similarity between isolates, which was not observed for other species. None of the potentially pathogenic isolates were identical to human‐isolated counterparts suggesting that there was little cross‐infection between humans and gulls, despite close proximity. In brief, this study provided a baseline for future L. ridibundus microbiology analysis, and made an understanding of the intestinal bacterial community structure and diversity.

Antibiotic resistance and molecular characterization of diarrheagenic Escherichia coli and non-typhoidal Salmonella strains isolated from infections in Southwest China

BACKGROUND

Bacterial diarrhea is one of the most common causes for medical consultations, mortality and morbidity in the world. Diarrheagenic Escherichia coli (DEC) and non-typhoidal Salmonella (NTS) are major intestinal pathogens in developing countries, and the indiscriminate use of antibiotics has greatly contributed to resistant strains. Hence, the aim of the present study is to identify the antimicrobial resistance patterns and the molecular characteristics of DEC and NTS in southwest, China.

METHODS

1121 diarrheal patients and 319 non-diarrheal subjects across all age groups were recruited from four sentinel hospitals from June 2014 to July 2015 in Kunming City, Yunnan Province. Each stool specimen was collected to detect DEC and NTS with standard microbiological and molecular methods. Antimicrobial resistance testing was performed with the Kirby-Bauer disk diffusion method, and the standards for antimicrobial susceptibility testing complied with the Clinical and Laboratory Standards Institute (CLSI). Molecular characterization of strains was carried out using pulsed-field gel electrophoresis (PFGE). A structured questionnaire was used to record basic epidemiological data (e.g. sex, age, residence, season, etc.). Data were analyzed using Chi-square or Fisher's exact test.

RESULTS

DEC was detected in 127 (11.33%) diarrhea cases and 9 (2.82%) non-diarrheal cases (χ² = 20.69, P < 0.001, OR = 4.36, 95% CI: 2.19-8.65), and the prevalence of NTS isolated from diarrhea cases was higher than that of non-diarrheal cases across all age groups (n = 42, 3.75%, n = 1, 0.31%, χ² = 10.10, P = 0.002, OR = 12.38, 95% CI: 1.70-90.29). The rates of resistance to ten antibiotics of DEC and NTS showed significant differences (χ ²  = 386.77, P < 0.001; χ² = 191.16, P < 0.001). The rates of resistance to Amoxicillin and Clavulafiate (AMC), Cephalothin (CEP), Gentamicin (GEN) and Sulfamethoxazole-Trimethoprim (SXT) of DEC isolated from diarrhea cases were higher than those of NTS isolated from diarrhea patients (37.01% vs 14.29%, χ² = 7.57, P = 0.006; 29.92% vs 11.90%, χ² = 5.40, P = 0.02; 37.01% vs 11.90%, χ² = 5.80, P = 0.016; 62.20% vs 26.19%, χ² = 16.44, P < 0.001; respectively). Ciprofloxacin (CIP) was the most sensitive antibiotic for DEC and NTS strains isolated from diarrhea cases. Resistance rates of DEC isolates from cases and controls to more than three kinds antimicrobials (multidrug resistance, MDR) showed no significant differences (81.10% vs 88.89%, P = 0.33). Pulsotype patterns of DEC strains were highly diverse; however, the pulsotype pattern of NTS strains was closely related to the serotype. The pattern of S. enteritidis was highly similar, but the S. enterica Typhimurium strain was discrete.

CONCLUSIONS

Antibiotic resistance of Enterobacteriaceae is of great concern. The societal effects of antibiotic use justify strict monitoring to combat increases in antimicrobial resistance. Molecular epidemiology and systematic epidemiological investigation can provide accurate evidence for tracking the infection source.

A retrospective study of community-acquired Clostridium difficile infection in southwest China

To identify the prevalence and characteristics of community-acquired Clostridium difficile infection (CA-CDI) in southwest China, we conducted a cross-sectional study. 978 diarrhea patients were enrolled and stool specimens’ DNA was screened for virulence genes. Bacterial culture was performed and isolates were characterized by PCR ribotyping and multilocus sequence typing. Toxin genes tcdA and/or tcdB were found in 138/978 (14.11%) cases for fecal samples. A total of 55 C. difficile strains were isolated (5.62%). The positive rate of toxin genes and isolation results had no statistical significance between children and adults groups. However, some clinical features, such as fecal property, diarrhea times before hospital treatment shown difference between two groups. The watery stool was more likely found in children, while the blood stool for adults; most of children cases diarrhea ≤3 times before hospital treatment, and adults diarrhea >3 times. Independent risk factor associated with CA-CDI was patients with fever. ST35/RT046 (18.18%), ST54/RT012 (14.55%), ST3/RT001 (14.55%) and ST3/RT009 (12.73%) were the most distributed genotype profiles. ST35/RT046, ST3/RT001 and ST3/RT009 were the commonly found in children patients but ST54/RT012 for adults. The prevalence of CA-CDI in Yunnan province was relatively high, and isolates displayed heterogeneity between children and adults groups.

Investigating Potential Modes of Actions of Mimusops kummel Fruit Extract and Solvent Fractions for Their Antidiarrheal Activities in Mice

Background

Fruits of Mimusops kummel A. DC. (Sapotaceae) are traditionally used for the treatment of diarrhea. The present study aimed at investigating modes of actions of this fruits for antidiarrheal action to guide future drug development process.

Methods

Fractions of chloroform, n-butanol, and water were obtained from 80% methanol extract, which was prepared by maceration. Antidiarrheal activities and the modes of actions were investigated in mice.

Results

In castor oil induced diarrheal model, the extract delayed onset of diarrhea and reduced number and weight of feces at all tested doses significantly. In this model all fractions significantly delayed onset of diarrhea at all tested doses. Charcoal meal test showed that the extract and all the fractions produced a significant antimotility effect at all tested doses. Enteropooling test showed that the extract as well as n-butanol and aqueous fractions at all tested doses produced a significant decline in volume and weight of intestinal contents, whereas chloroform fraction had substantial effect only at high dose.

Conclusion

This study demonstrated that the extract and solvent fractions produced antidiarrheal activities due to dual inhibitory effect, intestinal motility, and fluid secretion, with the aqueous fraction being the most active among fractions in three models.

Prospective study on the overuse of blood test-guided antibiotics on patients with acute diarrhea in primary hospitals of China

BACKGROUND

Overuse with antibiotics in the treatment of infectious diseases has become a central focus of public health over the years. The aim of this study was to provide an up-to-date evaluation of the blood test-guided antibiotic use on patients with acute diarrhea in primary hospitals of China.

MATERIALS AND METHODS

A cross-sectional survey was conducted on 330 patients with acute diarrhea in Shanghai, People's Republic of China, from March 2013 to February 2016. These patients were treated with or without antibiotics based on the results of their blood tests, including examinations of C-reactive protein (CRP), white blood cells (WBC), and the percentage of neutrophils (Neu%). The infection types, which included bacterial, viral, and combination diarrhea, were determined by microbiological culture methods. Antibiotics used in non-bacterial diarrhea patients were considered misused and overused.

RESULTS

There were significant overall differences in the clinical characteristics and blood tests between patients with diarrhea with a bacterial infection and patients with other types of infections. The patients were divided into four grading groups (0-3) according to the number of the positive results from three blood testes (CRP, WBC, and Neu%). The misuse rates of antibiotics in each group (0-3) were 81.3%, 71.1%, 72.4%, and 64.9%, respectively.

CONCLUSION

In this prospective study, the current diagnostic criteria (CRP, WBC, and Neu%) based on blood tests are not reliable in diagnosing bacterial diarrhea or guiding antibiotics use. To limit antibiotic overuse, a rapid and accurate differentiation of bacterial diarrhea from other types of diarrhea is pivotal.