The relation between Blastocystis and the intestinal microbiota in Swedish travellers

Identification of a muropeptide precursor transporter from gut microbiota and its role in preventing intestinal inflammation

The gut microbiota is a considerable source of biologically active compounds that can promote intestinal homeostasis and improve immune responses. Here, we used large expression libraries of cloned metagenomic DNA to identify compounds able to sustain an anti-inflammatory reaction on host cells. Starting with a screen for NF-κB activation, we have identified overlapping clones harbouring a heterodimeric ATP-binding cassette (ABC)-transporter from a Firmicutes. Extensive purification of the clone's supernatant demonstrates that the ABC-transporter allows for the efficient extracellular accumulation of three muropeptide precursor, with anti-inflammatory properties. They induce IL-10 secretion from human monocyte-derived dendritic cells and proved effective in reducing AIEC LF82 epithelial damage and IL-8 secretion in human intestinal resections. In addition, treatment with supernatants containing the muropeptide precursor reduces body weight loss and improves histological parameters in Dextran Sulfate Sodium (DSS)-treated mice. Until now, the source of peptidoglycan fragments was shown to come from the natural turnover of the peptidoglycan layer by endogenous peptidoglycan hydrolases. This is a report showing an ABC-transporter as a natural source of secreted muropeptide precursor and as an indirect player in epithelial barrier strengthening. The mechanism described here might represent an important component of the host immune homeostasis.

Prevalence of Blastocystis and Dientamoeba fragilis in diarrheal patients in Corum, Türkiye

To investigate the prevalence of Blastocystis and Dientamoeba fragilis in diarrhea patients and healthy individuals in Corum, Türkiye, fecal samples from 92 diarrhea patients and 50 healthy individuals were collected and evaluated using direct microscopy and molecular methods to screen for bacteria, protozoa, and viruses. The prevalence of Blastocystis was 24.6% in total and more frequent in the healthy group (30.0%). The commonly detected STs (subtypes) were ST3 (40.0%) and ST2 (34.2%). The distribution of Blastocystis STs in the healthy and diarrheal groups did not show any difference in sex and age, but ST3 was detected more frequently in patients aged from 40 to 59 years (p < 0.05). Alleles 4 (8/12) and 2 (4/12) were present in ST1; 9 (3/5) and 12 (2/5) in ST2; 34 (9/14), 36 (3/14), and 38 (2/14) in ST3; and only allele 42 (2/2) in ST4. D. fragilis was present in 8.4% of the population. However, there was no statistically significant difference between the healthy and diarrheic groups (12.0% and 6.5%, respectively), neither with respect to age nor sex. Co-infection was 58.3% and was more frequent in healthy individuals (33.3%) than in diarrhea patients (25.0%). Blastocystis ST3 was the most common subtype detected, with D. fragilis at 33.3%. Salmonella, Shigella, or helminth eggs were not observed in all groups, but Entamoeba histolytica, Giardia intestinalis, Cryptosporidium, Rotavirus, Adenovirus, and Clostridium difficile toxin were found only in diarrhea patients. These findings support the hypothesis that Blastocystis and D. fragilis may be part of the healthy human gut microbiome.

Metataxomics reveals Blastocystis subtypes mixed infections in Colombian children

Blastocystis sp., is an intestinal protist with a broad host range and a high prevalence in human populations worldwide, even in developed Western countries. The publication of conflicting evidence has divided the scientific community about the pathogenic role of this parasite. Even though, genetic studies on Blastocystis sp. revealed associations between genotypes and different pathogenic profiles. Conventionally, the detection of this parasite is based on microscopic or PCR methods, which offer meager or null performance in detecting mixed infections. In this work, we applied a metataxonomic NGS approach targeting the V4 region of the eukaryotic SSU-rRNA gene and classical phylogenetic methods. This approach allowed us to detect Blastocystis sp. in stool samples from infected children living in an urban setting in the city of Medellin attending the same daycare center. Phylogenetic analysis identified the subtypes present in the children as ST1, ST2, and ST3. Besides, mixed infections of subtypes ST1 + ST3 were spotted in 16% of the analyzed stool samples.

Blastocystis infection among diarrhea outpatients in Ningbo, Southeast China: A potential zoonotic health threat

BACKGROUND

Blastocystis is one of the important zoonotic parasites which can infect humans and various animals worldwide and has become a growing global public health concern. The study aims to obtain the data of Blastocystis infection and the information of the genetic characteristic.

METHODS

In the present study, 489 fecal samples were collected from diarrhea outpatients in Ningbo, Zhejiang province, and were examined the presence of Blastocystis by polymerase chain reaction combined with sequencing.

RESULTS

A total of 10 samples (2.04%, 10/489) were positive for Blastocystis with no significant difference among sex and age groups, respectively. Eight samples were successfully sequenced, and five zoonotic ST3 and three zoonotic ST1 with two new sequences were identified.

CONCLUSIONS

We first demonstrated the occurrence of Blastocystis infection in diarrhea outpatients in Ningbo, with two zoonotic subtypes (ST1 and ST3) and two new sequences being characterized. Meanwhile, mixed infection of Blastocystis and E. bieneusi was found which indicates the importance of investigation of multiple parasites. Finally, more extensive studies will be needed to better understand the transmission of Blastocystis at human-animal-environment interface and provide evidence for the development of one health strategies for the prevention and control of such diseases.

Circulation and colonisation of Blastocystis subtypes in schoolchildren of various ethnicities in rural northern Thailand

Blastocystis is a protist of controversial pathogenicity inhabiting the gut of humans and other animals. Despite a century of intense study, understanding of the epidemiology of Blastocystis remains fragmentary. Here, we aimed to explore its prevalence, stability of colonisation and association with various factors in a rural elementary school in northern Thailand. One hundred and forty faecal samples were collected from 104 children at two time points (tp) 105 days apart. For tp2, samples were also obtained from 15 animals residing on campus and seven water locations. Prevalence in children was 67% at tp1 and 89% at tp2, 63% in chickens, 86% in pigs, and 57% in water. Ten STs were identified, two of which were shared between humans and animals, one between animals and water, and three between humans and water. Eighteen children (out of 36) carried the same ST over both time points, indicating stable colonisation. Presence of Blastocystis (or ST) was not associated with body mass index, ethnicity, birth delivery mode, or milk source as an infant. This study advances understanding of Blastocystis prevalence in an understudied age group, the role of the environment in transmission, and the ability of specific STs to stably colonise children.

Gut bacteria influence Blastocystis sp. phenotypes and may trigger pathogenicity

Whilst the influence of intestinal microbiota has been shown in many diseases such as irritable bowel syndrome, colorectal cancer, and aging, investigations are still scarce on its role in altering the nature of other infective organisms. Here we studied the association and interaction of Blastocystis sp. and human intestinal microbiota. In this study, we investigated the gut microbiome of Blastocystis sp.-free and Blastocystis sp. ST3-infected individuals who are symptomatic and asymptomatic. We tested if the expression of phenotype and pathogenic characteristics of Blastocystis sp. ST3 was influenced by the alteration of its accompanying microbiota. Blastocystis sp. ST3 infection alters bacterial composition. Its presence in asymptomatic individuals showed a significant effect on microbial richness compared to symptomatic ones. Inferred metagenomic findings suggest that colonization of Blastocystis sp. ST3 could contribute to the alteration of microbial functions. For the first time, we demonstrate the influence of bacteria on Blastocystis sp. pathogenicity. When Blastocystis sp. isolated from a symptomatic individual was co-cultured with bacterial suspension of Blastocystis sp. from an asymptomatic individual, the parasite demonstrated increased growth and reduced potential pathogenic expressions. This study also reveals that Blastocystis sp. infection could influence microbial functions without much effect on the microbiota diversity itself. Our results also demonstrate evidence on the influential role of gut microbiota in altering the characteristics of the parasite, which becomes the basis for the contradictory findings on the parasite's pathogenic role seen across different studies. Our study provides evidence that asymptomatic Blastocystis sp. in a human gut can be triggered to show pathogenic characteristics when influenced by the intestinal microbiota.

Challenges and costs of donor screening for fecal microbiota transplantations

BACKGROUND

The increasing interest to perform and investigate the efficacy of fecal microbiota transplantation (FMT) has generated an urge for feasible donor screening. We report our experience with stool donor recruitment, screening, follow-up, and associated costs in the context of clinical FMT trials.

METHODS

Potential stool donors, aged between 18-65 years, underwent a stepwise screening process starting with an extensive questionnaire followed by feces and blood investigations. When eligible, donors were rescreened for MDROs and SARS-CoV-2 every 60-days, and full rescreening every 4-6 months. The costs to find and retain a stool donor were calculated.

RESULTS

From January 2018 to August 2021, 393 potential donors underwent prescreening, of which 202 (51.4%) did not proceed primarily due to loss to follow-up, medication use, or logistic reasons (e.g. COVID-19 measures). 191 potential donors filled in the questionnaire, of which 43 (22.5%) were excluded. The remaining 148 candidates underwent parasitology screening: 91 (61.5%) were excluded, mostly due to Dientamoeba fragilis and/or high amounts of Blastocystis spp. After additional feces investigations 18/57 (31.6%) potential donors were excluded (mainly for presence of Helicobacter Pylori and ESBL-producing organisms). One donor failed serum testing. Overall, 38 out of 393 (10%) potential donors were enrolled. The median participation time of active stool donors was 13 months. To recruit 38 stool donors, €64.112 was spent.

CONCLUSION

Recruitment of stool donors for FMT is challenging. In our Dutch cohort, failed eligibility of potential donors was often caused by the presence of the protozoa Dientamoeba fragilis and Blastocystis spp.. The exclusion of potential donors that carry these protozoa, especially Blastocystis spp., is questionable and deserves reconsideration. High-quality donor screening is associated with substantial costs.

A baseline epidemiological study of the co-infection of enteric protozoans with human immunodeficiency virus among men who have sex with men from Northeast China

Background

Human immunodeficiency virus (HIV) and enteric parasite co-infection not only aggravates the clinical symptoms of parasites but also accelerates acquired immunodeficiency syndrome (AIDS) progression. However, co-infection research on men who have sex with men (MSM), the predominant high-risk population of HIV/AIDS in China, is still limited. In this study, we investigated the epidemiology of enteric parasites, risk factors, and associations with clinical significance in an MSM HIV/AIDS population in Heilongjiang Province, northeast China.

Methods

We recruited 308 MSMs HIV/AIDS patients and 199 HIV-negative individuals in two designated AIDS hospitals in Heilongjiang between April 2016 and July 2017. Fresh stool samples were collected. DNA extraction, molecular identification, and genotyping of Cryptosporidium species, Entamoeba histolytica, Cyclospora cayetanensis, Enterocytozoon bieneusi, and Blastocystis hominis were performed. Fourteen diarrhea-related pathogens were examined to exclude the influence of other bacterial pathogens on diarrhea incidence.

Results

31.5% of MSM HIV/AIDS participants were infected with at least one parasite species, a significantly higher proportion than that found in the HIV-negative individuals (2.5%). E. bieneusi presented the highest prevalence, followed by B. hominis, E. histolytica, Cryptosporidium spp., and C. cayetanensis. Warm seasons were the risk factor for parasitic infections in this population [odds ratio (OR) = 2.6, 95% CI: 1.47–4.57]. In addition, these individuals showed a higher proportion (35.8%) of present diarrhea (PD) compared with men who have sex with women (MSW) with HIV/AIDS (16.7%). The infection proportions of both Cryptosporidium spp. and E. histolytica were significantly higher in the PD. E. bieneusi infection was more prevalent in the historic diarrhea (HD) group. CD4⁺ T cell counts in the MSM patients with the above three parasites were significantly lower. New species and genotypes were found, and MSM patients had a wider range of species or genotypes.

Conclusions

Enteric parasitic infection was prevalent in the MSM HIV/AIDS population, especially in patients with present diarrhea during warm seasons. E. histolytica and B. hominis should also be considered high-risk parasites for opportunistic infections in AIDS patients in addition to Cryptosporidium spp.

Human immunodeficiency virus (HIV) and enteric parasite co-infection not only aggravates the clinical symptoms of parasites but also accelerates acquired immunodeficiency syndrome (AIDS) progression. In China, despite a large number of HIV-infected people, the data regarding co-infection with enteric intracellular parasites in this population is still sparse. In the present study, we investigated the epidemiology of Cryptosporidium spp., Enterocytozoon bieneusi, Blastocystis hominis, Entamoeba histolytica and Cyclospora cayetanensis in 384 HIV/AIDS including 308 MSM HIV/AIDS populations in two designated AIDS hospitals in Heilongjiang Province, North-East China between April 2016 and July 2017 by polymerase chain reaction. We also try to track the possible sources, risk factors, and any associations, with clinical significance, of human parasitic infections. Such knowledge will provide insights into prognosis, treatment, and preventive strategies against infections with such pathogens. The findings in this study have important implications for public health, the control of AIDS progression and control of parasitic infections.

Infection with pathogenic Blastocystis ST7 is associated with decreased bacterial diversity and altered gut microbiome profiles in diarrheal patients

Background

Blastocystis is a common protistan parasite inhabiting the gastrointestinal tract of humans and animals. While there are increasing reports characterizing the associations between Blastocystis and the gut microbiome in healthy individuals, only a few studies have investigated the relationships between Blastocystis and the gut microbiota in diarrheal patients.

Methods

The effects of a specific subtype (ST7) of Blastocystis on the composition of gut microbiota in diarrheal patients were investigated using 16S ribosomal RNA (rRNA) gene sequencing and bioinformatic analyses.

Results

Compared with diarrheal patients without Blastocystis, diarrheal patients infected with Blastocystis ST7 exhibited lower bacterial diversity. Beta diversity analysis revealed significant differences in bacterial community structure between ST7-infected and Blastocystis-free patients. The proportion of Enterobacteriaceae and Escherichia-Shigella were significantly enriched in ST7-infected patients. In contrast, the abundance of Bacteroides and Parabacteroides were more prevalent in Blastocystis-free patients.

Conclusions

The results of this study revealed, for the first time, that infection with Blastocystis ST7 is associated with lower bacterial diversity and altered microbial structure in diarrheal patients. Our study on clinical diarrheal patients is also the first to reinforce the notion that ST7 is a pathogenic subtype of Blastocystis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05435-z.

The regulatory function of Blastocystis spp. on the immune inflammatory response in the gut microbiome

Blastocystis spp. is a unicellular organism that resides in digestive tract of various vertebrates, with a worldwide distribution and a variable prevalence. For many years, Blastocystis spp. was considered a cyst of a flagellate, a fungus, or a saprophyte yeast of the digestive tract; in 1996, it is placed in the group of stramenopiles (heterokonts). Since its new classification, many questions have arisen around this protist about its role as a pathogen or non-pathogen organism. Recent evidence indicates that Blastocystis spp. participates in the immune inflammatory response in the intestinal microbiome generating an anti-inflammatory response, showing a lower concentration of fecal inflammatory markers in infected human hosts. Here, we review recent findings on the regulatory function of Blastocystis spp. in the immune inflammatory response to comprehend the purpose of Blastocystis spp. in health and disease, defining if Blastocystis spp. is really a pathogen, a commensal or even a mutualist in the human gut microbiome.

Interplay between Intestinal Bacterial Communities and Unicellular Parasites in a Morbidly Obese Population: A Neglected Trinomial

Obesity is an epidemic causing a metabolic health crisis. Herein, the interactions between the gut prokaryotic and eukaryotic communities, metabolic comorbidities and diet were studied. Stool samples from 56 subjects, 47 with type III obesity and 9 with type II obesity and cardiovascular risk or metabolic disease, were assessed for the richness, diversity and ecology of the bacterial gut community through metagenomics, together with the study of the presence of common unicellular eukaryote parasites (Blastocystis sp., Dientamoeba fragilis and Giardia intestinalis) by qPCR. Clinical information regarding metabolic comorbidities and non-alcoholic hepatic fatty liver disease was gathered. To assess the quality of the patients’ diet, each participant filled in three dietary questionnaires. The most prevalent parasite Blastocystis sp. (46.4%), together with D. fragilis (8.9%), was found to be associated with higher mean diversity indexes regarding non-colonized subjects; the opposite of that which was observed in those with G. intestinalis (16.1%). In terms of phyla relative abundance, with Blastocystis sp. and D. fragilis, very slight differences were observed; on the contrary, G. intestinalis was related to an increase in Bacteroidetes and Proteobacteria, and a decrease in Firmicutes and Actinobacteria, presenting the lowest Firmicutes/Bacteroidetes ratio. At genus level, Blastocystis sp. and/or D. fragilis was accompanied with an increase in Lactobacillus spp., and a decrease in Akkermansia spp., Bifidobacterium spp. and Escherichia spp., while G. intestinalis was associated with an increase in Bacteroides spp., and a decrease in Faecalibacterium spp., Prevotella spp. and Lactobacillus spp., and the highest Bacteroides spp./Prevotella spp. ratio. Participants with non-alcoholic hepatic fatty liver presented a higher Firmicutes/Bacteroidetes ratio, and those with type 2 diabetes displayed a significantly lower Faecalibacterium spp./Escherichia spp. ratio, due to an overrepresentation of the genus Escherichia spp. The presence of parasites was associated with variations in the richness, diversity and distribution of taxa in bacterial communities, confirming a gain in diversity associated with Blastocystis sp. and providing different functioning of the microbiota with a potential positive effect on comorbidities such as type 2 diabetes, insulin resistance and metabolic syndrome. Future basic and clinical studies should assess the beneficial or pathogenic effect of these eukaryotes on obese subjects and focus on deciphering whether they may imply a healthier metabolic profile.

Biological characterization of D-lactate dehydrogenase responsible for high-yield production of D-phenyllactic acid in Sporolactobacillus inulinus

PLA (3‐D‐phenyllactic acid) is an ideal antimicrobial and immune regulatory compound present in honey and fermented foods. Sporolactobacillus inulinus is regarded as a potent D‐PLA producer that reduces phenylpyruvate (PPA) with D‐lactate dehydrogenases. In this study, PLA was produced by whole‐cell bioconversion of S. inulinus ATCC 15538. Three genes encoding D‐lactate dehydrogenase (d‐ldh1, d‐ldh2, and d‐ldh3) were cloned and expressed in Escherichia coli BL21 (DE3), and their biochemical and structural properties were characterized. Consequently, a high concentration of pure D‐PLA (47 mM) was produced with a high conversion yield of 88%. Among the three enzymes, D‐LDH1 was responsible for the efficient conversion of PPA to PLA with kinetic parameters of Km (0.36 mM), k_cat (481.10 s⁻¹), and k_cat/Km (1336.39 mM⁻¹ s⁻¹). In silico structural analysis and site‐directed mutagenesis revealed that the Ile307 in D‐LDH1 is a key residue for excellent PPA reduction with low steric hindrance at the substrate entrance. This study highlights that S. inulinus ATCC 15538 is an excellent PLA producer, equipped with a highly specific and efficient D‐LDH1 enzyme.

Changes in Gut Microbiota Composition Associated with the Presence of Enteric Protist Blastocystis in Captive Forest Musk Deer (Moschus Berezovskii)

Blastocystis is a common protistan parasite inhabiting the gastrointestinal tract of a wide range of hosts including humans and domestic and wild animals. Many studies have revealed the associations between Blastocystis and gut microbiome in humans. However, only a few studies have focused on the associations between Blastocystis and gut microbiome of animals, especially in forest musk deer (Moschus berezovskii). We investigated the effects of the Blastocystis colonization on the intestinal bacterial community compositions using amplicon sequencing targeting the V4 variable region of the 16S rRNA. Two subtypes of Blastocystis (ST5 and ST10) and Blastocystis-free (control) were included in this study. We found that compared with the forest musk deer without Blastocystis, ST10-colonized forest musk deer had higher bacterial richness and diversity, while ST5-colonized forest musk deer showed a comparable bacterial diversity. Likewise, beta diversity revealed significant differences in bacterial community structure between ST10-colonized and Blastocystis-free forest musk deer. The proportion of Bacteroidetes were significantly enriched in ST10-colonized forest musk deer. Bacterial community structure between ST5-colonized and Blastocystis-free forest musk deer did not differ significantly. The present study explored the associations between Blastocystis and gut microbial community of forest musk deer for the first time, and revealed ST10 colonization, instead of ST5, is associated with higher bacterial diversity and shifted microbial structure. Our data provides valuable insights into the associations between gut microbiomes and parasites.

IMPORTANCE Forest musk deer is listed as an endangered species by International Union for Conservation of Nature Red List, and the Chinese government has introduced captivity breeding measures to curb the rapid decline of the musk deer population since the 1950s. It has been suggested that Blastocystis colonization can modulate the composition of the host's intestinal microbiota, thereby affecting the host health. The present study investigated the effects of the Blastocystis colonization on the gut microbiota in the feces of forest musk deer in Sichuan Province, China. Two subtypes (ST5 and ST10) have differential effects on the bacterial diversity and community composition, suggesting that the study of Blastocystis should be distinguished at the subtype level. Because the pathogenicity of Blastocystis is controversial, pathogenic, or commensal, continuous monitoring of the impact of Blastocystis colonization on the intestinal microbiota is of great significance to assess its health effects on forest musk deer.

Interactions between Blastocystis subtype ST4 and gut microbiota in vitro

BACKGROUND

Blastocystis ST4 is a common protistan parasite of the gastrointestinal tract of humans and a wide range of animals. While it has been suggested that colonization with ST4 is associated with healthy gut microbiota, how ST4 influences the gut microbiota remains poorly studied. This study aimed to examine the interactions between ST4 and several intestinal bacteria using in vitro co-culture systems, and to further investigate the mechanism of interaction and its effect on the epithelial barrier integrity of HT-29 cells.

METHODS

Seven intestinal bacteria Bacteroides fragilis, Bifidobacterium longum, Bacillus subtilis, Bacteroides vulgatus, Escherichia coli, Enterococcus faecalis, and Lactobacillus brevis were co-cultured with Blastocystis ST4 in vitro. Flow cytometry and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) were used to determine the role of reactive oxygen species (ROS) and bacteria oxidoreductase genes, respectively, in response to Blastocystis co-incubation. Transepithelial electrical resistance (TEER) and flux assays were performed to assess the effect of microbiota representatives on the integrity of the intestinal epithelial barrier.

RESULTS

Co-incubation with Blastocystis ST4 showed a beneficial influence on most intestinal bacteria, while ST4 significantly inhibited the growth of B. vulgatus, a common pathogen in the genus Bacteroides. The decrease in B. vulgatus when co-incubated with Blastocystis ST4 was associated with high levels of ROS and the upregulation of oxidative stress-related genes. Furthermore, co-incubation with Blastocystis ST4 was able to protect the intestinal epithelial barrier from damage by B. vulgatus.

CONCLUSIONS

This study demonstrated, for the first time, that Blastocystis ST4 has beneficial effects on intestinal commensal bacteria in vitro, and can inhibit the growth of pathogenic B. vulgatus. Combined with previous microbiome research on ST4, our data suggest that ST4 may be a beneficial commensal.

Relationship Among Blastocystis, the Firmicutes/Bacteroidetes Ratio and Chronic Stress in Mexican University Students

The role played by Blastocystis in humans has been a subject of discussion due to its intestinal effects and modifications in the intestinal microbiota. We aimed to analyze the relationship between Blastocystis subtypes ST1-4 and 7, the Firmicutes to Bacteroidetes ratio (F/B ratio) of fecal microbiota, and chronic stress in university students. This study had a cross-sectional design with a sample of 202 students. We analyzed fecal and hair samples, and stress inventories were applied to the students. The results showed a frequency of Blastocystis-colonized students of 52.97%. Regarding fecal microbiota, a median RAU of 0.801 for Firmicutes and 0.82 of Bacteroidetes were obtained, with an F/B ratio of 0.83. A low F/B ratio (66.04%) was more frequent in Blastocystis-colonized students, whereas a high F/B ratio (68.09%) (p =  < 0.0001) was found in the Blastocystis-non-colonized. Only Blastocystis ST3 did not significantly correlate with a low F/B ratio (p = 0.290). The ST4 was associated with lower values of cortisol (p = 0.030), psychological stress (p = 0.040), and lower frequency of constipation (p = 0.010). Only two students with the ST1 had abdominal pain (p = 0.007). Our results suggest that colonization by Blastocystis subtypes can modify the intestinal microbiota due to a decreased ratio between the two most representative phyla (F/B). Also, the results of this study show that ST4 colonization is related to a lower level of chronic stress.

Prevalence of Blastocystis and its association with Firmicutes/Bacteroidetes ratio in clinically healthy and metabolically ill subjects

BACKGROUND

Blastocystis is a typical anaerobic colon protist in humans with controversial pathogenicity and has relation with alterations in the intestinal microbiota composition (dysbiosis), whose eventual indicator is the Firmicutes/Bacteroidetes ratio (F/B ratio); this indicator is also linked to complications such as diabetes, obesity, or inflammatory bowel disease. The present study investigated the prevalence of Blastocystis and its association with Firmicutes/Bacteroidetes ratio in healthy and metabolic diseased subjects.

METHODS

Fecal and blood samples were collected consecutively from 200 healthy subjects and 84 subjects with metabolic disease; Blastocystis and its most frequent subtypes were identified by end-point PCR and the two most representative phyla of the intestinal microbiota Firmicutes and Bacteroidetes by real-time PCR.

RESULTS

The prevalence of Blastocystis in healthy subjects was 47.0, and 65.48% in subjects with metabolic disease; the most prevalent subtype in the total population was ST3 (28.38%), followed by ST1 (14.86%), ST4, ST5, and ST7 (each one of them with 14.19% respectively), and finally ST2 (8.78%). The low F/B ratio was associated with the prevalence of Blastocystis in the two cohorts FACSA (OR = 3.78 p < 0.05) and UNEME (OR = 4.29 p < 0.05). Regarding the subtype level, an association between the FACSA cohort ST1 and ST7 with low Firmicutes/Bacteroidetes ratio was found (OR = 3.99 and 5.44 p < 0.05, respectively).

CONCLUSIONS

The evident predatory role of Blastocystis over Firmicutes phylum was observed in both cohorts since the abundance of bacterial group's Bacteroidetes increases in the groups colonized by this eukaryote and, therefore, may have a beneficial effect.

Evolutionary and phylogenetic analyses of the barcoding region suggest geographical relationships among Blastocystis sp., ST3 in humans

Blastocystis sp., has 21 distinct subtypes of which ST3 thought to be the most prevalent subtype. This study aims to analyze the global variations of ST3. In total, 496 sequences with more than 400 nucleotides from Asia, Europe, Africa, and America were included in this study. Results show that allele 34 was the most prevalent allele in all continents. The lowest and highest allele diversity were observed in Europe and Africa, respectively. The nucleotide diversity ranged from 0.0077 in Europe to 0.02 in Africa, and haplotype diversity ranged from 0.461 in America to 0.6 in Africa. The haplotype network and Bayesian structure showed at least two major clusters including Asia and Europe-Africa-America. Tajima's D values for all continents were negative and statistically significant, indicating an excess of rare nucleotide variants. Similarly, the Fu's FS test showed negative values for all regions, indicating an excess of rare haplotypes. Pairwise F_ST exhibited a high genetic differentiation between Asia and other continents. Mismatch analysis for all populations showed a unimodal distribution. Our findings indicate that there are two probable major clusters of Blastocystis sp. ST3, a cluster which is shared between Europe, Africa, and America, and a cluster which is restricted to Asia.

The neglected role of Blastocystis sp. and Giardia lamblia in development of irritable bowel syndrome: A systematic review and meta-analysis

The possible role of Blastocystis sp. and Giardia lamblia infections in the development of irritable bowel syndrome (IBS) has long been controversial. In this study, we conducted a systematic review and meta-analysis to investigate whether these protozoan infections are associated with IBS development. We systematically searched international databases for all studies that reported these protozoa in IBS patients published by May 10, 2021. Studies were included in the review if they were observational studies with confirmed patients with IBS (in case-control and cross-sectional studies) or parasitic infections (cohort studies) with an appropriate control group. Pooled odds ratios (ORs) and 95% confidence intervals were estimated using a random-effects meta-analysis model for included studies. A total of 32 papers (42 datasets), including 29 papers (31 datasets) for Blastocystis sp./IBS and 11 papers (11 datasets) for G. lamblia/IBS met the eligibility criteria. Our results indicated that the individuals with Blastocystis sp. infection were significantly at a higher risk of IBS development (OR, 1.78; 95%CI, 1.29-2.44). Moreover, cohort studies indicated a significant positive association between G. lamblia infection and IBS risk (OR, 5.47; 95%CI, 4.23-7.08); while an increasing but no statistically significant risk was observed in case-control studies (OR, 1.19; 95%CI, 0.75-1.87). Our findings suggested that Blastocystis sp. and G. lamblia infections are associated with the increased risk of developing IBS. Despite these results, further studies are needed to determine the effect of these protozoa on IBS development.

Epidemiology and subtype distribution of Blastocystis in humans: A review

Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype (ST) distribution of Blastocystis have been rarely reported. Among Blastocystis STs, ST1-ST4 are common in humans, including healthy and immunodeficient populations. According to the Chi-squared (χ²) association based on the data compiled for this cross-sectional study, the presence of ST1 is associated with asymptomatic infection, whereas the presence of ST4 is associated with symptomatic infection. However, cross-sectional studies cannot clarify the potential pathogenicity of Blastocystis, unlike in vivo and in vitro studies. Poor hygiene, poor sanitation and zoonotic transmission are possible factors associated with high Blastocystis prevalence, although this protozoan may be part of the normal healthy human gastrointestinal microbiota. This review covers the prevalence, STs and distribution of Blastocystis infection in humans. Thus, future epidemiological and subtyping studies could reveal new STs in humans as well as possible associations of STs with disease, drug resistance and related mechanisms such as protease activity. These associations with proper ST identification may facilitate the control of potential threats to host health, including the direct pathogenic effects of Blastocystis or alterations of the gastrointestinal microbiome.

Parasites and diet as main drivers of the Malagasy gut microbiome richness and function

Interactions between the prokaryotic microbiome and eukaryotic parasites in the vertebrate gut may affect overall host health and disease. While intertropical areas exhibit a high rate of parasites carriers, such interactions are understudied in these populations. Our objectives were to (1) describe the gut microbiome of individuals living in Madagascar, (2) identify potential associations between bacterial taxa and parasites colonizing the digestive tract and (3) highlight main determinants of the gut microbiota composition in this developing country. Metadata (socioeconomic, diet, clinical) and fecal samples were collected from 219 volunteers from North-West Madagascar (Mahajanga). Fecal microbiome was assessed through 16S rRNA gene sequencing and metabolomics, and related to dietary habits and parasites carriage. We highlight important Malagasy gut microbiome peculiarities. Out of three detected enterotypes, only one is similar to that observed in Westernized countries (Ruminococcus-driven). Functions associated with the two others (Clostridium sensu stricto-driven and Escherichia/Shigella-driven) are mostly directed toward amino acids biosynthesis and degradation, respectively. Diet and protozoan carriage were the main drivers of microbiota composition. High protozoan carriage was associated with higher diversity, richness and microbial functionalities. The gut microbiome of Malagasy strongly differs from that of Westernized countries. Asymptomatic protozoan carriage and dietary habits are the external factors with the deepest impact on gut microbiome. Further studies are needed to understand whether gut microbial richness constitute a predilection niche for protozoans colonization, due to their gazing features, or whether the parasites themselves induce a higher bacterial richness.

Blastocystis in the faeces of children from six distant countries: prevalence, quantity, subtypes and the relation to the gut bacteriome

Background

Blastocystis is a human gut symbiont of yet undefined clinical significance. In a set of faecal samples collected from asymptomatic children of six distant populations, we first assessed the community profiles of protist 18S rDNA and then characterized Blastocystis subtypes and tested Blastocystis association with the faecal bacteriome community.

Methods

Stool samples were collected from 244 children and young persons (mean age 11.3 years, interquartile range 8.1–13.7) of six countries (Azerbaijan 51 subjects, Czechia 52, Jordan 40, Nigeria 27, Sudan 59 and Tanzania 15). The subjects showed no symptoms of infection. Amplicon profiling of the 18S rDNA was used for verification that Blastocystis was the most frequent protist, whereas specific real-time PCR showed its prevalence and quantity, and massive parallel amplicon sequencing defined the Blastocystis subtypes. The relation between Blastocystis and the stool bacteriome community was characterized using 16S rDNA profiling.

Results

Blastocystis was detected by specific PCR in 36% (88/244) stool samples and was the most often observed faecal protist. Children from Czechia and Jordan had significantly lower prevalence than children from the remaining countries. The most frequent subtype was ST3 (49%, 40/81 sequenced samples), followed by ST1 (36%) and ST2 (25%). Co-infection with two different subtypes was noted in 12% samples. The faecal bacteriome had higher richness in Blastocystis-positive samples, and Blastocystis was associated with significantly different community composition regardless of the country (p < 0.001 in constrained redundancy analysis). Several taxa differed with Blastocystis positivity or quantity: two genera of Ruminococcaceae were more abundant, while Bifidobacterium, Veillonella, Lactobacillus and several other genera were undrerrepresented.

Conclusions

Asymptomatic children frequently carry Blastocystis, and co-infection with multiple distinct subtypes is not exceptional. Prevalence and quantity of the organism clearly differ among populations. Blastocystis is linked to both faecal bacteriome diversity and its composition.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04859-3.

Gut microbiota composition in health-care facility-and community-onset diarrheic patients with Clostridioides difficile infection

The role of gut microbiota in the establishment and development of Clostridioides difficile infection (CDI) has been widely discussed. Studies showed the impact of CDI on bacterial communities and the importance of some genera and species in recovering from and preventing infection. However, most studies have overlooked important components of the intestinal ecosystem, such as eukaryotes and archaea. We investigated the bacterial, archaea, and eukaryotic intestinal microbiota of patients with health-care-facility- or community-onset (HCFO and CO, respectively) diarrhea who were positive or negative for CDI. The CDI-positive groups (CO/+, HCFO/+) showed an increase in microorganisms belonging to Bacteroidetes, Firmicutes, Proteobacteria, Ascomycota, and Opalinata compared with the CDI-negative groups (CO/-, HCFO/-). Patients with intrahospital-acquired diarrhea (HCFO/+, HCFO/-) showed a marked decrease in bacteria beneficial to the intestine, and there was evidence of increased Archaea and Candida and Malassezia species compared with the CO groups (CO/+, CO/-). Characteristic microbiota biomarkers were established for each group. Finally, correlations between bacteria and eukaryotes indicated interactions among the different kingdoms making up the intestinal ecosystem. We showed the impact of CDI on microbiota and how it varies with where the infection is acquired, being intrahospital-acquired diarrhea one of the most influential factors in the modulation of bacterial, archaea, and eukaryotic populations. We also highlight interactions between the different kingdoms of the intestinal ecosystem, which need to be evaluated to improve our understanding of CDI pathophysiology.

Human Transmission of Blastocystis by Fecal Microbiota Transplantation Without Development of Gastrointestinal Symptoms in Recipients

Background

Patients with multiple recurrent Clostridioides difficile infections (rCDI) are treated with fecal microbiota transplantation (FMT), using feces provided by healthy donors. Blastocystis colonization of donors is considered an exclusion criterion, whereas its pathogenicity is still under debate.

Methods

The introduction of molecular screening for Blastocystis sp. at our stool bank identified 2 donors with prior negative microscopies but positive polymerase chain reactions (PCRs). Potential transmission of Blastocystis sp. to patients was assessed on 16 fecal patient samples, pre- and post-FMT, by PCR and subtype (ST) analyses. In addition, clinical outcomes for the treatment of rCDI (n = 31), as well as the development of gastrointestinal symptoms, were assessed.

Results

There was 1 donor who carried Blastocystis ST1, and the other contained ST3. All patients tested negative for Blastocystis prior to FMT. With a median diagnosis at 20.5 days after FMT, 8 of 16 (50%) patients developed intestinal colonization with Blastocystis, with identical ST sequences as their respective donors. Blastocystis-containing fecal suspensions were used to treat 31 rCDI patients, with an FMT success rate of 84%. This success rate was not statistically different from patients transferred with Blastocystis sp.–negative donor feces (93%, 76/82). Patients transferred with Blastocystis sp.–positive donor feces did not report any significant differences in bowel complaints in the first week, after 3 weeks, or in the months following FMT.

Conclusions

We demonstrated the first transmission of Blastocystis ST1 and ST3 from donors to patients by FMT. This did not result in gastrointestinal symptomatology or have any significant effect on rCDI treatment outcomes.

Blastocystis subtypes in patients with diabetes mellitus from the Midwest region of Brazil

Blastocystis sp. is an enteric protist commonly found in human fecal samples. In Brazil, few studies have been developed, but none of them has explored the presence of Blastocystis in patients with diabetes mellitus. We evaluated the occurrence and molecular identification of Blastocystis sp. among patients with diabetes mellitus in the Midwest region, Goias State, Brazil. Genomic DNA was obtained from 175 fecal samples (99 from the diabetic group and 76 from the control group). PCR was performed using pan-Blastocystis primers from the SSU-rDNA gene. Microscopic examination revealed positivity of 12.1% and 7.9% for Blastocystis in diabetics and in controls, respectively. Amplification of Blastocystis DNA was observed in 34.4% (34 of 99) and 30.3% (23 of 76) from the diabetic and control groups, respectively. Phylogenetic analyses and BLAST searches revealed six subtypes among Blastocystis isolates in the diabetic group, represented by ST1 (38.2%), ST2 (11.8%), ST3 (35.3%), ST6 (2.9%), ST7 (2.9%) and ST8 (8.8%). In the control group, ST1 (21.8%), ST2 (21.8%), ST3 (43.5%), ST6 (4.4%) and ST8 (8.7%) were identified. This study is the first report regarding the occurrence and subtypes distribution of Blastocystis in patients with diabetes mellitus in Brazil. The results reinforce the potential risk of Blastocystis infection in patients with diabetes, in addition, it contributes to the understanding of the genetic diversity of this enigmatic organism.

Blastocystis Colonization Alters the Gut Microbiome and, in Some Cases, Promotes Faster Recovery From Induced Colitis

Protists are a normal component of mammalian intestinal ecosystems that live alongside, and interact with, bacterial microbiota. Blastocystis, one of the most common intestinal eukaryotes, is reported as a pathogen that causes inflammation and disease, though health consequences likely vary depending on host health, the gut ecosystem, and genetic diversity. Accumulating evidence suggests that Blastocystis is by and large commensal. Blastocystis is more common in healthy individuals than those with immune mediated diseases such as Inflammatory Bowel Diseases (IBD). Blastocystis presence is also associated with altered composition and higher richness of the bacterial gut microbiota. It is not clear whether Blastocystis directly promotes a healthy gut and microbiome or is more likely to colonize and persist in a healthy gut environment. We test this hypothesis by measuring the effect of Blastocystis ST3 colonization on the health and microbiota in a rat experimental model of intestinal inflammation using the haptenizing agent dinitrobenzene sulfonic acid (DNBS). We experimentally colonized rats with Blastocystis ST3 obtained from a healthy, asymptomatic human donor and then induced colitis after 3 weeks (short term exposure experiment) or after 13 weeks (long term exposure experiment) and compared these colonized rats to a colitis-only control group. Across experiments Blastocystis ST3 colonization alters microbiome composition, but not richness, and induces only mild gut inflammation but no clinical symptoms. Our results showed no effect of short-term exposure to Blastocystis ST3 on gut inflammation following colitis induction. In contrast, long-term Blastocystis exposure appears to promote a faster recovery from colitis. There was a significant reduction in inflammatory markers, pathology 2 days after colitis induction in the colonized group, and clinical scores also improved in this group. Blastocystis colonization resulted in a significant reduction in tumor necrosis factor alpha (TNFα) and IL-1β relative gene expression, while expression of IFNγ and IL17re/17C were elevated. We obtained similar results in a previous pilot study. We further found that bacterial richness rebounded in rats colonized by Blastocystis ST3. These results suggest that Blastocystis sp. may alter the gut ecosystem in a protective manner and promote faster recovery from disturbance.

Changes in the Human Gut Microbiota Associated With Colonization by Blastocystis sp. and Entamoeba spp. in Non-Industrialized Populations

Human gut microbial communities are mainly composed of bacteria, but also include fungi, viruses, archaea, and protozoa, whose role in the gut ecosystem has only recently begun to be recognized. For example, humans colonized by Blastocystis (a gut protozoan with controversial pathogenicity) host a more diverse bacterial microbiota than individuals not carrying it, suggesting that its presence may be beneficial for the host. In parallel, the presence of non-pathogenic Entamoeba spp. has been associated with an increased diversity and compositional shifts in the bacterial microbiota of healthy rural individuals in Cameroon. However, Entamoeba and Blastocystis, the two most prevalent human gut protozoa, have never been studied in the same individuals, preventing the study of their interaction. As Blastocystis is one of the few gut protozoa commonly found in industrialized populations, which are otherwise mostly devoid of gut eukaryotes, we need to focus on rural “traditional” populations, who harbor a higher diversity of gut eukaryotes (whether pathogenic or commensal) in order to study protozoa interactions in the gut ecosystem. To this end, we profiled the gut bacterial microbiota of 134 healthy Cameroonian adults using 16S rRNA gene amplicon sequencing data. Entamoeba and Blastocystis presence and co-occurrence pattern in the same individuals were determined using metagenomic shotgun data. We found that, when taking into account both protozoa jointly, Blastocystis was associated with both a higher richness and a higher evenness of the gut bacterial microbiota, while Entamoeba was associated only with a higher richness. We demonstrated a cumulative influence of these protozoa on bacterial microbiome diversity. Furthermore, while the abundance of several common taxa (for example, Ruminococcaceae, Coprococcus and Butyrivibrio) varied according to Blastocystis colonization, only a single Bacteroides amplicon sequence variant was found to be differentially abundant between Entamoeba-negative and Entamoeba-positive samples. Given the specific signature of each protozoan on the gut microbiota and the seemingly stronger association for Blastocystis, our results suggest that Blastocystis and Entamoeba interact with gut bacteria each in its own way, but experimental studies are needed to explore the precise mechanisms of these interactions.

New insights into the interactions between Blastocystis, the gut microbiota, and host immunity

The human gut microbiota is a diverse and complex ecosystem that is involved in beneficial physiological functions as well as disease pathogenesis. Blastocystis is a common protistan parasite and is increasingly recognized as an important component of the gut microbiota. The correlations between Blastocystis and other communities of intestinal microbiota have been investigated, and, to a lesser extent, the role of this parasite in maintaining the host immunological homeostasis. Despite recent studies suggesting that Blastocystis decreases the abundance of beneficial bacteria, most reports indicate that Blastocystis is a common component of the healthy gut microbiome. This review covers recent finding on the potential interactions between Blastocystis and the gut microbiota communities and its roles in regulating host immune responses.

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.

Comparison of DNA Extraction Methods and Real-Time PCR Assays for the Detection of Blastocystis sp. in Stool Specimens

Diagnosis of Blastocystis in stool may be challenging, as microscopic examination and culture-based methods have demonstrated low sensitivity. Molecular detection assays are now available for this enteric parasite, based on "in-house" or commercial-developed techniques. The aim of this study was to assess and compare the performance of (i) two DNA extraction methods (manual versus automated), and (ii) four qPCR assays (three "in-house" and one commercialized), for detection of Blastocystis sp. in human stools. One hundred and forty stools were included, among which 76 were confirmed to be positive for Blastocystis. The manual DNA extraction method allowed for the identification of significantly more positive specimens than the automated method (p < 0.05). In particular, specimens with a low parasite load were negative when DNA was extracted with the automated process. The four qPCR assays also had variable performances, with the commercialized assay being the most sensitive (84%) but the least specific (82%). Overall, for all qPCR assays, the specificity decreased when the sensitivity increased. Blastocystis' subtype, notably the subtype 4, influenced these performances. Our results indicate that the positivity rate for the detection of Blastocystis in stools could be variable according to the DNA extraction method and the qPCR assay used. These pitfalls need to be considered for the selection of method and interpretation of results, particularly considering the search of this intestinal parasite in a donor before fecal microbiota transplantation.

Microbiota characterization in Blastocystis-colonized and Blastocystis-free school-age children from Colombia

BACKGROUND

Blastocystis is a protist that lives in the intestinal tract of a variety of hosts, including humans. It is still unclear how Blastocystis causes disease, which presents an ongoing challenge for researchers. Despite the controversial findings on the association between Blastocystis and clinical digestive manifestations, there is currently no consensus as to whether this protozoan actually behaves as a pathogen in humans. Furthermore, the relationship between Blastocystis and the intestinal microbiota composition is not yet clear. For that reason, the aim of this study was to identify if colonization by Blastocystis is related to changes in the diversity and relative abundance of bacterial communities, compared with those of Blastocystis-free individuals in a group of Colombian children.

METHODS

We took stool samples from 57 school-aged children attending a daycare institution in Popayán (Southwest Colombia). Whole DNA was extracted and examined by 16S-rRNA amplicon-based sequencing. Blastocystis was detected by real time PCR and other intestinal parasites were detected by microscopy. We evaluated if Blastocystis was associated with host variables and the diversity and abundance of microbial communities.

RESULTS

The composition of the intestinal bacterial community was not significantly different between Blastocystis-free and Blastocystis-colonized children. Despite this, we observed a higher microbial richness in the intestines of children colonized by Blastocystis, which could, therefore, be considered a benefit to intestinal health. The phylum Firmicutes was the predominant taxonomic unit in both groups analyzed. In Blastocystis-free individuals, there was a higher proportion of Bacteroidetes; similarly, in children colonized by Blastocystis, there was a higher relative abundance of the phylum Proteobacteria; however, no statistically significant differences were found between the comparison groups.

CONCLUSIONS

The presence of Blastocystis showed a decrease in Bacteroides, and an increase in the relative abundance of the genus Faecalibacterium. It was also evident that the presence of Blastocystis was unrelated to dysbiosis at the intestinal level; on the contrary, its presence did not show statistically differences in the intestinal microbiota composition. Nevertheless, we believe that Blastocystis plays a role in the ecology of the intestinal microbiota through its interaction with other microbial components.

Contrasting microbiota profiles observed in children carrying either Blastocystis spp. or the commensal amoebas Entamoeba coli or Endolimax nana

Recent studies have shown how intestinal parasites can modulate gut microbiota. This observation is not surprising since the human intestinal lumen, like any other niche, is a battlefield of microbial competition, and Eukaryotes can affect bacterial populations. Intestinal pathogenic protist has been associated with reshaping the microbial community structure; however, the interactions between the colonic bacterial communities and parasites like Blastocystis spp., Entamoeba coli, and Endolimax nana have been poorly studied. In this work, we studied the distal intestinal bacterial microbiota of 49 children attending 7 public daycare centers in Medellin, Colombia, and compared the bacterial microbiota structure in the presence or absence of the protists Blastocystis spp., E. coli, and E. nana. Parasite colonization was associated with an increase in bacterial richness. Moreover, Blastocystis spp. presented a positive relationship with Prevotella, since this bacterium was selectively enriched in children carrying it. Remarkably, the E. coli colonized children showed a microbial profile that was closer to uninfected controls, although some bacterial taxa displayed to be enriched. This is the case for Akkermansia, which showed to be favored in E. coli colonized individuals, while notably reduced in the Blastocystis spp. parasitized group.

Molecular identification and subtypes distribution of Blastocystis sp. isolated from children and adolescent with cancer in Iran: evaluation of possible risk factors and clinical features

PURPOSE

This study aimed to determine the molecular characterization and subtype distribution of Blastocystis sp. isolated from cancer children and adolescents in Shiraz, Fars province, southwestern Iran.

METHODS

Overall, 200 fecal samples obtained from cancer children and adolescents under 18 years old (107 males and 93 females) and checked by microscopy, culture, and molecular methods (PCR). Possible etiological factors and clinical characteristics of Blastocystis infection were also evaluated and compared between Blastocystis infected and non-infected patients.

RESULTS

Thirteen of 200 (6.5%) stool samples were positive for Blastocystis by microscopy. While 21 of 200 (10.5%) were positive by culture, and 24 of 200 (12%) were positive by PCR. Out of 24 positive samples tested by PCR and sequencing, ST3 was reported as the most common subtype (nine samples, 37.5%), followed by ST2 (eight samples, 33.3%), ST1 (five samples, 20.9%), and ST7 (two samples, 8.3%). The prevalence of Blastocystis infection in males was significantly higher than females (p = 0.024). Also, Blastocystis was more prevalent in patients who had received at least eight chemotherapy cycles than fewer (p = 0.002). However, no associations were found between Blastocystis-positive rate and age, residence, type of cancers, or contact with animals. Also, there was no significant difference between frequency of Blastocystis subtypes in symptomatic and asymptomatic cancer patients.

CONCLUSIONS

Various controlled epidemiologic and topographic studies need to confirm or reject these possible associations with Blastocystis infection. The data from this study are an invaluable addition to the growing body of research studies on Blastocystis infection in cancer patients.

Association between Blastocystis and body mass index in healthy subjects; a theoretical pilot study

BACKGROUND

Blastocystis is a prevalent protozoan of the gut lumen with worldwide distribution. Recent studies showed that this microorganism may alter both richness and diversity of the gut microbiota. In the current study we assessed the dietary intakes in two Blastocystis-positive and Blastocystis-negative groups to evaluate the impact of this protozoan on the body mass index (BMI) and the dietary intakes.

METHODS

In total, ninety-three participants consisted of 17 and 76 Blastocystis-positive and Blastocystis-negative subjects, respectively, were included in this study. Positive cases of Blastocystis had been confirmed by microscopy and culture medium. Moreover, a standard FFQ was filled out for all participants and independent t-test was employed to evaluate the correlation between Blastocystis and the dietary intakes.

RESULTS

From participants, 21/93 (22.58%) and 72/93 (77.42%) were male and female, respectively. The mean age ± SD among Blastocystis-positive and Blastocystis-negative individuals was 39.41 ± 14.60 years and 37.37 ± 13.16 years, respectively. Furthermore, Blastocystis-positive participants had lower weight (67.84 ± 12.29 kg) in comparison to Blastocystis-negative individuals (69.80 ± 14.99 kg). Indeed, BMI of Blastocystis-positive subjects was 25.46 ± 4.66 and lower than Blastocystis-negative subjects 25.89 ± 5.01; (P value = 0.745).

CONCLUSIONS

Our findings showed that BMI in Blastocystis-positive subjects was lower than Blastocystis-negative persons. Blastocystis probably affects the dietary intakes and energy metabolism.

Exploring Micro-Eukaryotic Diversity in the Gut: Co-occurrence of Blastocystis Subtypes and Other Protists in Zoo Animals

Blastocystis is a genetically diverse microbial eukaryote thriving in the gut of humans and other animals. While Blastocystis has been linked with gastrointestinal disorders, its pathogenicity remains controversial. Previous reports have suggested that one out of six humans could be carrying Blastocystis in their gut, while the numbers could be even higher in animals. Most studies on Blastocystis are either exclusively targeting the organism itself and/or the associated prokaryotic microbiome, while co-occurrence of other microbial eukaryotes has been mainly ignored. Herein, we aimed to explore presence and genetic diversity of Blastocystis along with the commonly occurring eukaryotes Cryptosporidium, Eimeria, Entamoeba and Giardia in the gut of asymptomatic animals from two conservation parks in the United Kingdom. Building upon a previous study, a total of 231 fecal samples were collected from 38 vertebrates, which included 12 carnivorous and 26 non-carnivorous species. None of the animals examined herein showed gastrointestinal symptoms. The barcoding region of the small subunit ribosomal RNA was used for subtyping of Blastocystis. Overall, 47% of animal species were positive for Blastocystis. Twenty six percent of samples carried more than one subtypes, including the newly identified hosts Scottish wildcat, bongo and lynx. Fifty three percent of samples carried at least another microbial eukaryote. Herewith, we discuss potential implications of these findings and the increasingly blurred definition of microbial parasites.

First subtyping of Blastocystis sp. from pet rodents in southwestern China

Blastocystis sp. is a common eukaryotic parasite, which infects humans as well as various other animals. To date, epidemiological data regarding the detection rate and distribution of Blastocystis sp. subtypes in pet rodents are lacking in China; the present study aims to fill this gap. A total of 503 fecal samples collected from pets in different locations in southwestern China were screened for the presence of Blastocystis sp. using a nested PCR amplification of SSU rRNA method. Forty-two samples (8.35%) tested positive for Blastocystis sp. colonization. Two subtypes of Blastocystis sp. were identified based on nucleotide sequence homology and phylogenetic analysis: Blastocystis ST4 was present in 41 samples, and Blastocystis ST17 was found in 1 sample. Our results revealed robust host preference of Blastocystis ST4 and confirmed that Blastocystis ST17 can also parasitize rodents.

•

This is the first survey of Blastocystis sp. from pet rodent in southwestern of China and that 503 rodents were surveyed.

•

Forty-two samples (8.35%) tested positive for Blastocystis sp. colonization.

•

Forty-one isolates were identified as subtype ST4 and one as ST17.

•

Subtype ST4 shows a robust host preference for rodents.

Prevalence and genetic diversity of Campylobacter spp. in the production chain of broiler chickens in Lebanon and its association with the intestinal protozoan Blastocystis sp

Campylobacter jejuni is recognized as the most common foodborne pathogen associated with human gastroenteritis worldwide. Broilers are frequently infected by the bacteria and are considered the main source of exposure to humans. However, despite its public health impact, no recent data are currently available in Lebanon about Campylobacter spp. in poultry and human population. Therefore, this study aimed to determine the prevalence and genetic diversity of Campylobacter spp. in 227 ceca and on 227 carcasses of broiler chickens collected in Lebanese slaughterhouses. Overall, the prevalence of Campylobacter was shown to reach 67.0% in ceca and 17.2% on carcasses of Lebanese poultry. The only 2 Campylobacter species identified were C. jejuni and C. coli, with a slightly higher prevalence of C. coli in ceca and of C. jejuni on carcasses. A high level of genetic diversity was reported among the 51 C. jejuni isolates selected, since 25 distinct profiles were identified according to the comparative genomic fingerprinting typing method based on a subset of 40 genes using the 90% similarity threshold. Predominant clusters observed in Lebanese poultry isolates were also frequently found among French human clinical cases, highlighting that broiler chickens represent a potential reservoir for human campylobacteriosis. In addition, a significantly higher prevalence of Campylobacter spp. was found in slaughterhouse workers than in a cohort of hospitalized patients with no contact with poultry, confirming that contaminated broiler chickens in slaughterhouse appeared to be a non-negligible source of Campylobacter spp. transmission. Interestingly, a significant association between Campylobacter spp. and Blastocystis sp. has been observed. This correlation suggested that the presence of Campylobacter spp. would be favored when Blastocystis sp. is present and, similarly, the absence of one would favor the absence of the other. This is the first large-scale investigation focusing on the impact of Campylobacter spp. in broiler chickens in Lebanon and confirmed the need to implement prevention and control measures in the poultry production to reduce the burden of campylobacteriosis in the human population.

Differentiation of Blastocystis and parasitic archamoebids encountered in untreated wastewater samples by amplicon-based next-generation sequencing

Background

Application of next-generation sequencing (NGS) to genomic DNA extracted from sewage offers a unique and cost-effective opportunity to study the genetic diversity of intestinal parasites. In this study, we used amplicon-based NGS to reveal and differentiate several common luminal intestinal parasitic protists, specifically Entamoeba, Endolimax, Iodamoeba, and Blastocystis, in sewage samples from Swedish treatment plants.

Materials and methods

Influent sewage samples were subject to gradient centrifugation, DNA extraction and PCR-based amplification using three primer pairs designed for amplification of eukaryotic nuclear 18S ribosomal DNA. PCR products were sequenced using ILLUMINA® technology, and resulting sequences were annotated to species and subtype level using the in-house BION software, sequence clustering, and phylogenetic analysis.

Results

A total of 26 samples from eight treatment plants in central/southern Sweden were analysed. Blastocystis sp. and Entamoeba moshkovskii were detected in all samples, and most samples (n = 20) were positive for Entamoeba coli. Moreover, we detected Entamoeba histolytica, Entamoeba dispar, Entamoeba hartmanni, Endolimax nana, and Iodamoeba bütschlii in 1, 11, 4, 10, and 7 samples, respectively. The level of genetic divergence observed within E. nana and E. moshkovskii was 20.2% and 7.7%, respectively, across the ~400-bp region studied, and two clades of E. moshkovskii were found. As expected, Blastocystis sp. subtypes 1–4 were present in almost all samples; however, ST8 was present in 10 samples and was the only subtype not commonly found in humans that was present in multiple samples.

Conclusions

Entamoeba and Blastocystis were identified as universal members of the “sewage microbiome”. Blastocystis sp. ST8, which has been rarely reported in humans, was a very common finding, indicating that a hitherto unidentified but common host of ST8 contributed to the sewage influent. The study also provided substantial new insight into the intra-generic diversity of Entamoeba and Endolimax.

Blastocystis Colonization Is Associated with Increased Diversity and Altered Gut Bacterial Communities in Healthy Malian Children

Blastocystis is the most common protozoan colonizing the gut of vertebrates. It modulates the human digestive microbiota in the absence of inflammation and gastrointestinal disease. Although it has been associated with human diseases, including inflammatory bowel disease, its pathogenicity remains controversial. This study aimed to assess the influence of Blastocystis on the gut bacterial communities in healthy children. We conducted a cross-sectional study on 147 Blastocystis-colonized and 149 Blastocystis-noncolonized Malian children, with Blastocystis colonization assessed by real-time PCR and gut microbial communities characterized via 16S rRNA gene (Illumina MiSeq) sequencing and bioinformatics analysis. The gut microbiota diversity was higher in Blastocystis-colonized compared to Blastocystis-noncolonized children. The phyla Firmicutes, Elusimicrobia, Lentisphaerae, and Euryarchaeota were higher in Blastocystis-colonized children, whereas Actinobacteria, Proteobacteria, unassigned bacteria, and Deinococcus-Thermus were higher in Blastocystis-noncolonized children. Moreover, Faecalibacterium prausnitzii (family Ruminococcaceae) and Roseburia sp. (family Lachnospiraceae) abundance was higher in Blastocystis-colonized children. We conclude that Blastocystis colonization is significantly associated with a higher diversity of the gut bacterial communities in healthy children, while it is not associated with the presence of potentially pathogenic bacteria in the human gut.

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.

A summary of Blastocystis subtypes in North and South America

Background

Blastocystis is a stramenopile of worldwide significance due to its capacity to colonize several hosts. Based on its high level of genetic diversity, Blastocystis is classified into global ribosomal subtypes (STs). The aim of this study was to conduct a summary of Blastocystis STs and depict their distribution throughout North and South America; we did this by assembling maps and identifying its most common 18S alleles based on diverse studies that had been reported all over the continent and whose Blastocystis-positive samples were obtained from numerous hosts.

Results

Thirty-nine articles relating to nine countries from the American continent were considered, revealing that ST1 (33.3%), ST2 (21.9%), ST3 (37.9%), ST4 (1.7%), ST5 (0.4%), ST6 (1.2%), ST7 (1%), ST8 (0.7%), ST9 (0.4%), ST12 (0.3%), Novel ST (1.1%) and Mixed STs (0.2%) occurred in humans. The STs in other animal hosts were ST1 (6.5%), ST2 (6.5%), ST3 (4.7%), ST4 (7.2%), ST5 (15.9%), ST6 (17.3%), ST7 (3.6%), ST8 (20.6%), ST10 (9%), ST14 (3.6%), ST17 (1.1%) and Novel ST (4%). The countries that presented the most abundant variety of studies reporting STs were the USA with 14 STs, Brazil with 9 STs and Colombia with 8 STs. Additionally, new variants had been described in the last few years, which have increased the prevalence of these subtypes in the countries studied, such as Novel ST (1.1%) and Mixed STs (0.2%) in humans and Novel ST (4%) in animals.

Conclusions

This summary updates the epidemiological situation on the distribution of Blastocystis STs in North and South America and will augment current knowledge on the prevalence and genetic diversity of this protozoan.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3641-2) contains supplementary material, which is available to authorized users.

Metagenomics for broad and improved parasite detection: a proof-of-concept study using swine faecal samples

Efficient and reliable identification of emerging pathogens is crucial for the design and implementation of timely and proportionate control strategies. This is difficult if the pathogen is so far unknown or only distantly related with known pathogens. Diagnostic metagenomics - an undirected, broad and sensitive method for the efficient identification of pathogens - was frequently used for virus and bacteria detection, but seldom applied to parasite identification. Here, metagenomics datasets prepared from swine faeces using an unbiased sample processing approach with RNA serving as starting material were re-analysed with respect to parasite detection. The taxonomic identification tool RIEMS, used for initial detection, provided basic hints on potential pathogens contained in the datasets. The suspected parasites/intestinal protists (Blastocystis, Entamoeba, Iodamoeba, Neobalantidium, Tetratrichomonas) were verified using subsequently applied reference mapping analyses on the base of rRNA sequences. Nearly full-length gene sequences could be extracted from the RNA-derived datasets. In the case of Blastocystis, subtyping was possible with subtype (ST)15 discovered for the first known time in swine faeces. Using RIEMS, some of the suspected candidates turned out to be false-positives caused by the poor status of sequences in publicly available databases. Altogether, 11 different species/STs of parasites/intestinal protists were detected in 34 out of 41 datasets extracted from metagenomics data. The approach operates without any primer bias that typically hampers the analysis of amplicon-based approaches, and allows the detection and taxonomic classification including subtyping of protist and metazoan endobionts (parasites, commensals or mutualists) based on an abundant biomarker, the 18S rRNA. The generic nature of the approach also allows evaluation of interdependencies that induce mutualistic or pathogenic effects that are often not clear for many intestinal protists and perhaps other parasites. Thus, metagenomics has the potential for generic pathogen identification beyond the characterisation of viruses and bacteria when starting from RNA instead of DNA.

Prevalence and subtype distribution of Blastocystis in ethnic minority groups on both sides of the China-Myanmar border, and assessment of risk factors

Blastocystis is one of the most common intestinal parasites in humans worldwide. To understand its prevalence and to explore the risk factors for Blastocystis in humans in developing countries, a molecular epidemiological investigation of Blastocystis was conducted in ethnic minority groups on both sides of the China-Myanmar border. A total of 461 fecal specimens were collected from 289 Yao people in China and 172 Wa people in Myanmar, together with a questionnaire for each participant. Based on sequence analysis of the partial small subunit of ribosomal RNA (SSU rRNA) gene (barcode region or 260 bp region), an average prevalence of 6.29% (29/461) was observed, with 4.50% (13/289) in Yao people and 9.30% (16/172) in Wa people. Twenty-two Blastocystis isolates were successfully subtyped by sequence analysis of the barcode region. Three subtypes were identified: ST1 (n = 7), ST3 (n = 13) and ST4 (n = 2). A statistical difference in the prevalence of Blastocystis was only observed between children (12.37%, 12/97) and adults (4.95%, 16/323), and between not washing hands (11.02%, 14/127) and washing hands (4.76%, 15/315) after using toilets, emphasizing the importance and necessity of health education in people in the investigated areas, especially in children.

Blastocystis subtypes isolated from travelers and non-travelers from the north of Poland - A single center study

Blastocystis is a common, enteric protist of humans and animals with a worldwide distribution and unclear clinical relevance. Nine out of 17 genetically diverse subtypes occur in humans. We analysed the distribution of Blastocystis subtypes and the intensity of invasion in relation to the gastrointestinal tract disorders and travels to different continents. 122 Blastocystis stool cultures were subtyped via polymerase chain reaction (PCR) with seven pairs of subtype-specific, sequence-tagged-site (STS) primers. Five subtypes of Blastocystis were detected: ST3 (59%), ST2 (19.7%), ST1 (13.1%), ST6 (3.3%), ST7 (3.3%), and two mixed infections with ST1/ST3 (1.6%). ST1 was detected exclusively in travelers to hot climate zones and ST2 was found more frequently in people visiting other continents compared to those who never left Poland. We found no correlation between gastrointestinal tract disorders, Blastocystis STs, and parasite load. There was no age predisposition to the Blastocystis infection. We established the distribution of Blastocystis STs among Poles traveling to different continents and never leaving Poland. Our study sheds more light on the problem of importing Blastocystis infection. It shows that certain subtypes detected in Europe can be imported due to travel or migration. Collecting data on the travel history of the surveyed persons is necessary to clarify this matter.

Use of shotgun metagenomics for the identification of protozoa in the gut microbiota of healthy individuals from worldwide populations with various industrialization levels

Protozoa have long been considered undesirable residents of the human gut, but recent findings suggest that some of them may positively affect the gut ecosystem. To better understand the role and ecological dynamics of these commensal and potentially beneficial protozoan symbionts, we need efficient methods to detect them, as well as accurate estimates of their prevalence across human populations. Metagenomics provides such an opportunity, allowing simultaneous detection of multiple symbionts in a single analytical procedure. In this study, we collected fecal samples of 68 individuals from three Cameroonian populations with different subsistence modes and compared metagenomics-based and targeted methods of detection for two common protozoan genera: Blastocystis and Entamoeba. In addition, we analyzed our data along with publicly available fecal metagenomes from various worldwide populations to explore the prevalence and association patterns of ten protozoan genera. Regarding the detection method, microscopy was much less sensitive than metagenomics for Entamoeba, whereas qPCR was at least as sensitive as metagenomics for Blastocystis sp. However, metagenomics was more likely to detect co-colonizations by multiple subtypes. Out of the ten examined genera in 127 individuals from Cameroon, Tanzania, Peru, Italy or USA, only three (Blastocystis, Entamoeba and Enteromonas) had an overall prevalence exceeding 10%. All three genera were more common in less industrialized populations and their prevalence differed between continents and subsistence modes, albeit not in a straightforward manner. The majority (72.5%) of colonized individuals carried at least two protozoan species, indicating that mixed-species colonizations are common. In addition, we detected only positive and no negative association patterns between different protozoa. Despite the pitfalls of the metagenomic approach, ranging from the availability of good-quality sequencing data to the lack of standard analytical procedures, we demonstrated its utility in simultaneous detection of multiple protozoan genera, and especially its ability to efficiently detect mixed-species colonizations. Our study corroborates and expands prevalence results previously obtained for Blastocystis sp. and provides novel data for Entamoeba spp. and several other protozoan genera. Furthermore, it indicates that multiple protozoa are common residents of the healthy human gut worldwide.

A high-throughput sequencing assay to comprehensively detect and characterize unicellular eukaryotes and helminths from biological and environmental samples

BACKGROUND

Several of the most devastating human diseases are caused by eukaryotic parasites transmitted by arthropod vectors or through food and water contamination. These pathogens only represent a fraction of all unicellular eukaryotes and helminths that are present in the environment and many uncharacterized organisms might have subtle but pervasive effects on health, including by modifying the microbiome where they reside. Unfortunately, while we have modern molecular tools to characterize bacterial and, to a lesser extent, fungal communities, we lack suitable methods to comprehensively investigate and characterize most unicellular eukaryotes and helminths: the detection of these organisms often relies on microscopy that cannot differentiate related organisms, while molecular assays can only detect the pathogens specifically tested.

RESULTS

Here, we describe a novel sequencing-based assay, akin to bacterial 16S rRNA sequencing, that enables high-throughput detection and characterization of a wide range of unicellular eukaryotes and helminths, including those from taxonomical groups containing all common human parasites. We designed and evaluated taxon-specific PCR primer pairs that selectively amplify all species from eight taxonomical groups (Apicomplexa, Amoeba, Diplomonadida, Kinetoplastida, Parabasalia, Nematoda, Platyhelminthes, and Microsporidia). We then used these primers to screen DNA extracted from clinical, biological, and environmental samples, and after next-generation sequencing, identified both known and previously undescribed organisms from most taxa targeted.

CONCLUSIONS

This novel high-throughput assay enables comprehensive detection and identification of eukaryotic parasites and related organisms, from a wide range of complex biological and environmental samples. This approach can be easily deployed to many settings and will efficiently complement existing methods and provide a holistic perspective on the microbiome.

Distribution and genetic diversity of Blastocystis subtypes in various mammal and bird species in northeastern China

Background

Blastocystis is one of the most common intestinal parasites in humans and animals worldwide. At least 17 subtypes have been identified in mammals and birds. In China, although some studies have reported the occurrence of Blastocystis in humans and animals, our understanding of the role of animals in the transmission of human blastocystosis is only superficial due to a paucity of available molecular data. The aim of the present study was to understand infection rates of Blastocystis and the distribution and genetic diversity of subtypes in various mammal and bird species in northeastern China, as well as to assess the zoonotic potential of Blastocystis isolates.

Methods

A total of 1265 fresh fecal specimens (1080 from ten mammal species and 185 from eight bird species) were collected in Heilongjiang, Liaoning and Jilin provinces of China. Each specimen was examined for the presence of Blastocystis by PCR amplification and sequence analysis of the partial SSU rRNA gene.

Results

Fifty-four specimens (4.3%) were positive for Blastocystis. Birds (7.0%) had a higher infection rate of Blastocystis than mammals (3.8%). Blastocystis was found in seven mammal species, reindeer (6.7%), sika deer (14.6%), racoon dogs (7.5%), Arctic foxes (1.9%), dogs (2.9%), rats (3.7%) and rabbits (3.3%), as well as three bird species, pigeons (2.1%), chickens (13.0%) and red crowned cranes (14.0%). Eight subtypes were identified including ST1 (n = 5), ST3 (n = 3), ST4 (n = 13), ST6 (n = 8), ST7 (n = 6), ST10 (n = 13), ST13 (n = 4) and ST14 (n = 2). 64.8% (35/54) of Blastocystis isolates belonged to potentially zoonotic subtypes.

Conclusions

To our knowledge, this is the first report of Blastocystis in reindeer (ST10 and ST13), rabbits (ST4), racoon dogs (ST3) and Arctic foxes (ST1, ST4 and ST7). The findings of potentially zoonotic subtypes suggest that the animals infected with Blastocystis might pose a threat to human health. These data will improve our understanding of the host range and genetic diversity of Blastocystis, and also help develop efficient control strategies to intervene with and prevent the occurrence of human blastocystosis in the investigated areas.

Prevalence and subtype distribution of Blastocystis sp. isolates from poultry in Lebanon and evidence of zoonotic potential

BACKGROUND

Blastocystis sp. is a common protozoan parasite frequently identified in the digestive tract of humans and a large variety of animal hosts worldwide, including birds. It exhibits a large genetic diversity with the identification of 17 subtypes (STs), most of them with low host specificity. ST6 and ST7 were identified in birds and suggested to represent avian STs only in the context of scarce small-scale epidemiological surveys. Moreover, these two STs also account for a significant proportion of human infections whose zoonotic origin has never been clearly confirmed. Therefore, molecular screening of Blastocystis sp. was conducted by quantitative real-time PCR for fecal samples from poultry farms and their in-contact humans from slaughterhouses in Lebanon. In parallel, a control group consisting of patients hospitalized in the same geographical area and reporting no contact with poultry was also screened for the presence of the parasite.

RESULTS

The overall prevalence of Blastocystis sp. was shown to reach around 32% in chicken samples and 65% in the farms screened. All the avian isolates were subtyped and belonged to either ST6 or ST7, with a large predominance of ST6. Fifty-four percent of slaughterhouse staff members were positive for Blastocystis sp. compared with a similar prevalence of 56% in hospitalized patients. ST3 was predominant in both human cohorts followed by either ST1 then ST2 among slaughterhouse staff or by ST2 then ST1 among hospitalized patients. ST6 was also identified in two slaughterhouse workers and not in the group of hospitalized patients. Gene sequence identity was observed between chicken and human ST6 isolates from the same slaughterhouse.

CONCLUSIONS

Our data revealed a high prevalence of Blastocystis sp. in chicken samples and confirmed that ST6 and ST7 represented avian-adapted STs. Among both human cohorts, Blastocystis sp. infection was shown to exceed 50% with a predominance of ST3. The identification of ST6 in slaughterhouse staff members confirmed the zoonotic transmission of this ST through repeated and direct contact between chickens and their handlers.