Low prevalence of Blastocystis sp. in active ulcerative colitis patients

Transient colonization with Blastocystis spp. after transmission via fecal microbiota transplantation

BACKGROUND

The pathogenicity of Blastocystis spp. is still debated. Guidelines for feces donor screening differ in their advice to screen for Blastocystis spp., but when tested, its presence is a common reason for exclusion. Blastocystis spp. are correlated to increased bacterial alpha-diversity and distinct bacterial groups and therefore its presence may indicate favorable efficacy of fecal microbiota transplantation (FMT). The latest European consensus report no longer advices rejecting feces donors testing positive for Blastocystis spp. Only one paper has been published on human transmission of Blastocystis spp. via frozen FMT.

OBJECTIVE

To investigate the transmission and long-term effects of Blastocystis-positive FMT, prepared with fresh (i.e., unfrozen) feces.

METHODS

In a trial (NCT03074227) on FMT for refractory Irritable Bowel Syndrome (IBS), adolescents (age 16-20 years) received two administrations - at baseline and after 6 weeks - of fresh allogeneic FMT from a Blastocystis-positive donor via nasoduodenal tube. The follow-up was 48 weeks. Blastocystis spp. presence, viability and subtyping were determined using microscopy, culture, PCR and sequencing.

RESULTS

Three recipients received FMT from one donor colonized with Blastocystis subtype 3 (ST3). At baseline, two recipients were negative for Blastocystis spp. and one recipient carried ST2. Culturing revealed viable Blastocystis spp. in fresh donor feces but not in frozen samples. After FMT with fresh feces, the two prior-negative recipients tested positive for the donor's ST3 at 12 weeks, but had lost this subtype by week 24 and 48. The recipient initially colonized with ST2 remained colonized with ST2 and did not acquire ST3. Transient adverse events occurred, but did not differ from patients treated with Blastocystis-negative FMT. No FMT-related serious adverse events emerged.

CONCLUSION

We present the first long-term data on viable Blastocystis spp. transmission via fresh FMT in three cases. Transient colonization with Blastocystis spp. was observed, without serious FMT-related adverse events.

The Role of Blastocystis spp. in the Etiology of Gastrointestinal and Autoimmune Diseases

Blastocystis spp. has been linked to gastrointestinal symptoms, yet its pathogenicity remains uncertain. In addition, the roles of virulence factors, pathogenic potential, and host-specific traits associated with symptomatic infections are still not well understood. The growing number of immunocompromised patients has contributed to an increasing prevalence of Blastocystis spp. infections, which may be implicated in the development of various inflammatory diseases, including irritable bowel syndrome (IBS), colorectal cancer, and autoimmune disorders such as Hashimoto's disease and ulcerative colitis. However, the presence of nonspecific symptoms often complicates diagnosis. This study aimed to present current data on the impact of Blastocystis spp. on the development and progression of gastrointestinal and autoimmune diseases, as well as to explore potential treatment options for Blastocystis spp. infections. A literature review was conducted to analyze the role of Blastocystis spp. in the pathogenesis of specific diseases and to investigate potential mechanisms of its interaction with the host organism. Advances in diagnostic techniques, particularly PCR, allow not only for the detection of Blastocystis spp. but also for the identification of specific subtypes, improving treatment precision. Beyond conventional therapies like metronidazole, there is a growing emphasis on alternative treatments, including the use of medicinal plants and probiotics.

Blastocystis hominis; Friend or Foe

Blastocystis hominis (B. hominis) remains the most common parasite identified through stool examination. A clinician will undoubtedly encounter the presence of this parasite numerous times in their career. Thus, it is vital to know if this organism is a 'friend or foe', or in other words, whether it is a commensal or a pathogen. This will help clinicians decide whether to treat or not. This literature review discusses the best available evidence of the association of B. hominis and two diseases- irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). Particularly, focus has been paid to the effect of antimicrobial therapy in improving disease activity/symptoms and concluding on the pathogenicity of B. hominis based on in vitro, observational studies, and randomized controlled trials. Most importantly, the review presents a concise set of recommendations for when and how to treat B. hominis in a patient presenting gastrointestinal ailments.

Inflammatory Bowel Disease: A Comprehensive Analysis of Molecular Bases, Predictive Biomarkers, Diagnostic Methods, and Therapeutic Options

In inflammatory bowel diseases (IBDs), such as Crohn's disease (CD) and ulcerative colitis (UC), the immune system relentlessly attacks intestinal cells, causing recurrent tissue damage over the lifetime of patients. The etiology of IBD is complex and multifactorial, involving environmental, microbiota, genetic, and immunological factors that alter the molecular basis of the organism. Among these, the microbiota and immune cells play pivotal roles; the microbiota generates antigens recognized by immune cells and antibodies, while autoantibodies target and attack the intestinal membrane, exacerbating inflammation and tissue damage. Given the altered molecular framework, the analysis of multiple molecular biomarkers in patients proves exceedingly valuable for diagnosing and prognosing IBD, including markers like C reactive protein and fecal calprotectin. Upon detection and classification of patients, specific treatments are administered, ranging from conventional drugs to new biological therapies, such as antibodies to neutralize inflammatory molecules like tumor necrosis factor (TNF) and integrin. This review delves into the molecular basis and targets, biomarkers, treatment options, monitoring techniques, and, ultimately, current challenges in IBD management.

Detection of Blastocystis sp. in ulcerative colitis, Crohn's and chronic diarrheal patients by microscopy, culture and real-time polymerase chain reaction

Blastocystis sp. is a zoonotic parasite that is common in humans and animals and settles in the large intestine. The parasite can cause various gastrointestinal system complaints such as indigestion, diarrhea, abdominal pain, bloating, nausea and vomiting. The aim of this study is to determine the distribution of Blastocystis in patients diagnosed with ulcerative colitis, Crohn's and diarrhea from the gastroenterology outpatient clinic and to compare the diagnostic value of the most preferred methods. A total of 100 patients, 47 men and 53 women, were included in the study. Of the cases, 61 had diarrhea, 35 had ulcerative colitis (UC) and four had Crohn's disease. Stool samples of the patients were analyzed by as direct microscopic examination (DM), culture and real-time polymerase chain reaction (qPCR). A total of 42% positivity was detected, 29% positivity in DM and trichrome staining, 28% in culture and 41% in qPCR. 40.4% (20/47) of men and 37.7% (22/53) of women were found to be infected. Blastocystis sp. was found in 75% of Crohn's, 42.6% of diarrheal and 37.1% of UC patients. Diarrhea cases are more common with UC and there is a close relationship between Crohn's and Blastocystis positivity. While DM and trichrome staining showed a sensitivity of 69%, PCR test was found to be the most sensitive diagnostic method with approximately 98%. Diarrhea and UC are often seen together. A close relationship was detected between Crohn's disease and Blastocystis. High prevalence of Blastocystis in cases with clinical symptoms reveals the importance of the parasite. There is a need for studies on the pathogenicity of Blastocystis sp. in various gastrointestinal cases, and it is thought that molecular techniques should be used since PCR is seen to be a much more sensitive.

Commensal Intestinal Protozoa-Underestimated Members of the Gut Microbial Community

The human gastrointestinal microbiota contains a diverse consortium of microbes, including bacteria, protozoa, viruses, and fungi. Through millennia of co-evolution, the host-microbiota interactions have shaped the immune system to both tolerate and maintain the symbiotic relationship with commensal microbiota, while exerting protective responses against invading pathogens. Microbiome research is dominated by studies describing the impact of prokaryotic bacteria on gut immunity with a limited understanding of their relationship with other integral microbiota constituents. However, converging evidence shows that eukaryotic organisms, such as commensal protozoa, can play an important role in modulating intestinal immune responses as well as influencing the overall health of the host. The presence of several protozoa species has recently been shown to be a common occurrence in healthy populations worldwide, suggesting that many of these are commensals rather than invading pathogens. This review aims to discuss the most recent, conflicting findings regarding the role of intestinal protozoa in gut homeostasis, interactions between intestinal protozoa and the bacterial microbiota, as well as potential immunological consequences of protozoa colonization.

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.

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.

Detection of Blastocystis Subtypes in Children with Functional Abdominal Pain and Celiac Disease in Çorum, Turkey

BACKGROUND

Blastocystis has been associated with various symptoms of the gastrointestinal tract. We aimed to investigate the prevalence of Blastocystis in children with celiac disease (CeD) or functional abdominal pain (FAP) and to evaluate its subtypes (STs) with respect to demographic, socioeconomic and epidemiological factors.

METHODS

Overall, 161 fecal samples were collected from healthy children and patients with FAP or CeD in Hitit University Erol Olçok Research and Training Hospital, Corum, Turkey between 2016-2018. Samples were examined using both native-Lugol (NL) and trichrome-stained (TS) smears, and further analyses by PCR and Sanger sequencing were performed. A standard questionnaire was applied to obtain demographic, socioeconomic, epidemiological data.

RESULTS

Blastocystis was found in 10.6% of the total study population. Neither bacteria nor any other parasites were found, except for one Giardia (0.6%) in the CeD group. The presence/absence of the parasite was not found to be associated with demographic, socioeconomic and epidemiological factors. Blastocysis was detected in 11.5% (6/52) of the CeD, 7.7% (4/52) of the FAP, and 12.3% (7/57) of the healthy group. Diagnostic methods were similar in terms of Blastocystis detection (P= 0.671), and there was fair agreement between the NL, TS and PCR (Fleiss' Kappa=0.847, P=0.001). ST2 (42.8%) and ST3 (35.7%) were the predominant STs followed by ST1 (21.4%).

CONCLUSION

We observed no difference between study groups in terms of Blastocystis prevalence. ST1, ST2 and ST3 subtypes were detected. Blastocystis prevalence and STs were not related to any of the demographic, socioeconomic and epidemiological factors.

The Neglected Gut Microbiome: Fungi, Protozoa, and Bacteriophages in Inflammatory Bowel Disease

The gut microbiome has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Studies suggest that the IBD gut microbiome is less diverse than that of the unaffected population, a phenomenon often referred to as dysbiosis. However, these studies have heavily focused on bacteria, while other intestinal microorganisms-fungi, protozoa, and bacteriophages-have been neglected. Of the nonbacterial microbes that have been studied in relation to IBD, most are thought to be pathogens, although there is evidence that some of these species may instead be harmless commensals. In this review, we discuss the nonbacterial gut microbiome of IBD, highlighting the current biases, limitations, and outstanding questions that can be addressed with high-throughput DNA sequencing methods. Further, we highlight the importance of studying nonbacterial microorganisms alongside bacteria for a comprehensive view of the whole IBD biome and to provide a more precise definition of dysbiosis in patients. With the rise in popularity of microbiome-altering therapies for the treatment of IBD, such as fecal microbiota transplantation, it is important that we address these knowledge gaps to ensure safe and effective treatment of patients.

Prevalence of Intestinal Protozoan Infection in Patients with Ulcerative Colitis (UC) in Isfahan, Iran

Background:

Determination of the prevalence of intestinal protozoan infection is a fundamental step to set up an effective control program to improve the health status of society and to establish efficient strategies. Intestinal pathogen and even non-pathogen protozoa consider as major causes of disease in patients with gastrointestinal problems. The objective of this study is to determine the prevalence of intestinal protozoan infection in patients with ulcerative colitis (UC) in Isfahan, Iran.

Methods:

The descriptive cross-sectional study carried out from 2013 to 2018 in Isfahan, Iran. One thousand nine hundred and sixty-five samples of feces from patients with UC collected and each sample examined using direct wet mounting with normal saline and iodine and sedimentation tests such as formol-ethyl acetate concentration and trichrome-staining methods.

Results:

From 655 patients, 185 (28.2%) infected with Giardia lamblia followed by Blastocystis hominis (27.3%), Endolimax nana (14.4%), Entamoeba coli (11.5%), Iodamoba butschlii (4.7%), Entamoeba histolytica (1.4%), and Chilomastix mesnili (0.6%).

Conclusions:

This study revealed a high prevalence of infection with at least one or six non-pathogenic and pathogenic intestinal protozoa in UC patients in the Isfahan region. Intestinal protozoa are a challenging public health problem wherever health care is limited in the area. The emergence of UC in the world results in the need to study etiologic factors. In order to obtain further information about the etiology of disease, we investigated the prevalence of intestinal protozoan infection in patients with UC in Isfahan, Iran.

Subtype analysis and prevalence of mixed subtype infection of Blastocystis in farmed pigs from Chiba Prefecture, Japan

Blastocystis is an intestinal eukaryotes found in a wide range of animals and in the human population globally. Blastocystis is reported in domestic pigs, with subtype (ST) 5 being the dominant ST, followed by ST1 and ST3. The common method used for ST identification in pigs is PCR-sequencing, which often results in underestimation of the prevalence of mixed infections. Here, we aimed to investigate the ST distribution and the prevalence of mixed ST infection of Blastocystis in pigs from Chiba Prefecture in eastern Japan. A total of 82 fecal samples positive for Blastocystis were collected from two different farms, A and B. PCR was performed with subtype-specific primers, ST1, ST2, ST3, and ST5. The prevalence of single ST5 infection was 37.8% (31/82), whereas mixed infection with ST5 and other STs was 57.3% (47/82). A high percentage of single ST5 infection was observed in sows, piglets, and weaners from farm A (13/15, 86.7%), whereas mixed infection of ST5 and other STs, ST1 and ST3, was observed in 3-5-month-old grower pigs (15/18, 83.3%). Similarly, in farm B, the majority of sows and piglets under 1 month of age showed a single ST5 infection (12/17, 70.6%), whereas weaner, grower, and finisher pigs showed mixed infections with ST5 and other STs, ST1, ST2 and ST3 (27/28, 96.4%). In domestic pigs, diet and rearing environment changes dramatically over the course of animal's lifetime, which may have caused this difference in the prevalence of mixed ST infection among different age groups.

Prevalence and associated risk factors of intestinal parasitic infections among Egyptian patients with inflammatory bowel disease

The global prevalence of inflammatory bowel disease (IBD) is continuously rising, however, a little is known concerning intestinal parasitic infections (IPIs) and (IBD). We aimed to evaluate the prevalence of IPIs among IBD patients, through a case-control study and also, to correlate the positive cases to the socio-demographic risk factors of IPIs among the study groups. A 1-year case-control study included patients with IBD (n=125) and healthy controls (n=125). The fecal samples were examined with the classical parasitological methods for intestinal parasites. Also, in-vitro culture (for Blastocystis sp.) and Immuno-chromatography technique (for Cryptosporidium / Giardia /Entamoeba) were done. IBD patients had significant higher positivity rate of IPIs compared to healthy controls (Adjusted OR= 9.60, 95% CI: 4.51-20.41, P = 0.0001), with Blastocystis sp., Entamoeba dispar/ histolytica and Cryptosporidium sp. being highly significant in IBD patients. In addition to IBD, living in rural area, with low socio-economic stander, and consumed raw/contaminated food and age group > 50 years old were significant risk factors for IPIs. In conclusion, our results support a possible link between IPIs and IBD.

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.

The effect of Blastocystis sp. and Dientamoeba fragilis on psychological symptom severity in a sample of clinically diverse males and females

Health outcomes associated with Blastocystis sp. and Dientamoeba fragilis are disparate and controversial, ranging from health benefits, to years of asymptomatic carriage, through to severe illness. Evidence that Blastocystis sp. and D. fragilis are commensal members of the gut microbiota is growing. Despite this, little to no research exists investigating the potential effect of these protozoa on psychological symptom expression. As such, the aim of this retrospective cross-sectional study was to be the first to investigate the effect of protozoan carriage on severity of Depressive, Neurocognitive, Stress and Anxiety, and Sleep and Fatigue symptoms, and whether this effect changes as a function of sex. The prevalence of D. fragilis was significantly higher in females compared to males, however there were no sex differences in prevalence for Blastocystis sp. (data used in the current study contained ST1, ST3, and Blastocystis ST unspecified) or co-carriage of the two. Females reported significantly more severe symptoms across all four psychological domains compared to males. There was no significant interaction between sex and Blastocystis sp. carriage on psychological symptom severity, and no significant main effect of Blastocystis sp. on symptom severity compared to those who tested negative for protozoa. When investigating the sexes separately, there was no effect of protozoan carriage on psychological symptom expression in either males or females. These findings add weight to the argument that Blastocystis sp. and D. fragilis are not necessarily pathogenic and are likely to be part of a diverse gut (which is typically associated with better health outcomes). Further research is required given that protozoan members of the gut microbiota have been largely ignored in brain-gut-microbiota axis research.

Levodopa/dopa decarboxylase inhibitor associated microscopic colitis: An under-recognized drug reaction

BACKGROUND

Microscopic colitis is a form of inflammatory bowel disease characterized by profuse non-bloody watery diarrhea. Macroscopic abnormality is not present on colonoscopy, and it requires biopsy for diagnosis. Few cases have been attributed to levodopa/dopa-decarboxylase inhibitor therapy.

METHOD

A retrospective cohort study of 21 patients on levodopa/benserazide and one patient on levodopa-carbidopa intestinal gel with clinically suspected or biopsy proven microscopic colitis.

RESULTS

All 21 patients on oral levodopa/benserazide had resolution of diarrhea with cessation of the medication. Four patients discontinued levodopa permanently. Two were rechallenged with levodopa/benserazide without symptom recurrence. One patient on oral levodopa/carbidopa developed diarrhea only with intermittent dispersible levodopa/benserazide. 14 were switched to levodopa/carbidopa with resolution of diarrhea in 9 but symptom recurrence in 5. One patient on oral levodopa/benserazide developed profuse diarrhea when switched to levodopa-carbidopa intestinal gel. Of 7/22 patients who had colonoscopy and biopsy, 5 had histopathological proven microscopic colitis.

CONCLUSION

levodopa/dopa-decarboxylase inhibitor induced microscopic colitis may be more common than previously suspected, with the potential to affect treatment compliance and therapeutic options.

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.

Intestinal protozoa and helminths in ulcerative colitis and the influence of anti-parasitic therapy on the course of the disease

PURPOSE

The aim of this study is to determine the prevalence of intestinal helminths and protozoa in patients with ulcerative colitis (UC) and to estimate the influence of the anti-parasitic therapy on the course of the disease.

METHODS

The study was conducted at the Research Institute of Epidemiology, Microbiology and Infectious Diseases and Coloproctology Department of the Republic Clinical Hospital №1 of the Ministry of Health of the Republic of Uzbekistan. One hundred UC patients and 200 healthy individuals were examined by triple coproscopy. Additionally, 20, 25 and 22 UC patients with Blastocystis infection were treated with nitazoxanide (1.0 g/day), mesalazine (1.5-2 g/day) or a combination of nitazoxanide (1.0 g/day) and mesalazine (≥1.5-2 g/day) for 14 consecutive days, respectively. Parasitological, clinical and endoscopic examinations were conducted before therapy, immediately after and 6 and 12 weeks after therapy completion.

RESULTS

The overall prevalence of helminths in UC patients and control individuals was not significantly different: 14±3.4% and 8.5±1.9%, respectively (OR: 1.7524; 95% CI: 0.8258 to 3.7186; P=0.1). Giardia lamblia was the most prevalent parasite in both groups, but the difference compared to the control was insignificant (OR: 0.4565; 95% CI: 0.2020 to 1.0318; P=0.05). A significantly higher prevalence of Blastocystis sp., Chilomastix mesnili and Iodamoeba butschlii in UC patients compared to control individuals was found (P<0.0005): 65.0%, 14.0% and 22.0%, respectively. During all follow-up periods, the clinical response and clinical remission were not statistically different between the groups (P>0.05). Mucosal healing immediately and 6 weeks after therapy with a combination of nitazoxanide with mesalazine was significantly better than with a monotherapy of nitazoxanide, respectively (P<0.05). UC patients treated with a combination of nitazoxanide with mesalazine showed better mucosal healing than in patients treated with a monotherapy of mesalazine (P>0.05).

CONCLUSIONS

Diagnosis of Blastocystis sp. should be introduced in the complex examination of UC patients. Further clinical studies are necessary for assessment of the efficiency of anti-Blastocystis therapy in UC patients.

Worldwide prevalence of emerging parasite Blastocystis in immunocompromised patients: A systematic review and meta-analysis

BACKGROUND

Blastocystis is one of the most common pathogens of the human intestine, caused by an emerging parasite, which can lead to severe symptoms and even death in immunocompromised patients. We aimed to determine the global prevalence of Blastocystosis infection in people with immunodeficiency. A systematic literature search was conducted on Web of Science, Scopus, Google scholar, Science Direct and MEDLINE databases to select all observational studies reporting the prevalence of Blastocystosis infection in Worldwide, based on different diagnostic methods in immunocompromised patients of any age and published from inception to February 2019. Pooled estimates and 95% confidence intervals (95% CIs) were calculated using random effects models and in addition, the I² statistic was calculated. The geographic distribution of studies was evaluated and the diagnosis of Blastocystis was compared by various techniques. Electronic databases were reviewed for Blastocystosis infection in HIV/AIDS, cancer and other immunocompromised patients, and meta-analyses were conducted to calculate the overall estimated prevalence. Total68 eligible studies were included. The estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% (95% CI, 7-13%; I² 96.04%) (P < 0.001), of whom 21% [18-25] were in Australia, 12% [4-24] in America, 11% [6-17] in Europe and 10% [5-15], 7% [3-13] in Asia and Africa, respectively. It was calculated that the estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% and the prevalence estimates ranged from 0.44 to 72.39. Also, overall the prevalence of parasites co-infection in immunocompromised patients was detected as 0.024%. Our finding showed that immunocompromised people show a high prevalence of Blastocystosis infection compared to the control population. Adequate information on the prevalence rate is still missing from many countries. However, current information underscore that Blastocystis should not be neglected.

A Study on the Prevalence and Subtype Diversity of the Intestinal Protist Blastocystis sp. in a Gut-Healthy Human Population in the Czech Republic

Blastocystis sp. is a common intestinal protist colonizing the human intestine the prevalence of which varies across non-industrialized and industrialized countries. Its role in the human gut ecosystem remains unclear due to persisting gaps in knowledge of epidemiology and factors affecting gut colonization. Here, we aimed to expand the knowledge of the epidemiology of Blastocystis sp. in the gut-healthy humans in one of the industrialized European countries, including the distribution of its subtypes, the correlation between its occurrence and several factors such as lifestyle, contact with animals, age, and sex. A total of 288 stool samples were obtained from asymptomatic individuals over the entire age-range and 136 samples from animals with which the volunteers were in frequent contact. All samples were examined in parallel by PCR and xenic in vitro culture. Blastocystis sp. was detected in samples from both human and non-human hosts. In humans, the overall prevalence was 24% and eight subtypes were found; in animals, the prevalence was 10%, and only five subtypes were detected. A higher incidence of Blastocystis sp. was observed in individuals (i) traveling outside Europe, (ii) in frequent contact with livestock, and (iii) over 50 years of age. We found no effect on gender on Blastocystis sp. colonization.

Summary

This study provides data on the prevalence and diversity of the gut protist Blastocystis sp. and its subtypes in a gut-healthy human population with emphasis on several factors such as contact with animals, lifestyle, age, and gender.

Strategies and advancements in human microbiome description and the importance of culturomics

The human microbiota gained a big interest among the scientific community with numerous studies being performed to better understand its role in health and diseases. Even with all the success achieved in studying the bacterial populations at the different body sites and its interaction among each other and with the host, some links remain missing and might have therapeutic benefits. In this review, we summarize the main means used for bacterial identification, human microbiota description and the role of culturomics in leading the way towards the development of new bacterio-therapeutic approaches.

Parasite-bacteria interrelationship

Parasites and bacteria have co-evolved with humankind, and they interact all the time in a myriad of ways. For example, some bacterial infections result from parasite-dwelling bacteria as in the case of Salmonella infection during schistosomiasis. Other bacteria synergize with parasites in the evolution of human disease as in the case of the interplay between Wolbachia endosymbiont bacteria and filarial nematodes as well as the interaction between Gram-negative bacteria and Schistosoma haematobium in the pathogenesis of urinary bladder cancer. Moreover, secondary bacterial infections may complicate several parasitic diseases such as visceral leishmaniasis and malaria, due to immunosuppression of the host during parasitic infections. Also, bacteria may colonize the parasitic lesions; for example, hydatid cysts and skin lesions of ectoparasites. Remarkably, some parasitic helminths and arthropods exhibit antibacterial activity usually by the release of specific antimicrobial products. Lastly, some parasite-bacteria interactions are induced as when using probiotic bacteria to modulate the outcome of a variety of parasitic infections. In sum, parasite-bacteria interactions involve intricate processes that never cease to intrigue the researchers. However, understanding and exploiting these interactions could have prophylactic and curative potential for infections by both types of pathogens.

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.

Human microbiome and homeostasis: insights into the key role of prebiotics, probiotics, and symbiotics

The interest in the study of the gut microbiome has grown exponentially. Indeed, its impact on health and disease has been increasingly reported, and the importance of keeping gut microbiome homeostasis clearly highlighted. However, and despite many advances, there are still some gaps, as well as the real discernment on the contribution of some species falls far short of what is needed. Anyway, it is already more than a solid fact of its importance in maintaining health and preventing disease, as well as in the treatment of some pathologies. In this sense, and given the existence of some ambiguous opinions, the present review aims to discuss the importance of gut microbiome in homeostasis maintenance, and even the role of probiotics, prebiotics, and symbiotics in both health promotion and disease prevention.

Australian consensus statements for the regulation, production and use of faecal microbiota transplantation in clinical practice

OBJECTIVE

Faecal microbiota transplantation (FMT) has proved to be an extremely effective treatment for recurrent Clostridioides difficile infection, and there is interest in its potential application in other gastrointestinal and systemic diseases. However, the recent death and episode of septicaemia following FMT highlights the need for further appraisal and guidelines on donor evaluation, production standards, treatment facilities and acceptable clinical indications.

DESIGN

For these consensus statements, a 24-member multidisciplinary working group voted online and then convened in-person, using a modified Delphi approach to formulate and refine a series of recommendations based on best evidence and expert opinion. Invitations to participate were directed to Australian experts, with an international delegate assisting the development. The following issues regarding the use of FMT in clinical practice were addressed: donor selection and screening, clinical indications, requirements of FMT centres and future directions. Evidence was rated using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system.

RESULTS

Consensus was reached on 27 statements to provide guidance on best practice in FMT. These include: (1) minimum standards for donor screening with recommended clinical selection criteria, blood and stool testing; (2) accepted routes of administration; (3) clinical indications; (4) minimum standards for FMT production and requirements for treatment facilities acknowledging distinction between single-site centres (eg, hospital-based) and stool banks; and (5) recommendations on future research and product development.

CONCLUSIONS

These FMT consensus statements provide comprehensive recommendations around the production and use of FMT in clinical practice with relevance to clinicians, researchers and policy makers.

Gut Microbiota beyond Bacteria-Mycobiome, Virome, Archaeome, and Eukaryotic Parasites in IBD

The human microbiota is a diverse microbial ecosystem associated with many beneficial physiological functions as well as numerous disease etiologies. Dominated by bacteria, the microbiota also includes commensal populations of fungi, viruses, archaea, and protists. Unlike bacterial microbiota, which was extensively studied in the past two decades, these non-bacterial microorganisms, their functional roles, and their interaction with one another or with host immune system have not been as widely explored. This review covers the recent findings on the non-bacterial communities of the human gastrointestinal microbiota and their involvement in health and disease, with particular focus on the pathophysiology of inflammatory bowel disease.

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.

Fecal microbiota transplantation donation: the gift that keeps on giving

Fecal microbiota transplantation (FMT) is being studied and utilized for various medical conditions including Clostridium difficile colitis, inflammatory bowel diseases (IBD), obesity, myasthenia gravis, and so on. Yet, FMT donation, whether from an individual or a stool bank, can be challenging given the numerous requirements and donor costs. Furthermore, data outcomes on recipients of FMT regarding donor's health co-morbidities, age, and weight are limited but emerging. The purpose of this review is to evaluate cost, safety, and accessibility in FMT donation.

Oropharyngeal microbiome of an HIV-positive patient

Studies on understanding the human microbiome continue to grow rapidly; nonetheless, reports on alterations in the microbiome post HIV infection are limited. Human microbiome is an aggregate of bacteria, fungi, viruses and archaea that have co-evolved with humans. These microbes have important roles in immune modulation, vitamin synthesis, metabolism etc. The human pharyngeal microbiome, which resides in the junction between digestive and respiratory tracts, might have a key role in the prevention of respiratory tract infections, akin to the actions of the intestinal microbiome against enteric infections. The respiratory tract is constantly exposed to various environmental and endogenous microbes; however, unlike other similar mucosal surfaces, there has been limited investigation of the microbiome of the respiratory tract. HIV infection is associated with alterations in the respiratory microbiome. The aim of this study was to use next-generation sequencing to determine the composition of the oropharyngeal microbiome in a HIV-positive individual. The bacterial composition was determined by illumina sequencing using MiSeq of partial 16S rRNA genes (V3-V4). A total of 3, 57,926 reads were analyzed. Overall, the genera Proteus, Enterococcus, Bacteroides, Prevotella and Clostridium were most prevalent bacterial populations in the oropharynx of an HIV positive patient.

Interactions Between Parasites and the Bacterial Microbiota of Chickens

Except for the important role coccidia have as predisposing factors of necrotic enteritis, the role parasites play in the dynamics of a healthy microbiota of chickens is not well explored. This review describes the interactions of relevant intestinal parasites of chickens with bacteria. Infection with Eimeria spp. favor the growth of Clostridium perfringens and suppress the growth of many other bacteria by increasing viscosity and passage time of the ingesta, and by causing lesions to the intestinal mucosa that improve the availability of nutrients for C. perfringens. Conversely, there are indications that bacteria influence the course of disease after infections with Eimeria spp. Not much is known about intestinal cryptosporidiosis in chickens, but results in mice show that the intestinal microbiota induces some resistance against infection with Cryptosporidium parvum and that the innate immune response triggered by infections with cryptosporidia might have an effect on other intestinal microbes. Histomonas meleagridis depend on bacteria in vitro, and in vivo it will cause lesions in chickens only in the presence of bacteria. Blastocystis spp. are very common in chickens, but there is no information about interactions with bacteria. In humans, there is evidence of the correlation of the detection of Blastocystis and changes in the intestinal microbiota. There are indications of interactions between Ascaridia galli and various bacteria in chickens and Ascaridia spp. of mammals are known to produce various types of antimicrobial molecules. However, often the underlying mechanisms of these interactions between parasites and bacteria remain unknown and only correlations but not causation can be established.

The role of Blastocystis hominis in the activation of ulcerative colitis

BACKGROUND/AIMS

Several studies have shown that a change in microbiota plays an important role in the pathogenesis of inflammatory bowel disease (IBD). Furthermore, with the emergence in recent studies of differences according to the subtype of IBD and whether the disease is active or in remission, there has started to be research into the relationship between IBD and several microorganisms. Blastocystis hominis is primary among these organisms. The aim of the present study was to determine the role of B. hominis in the acute flare-up of ulcerative colitis (UC).

MATERIALS AND METHODS

A total of 114 patients with UC were included in the study, with 52 in the active phase. The Mayo scoring system was used for the activity index. Patients determined with a flare-up agent other than B. hominis were excluded from the study. Fecal samples of the patients were examined by the polymerase chain reaction method for the presence of B. hominis.

RESULTS

B. hominis positivity was determined in 37 (34%) patients with UC. Of the patients, 17 (32.6%) were in the acute flare-up phase, and 20 (32.2%) were in remission (p=0.961). In 11 (64.7%) of the B. hominis positive patients, the disease severity was determined as mild-moderate (p<0.001).

CONCLUSION

The results of the present study showed that while there was no difference between the active and remission phases in respect of B. hominis presence, there was milder involvement in those determined with B. hominis.

Pinning down the role of common luminal intestinal parasitic protists in human health and disease - status and challenges

While some single-celled intestinal parasites are direct causes of diarrhoea and other types of intestinal pathology, the impact of other gut micro-eukaryotes on human health remains elusive. The fact that some common luminal intestinal parasitic protists (CLIPPs) have lately been found more often in healthy than in diseased individuals has fuelled the hypothesis that some parasites might in fact be protective against disease. To this end, the use of new DNA technologies has helped us investigate trans-kingdom relationships in the gut. However, research into these relationships is currently hampered by the limited data available on the genetic diversity within the CLIPPs genera, which results in limited efficacy of publicly available DNA sequence databases for taxonomic annotation of sequences belonging to the eukaryotic component of the gut microbiota. In this paper, I give a brief overview of the status on CLIPPs in human health and disease and challenges related to the mapping of intestinal eukaryotic diversity of the human gut.

Fecal Microbiota Transplantation: Current Status in Treatment of GI and Liver Disease

Fecal microbiota transplantation was originally introduced as a method to repair intestinal microbiota following failure of multiple treatments of recurrent Clostridiumdifficile infection with antibiotics. However, it is hypothesized that intestinal dysbiosis may contribute to the pathogenesis of many diseases, especially those involving the gastrointestinal tract. Therefore, fecal microbiota transplantation is increasingly being explored as a potential treatment that aims to optimize microbiota composition and functionality. Here, we review the current state of fecal microbiota transplantation development and applications in conditions of greatest interest to a gastroenterologist.

Parasites and their (endo)symbiotic microbes

Thanks to modern molecular biology methods, our understanding of the impact of (endo)symbiotic bacteria on parasitic protists and helminths is growing fast. In this issue, 9 papers have been brought together that describe various facets of the relationships between these microorganisms, reveal their range and high frequency, as well as their capacity to create novel biological complexity. Comparative analyses of these host-endosymbiont interactions indicate that there may be no discrete types of relationships but rather a continuum ranging from a dispensable endosymbiont minimally integrated within the host cell to organelles, such as mitochondria and plastids that evolved into an indispensable, deeply integrated components of the cell. We hope that this series of studies on parasites and (endo)symbiotic bacteria will increase awareness about these relationships and their representation in microbial ecology models.

Evaluating rodent experimental models for studies of Blastocystis ST1

Blastocystis is a common inhabitant of the human gut, colonizing at least one billion people at a prevalence ranging from <10% to 100% in healthy human populations globally. The majority of carriers remain asymptomatic, suggesting that Blastocystis is largely a commensal, though Blastocystis has also been implicated in disease in some people. However, there are no in vivo model systems in which to experimentally test the impact of Blastocystis on mammalian hosts and the gut ecosystem and determine which factors underlie these variable clinical outcomes. We evaluated a rat model for sustaining of a human-derived Blastocystis ST1 and assess colonization success and longevity. Because of the broad host range of Blastocystis, we compared the rat with three other rodent species to establish the reproducibility of our method. Blastocystis was introduced by esophageal gavage and colonization success evaluated by Blastocystis culture. Culture was also used to determine that all animals were negative prior to colonization and negative controls remain Blastocystis-free. In this study, Blastocystis ST1 established in 100% of the outbred rats (Rattus norvegicus) and gerbils (Meriones unguiculatus) challenged. Rats were colonized asymptomatically for more than one year, but Blastocystis ST1 was not transmitted between rats. Mus musculus strain CD1 and Mastomys coucha were not susceptible to Blastocystis ST1. Thus, rats appear to be a suitable in vivo model for studies of Blastocystis ST1, as do gerbils though testing was less extensive. This work lays the foundation for experimental work on the role of Blastocystis in health and disease.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

The benign helminth Hymenolepis diminuta ameliorates chemically induced colitis in a rat model system

The tapeworm Hymenolepis diminuta is a model for the impact of helminth colonization on the mammalian immune system and a candidate therapeutic agent for immune mediated inflammatory diseases (IMIDs). In mice, H. diminuta protects against models of inflammatory colitis by inducing a strong type 2 immune response that is activated to expel the immature worm. Rats are the definitive host of H. diminuta, and are colonized stably and over long time periods without harming the host. Rats mount a mild type 2 immune response to H. diminuta colonization, but this response does not generally ameliorate colitis. Here we investigate the ability of different life cycle stages of H. diminuta to protect rats against a model of colitis induced through application of the haptenizing agent dinitrobenzene sulphonic acid (DNBS) directly to the colon, and monitor rat clinical health, systemic inflammation measured by TNFα and IL-1β, and the gut microbiota. We show that immature H. diminuta induces a type 2 response as measured by increased IL-4, IL-13 and IL-10 expression, but does not protect against colitis. In contrast, rats colonized with mature H. diminuta and challenged with severe colitis (two applications of DNBS) have lower inflammation and less severe clinical symptoms. This effect is not related the initial type 2 immune response. The gut microbiota is disrupted during colitis and does not appear to play an overt role in H. diminuta-mediated protection.

Recruitment of feces donors among blood donors: Results from an observational cohort study

As the use of fecal microbiota transplantation (FMT) has gained momentum, an increasing need for continuous access to healthy feces donors has developed. Blood donors constitute a healthy subset of the general population and may serve as an appropriate group for recruitment. In this study, we investigated the suitability of blood donors as feces donors. In a prospective cohort study, we recruited blood donors onsite at a public Danish blood bank. Following their consent, the blood donors underwent a stepwise screening process: First, blood donors completed an electronic pre-screening questionnaire to rule out predisposing risk factors. Second, eligible blood donors had blood and fecal samples examined. Of 155 blood donors asked to participate, 137 (88%) completed the electronic pre-screening questionnaire, 16 declined, and 2 were excluded. Of the 137 donors who completed the questionnaire, 79 (58%) were excluded mainly due to having an allergy, being overweight, or presenting gastrointestinal complaints. Among the remaining 58 (37%) donors, complete blood and feces screenings were obtained from 46 (79%). Of these 46 donors, 15 (33%) were excluded primarily due to abnormal blood results or the presence of apathogenic intestinal parasites. Overall, 31 (20%; 95% confidence interval 14-27%) of the 155 blood donors qualified as feces donors. In conclusion, blood donors constitute a suitable and motivated population for a continuous recruitment of voluntary feces donors. We found that a stepwise recruitment procedure was feasible and that 20% of the blood donors were eligible for feces donation.

The gut microbiota and its potential role in obesity

The human GI tract harbors a diverse and dynamic microbial community comprising bacteria, archaea, viruses and eukaryotic microbes, which varies in composition from individual to individual. A healthy microbiota metabolizes various indigestible dietary components of the host, maintains host immune homeostasis and nutrient intake, but, an imbalanced microbiota has been reported to be associated with many diseases, including obesity. Rodent studies have produced evidence in support of the causal role of the gut microbiota in the development of obesity, however, such causal relationship is lacking in humans. The objective of this review is to critically analyze the vast information available on the composition, function and alterations of the gut microbiota in obesity and explore the future prospects of this research area.

Distribution and phylogenetic analysis of Blastocystis sp. subtypes isolated from IBD patients and healthy individuals in Iran

Blastocystis is a single-celled intestinal parasite commonly found in humans and a broad range of animals all over the world. In humans, its role in health and disease remains unsettled. The aim of our study was to investigate the distribution of Blastocystis and Blastocystis subtypes (ST) in patients with inflammatory bowel disease (IBD) and control subjects. A total of 71 stool samples were collected from IBD patients, 69 and 2 of whom had ulcerative colitis (UC) and Crohn's Disease (CD), respectively. Moreover, 166 stool samples from healthy subjects were included as control samples. All stool samples were cultivated, and 550-bp fragments of the small subunit ribosomal RNA gene was amplified from Blastocystis-positive cultures. All PCR-positive samples were sequenced. Blastocystis was observed in 9 (12.67%) and 35 (21.1%) IBD patients and healthy controls, respectively. There was no statistically significant correlation between IBD and presence of Blastocystis (P = 0.147). There was a statistically significant correlation between age and Blastocystis colonization in the IBD group (P < 0.05), but not among healthy controls. No significant correlation between gender and colonization was observed. ST1 and ST3 were obtained from 1 (12.5%) and 7 (87.5%) IBD patients, respectively, while in the healthy control group, subtypes 1, 2, and 3 were found in 14 (40%), 12 (34.28%), and 9 (25.72%), respectively. Phylogenetic analysis showed no variation in the distribution of subtypes nor intra-subtype genetic diversity between samples acquired from IBD patients and healthy controls. This study showed a trend towards a lower prevalence of Blastocystis in IBD patients than in control subjects. ST3 sequences isolated from IBD patients and control individuals did not appear to differ genetically.

Challenges in fecal donor selection and screening for fecal microbiota transplantation: A review

Fecal microbiota transplantation is best understood as an effective and inexpensive therapy for recurrent Clostridium difficile infection but fecal donor selection and screening should be periodically revised. Here, we review current recommendations for selection and screening of fecal donors for fecal microbiota transplantation. We recommend considering diabetes mellitus, prior cardiovascular events, and clinical healthcare exposure as fecal donor exclusion criteria until more is known about the association of these conditions with the human gut microbiome. We review the non-bacterial members of the human gut microbiome, associations of the gut microbiome with colorectal malignancies, the human gut resistome and how these may impact future donor screening recommendations. Collaboration between clinicians, clinical laboratory scientists, industry and regulatory agencies will be critically important for continued improvement in donor selection and screening.

Blastocystis in ulcerative colitis patients: Genetic diversity and analysis of laboratory findings

OBJECTIVE

To determine Blastocystis frequency and subtypes (ST) in ulcerative colitis (UC) patients and analyse some laboratory findings between Blastocystis positive and negative cases.

METHODS

Faecal samples from 150 UC patients in Adnan Menderes University, Training and Research Hospital were examined by direct microscopy and cultivated in Jones medium. Blastocystis positive cultures were subjected to DNA isolation and subtypes were identified by sequencing of barcode region. A retrospective analysis was conducted on C reactive protein (CRP), leucocyte counts (WBC), neutrophil counts, and sedimentation rates.

RESULTS

The overall positive rate of Blastocystis was 8% (12 patients) and the most abundant subtype was ST3 (eight isolates, 66.7%), followed by ST1, ST2 and ST7. Laboratory findings between Blastocystis infected and non-infected UC patients were not significantly different. Blastocystis frequency was 3.8% among the patients in active stage, while it was 11.8% among the patients in remission stage.

CONCLUSIONS

The present study confirms previous findings that have indicated the predominance of Blastocystis ST3 in humans and contributes additional evidence that suggests the low colonisation of Blastocystis infection in ulcerative colitis patients during active stage.

Associations between common intestinal parasites and bacteria in humans as revealed by qPCR

Several studies have shown associations between groups of intestinal bacterial or specific ratios between bacterial groups and various disease traits. Meanwhile, little is known about interactions and associations between eukaryotic and prokaryotic microorganisms in the human gut. In this work, we set out to investigate potential associations between common single-celled parasites such as Blastocystis spp. and Dientamoeba fragilis and intestinal bacteria. Stool DNA from patients with intestinal symptoms were selected based on being Blastocystis spp.-positive (B+)/negative (B-) and D. fragilis-positive (D+)/negative (D-), and split into four groups of 21 samples (B+ D+, B+ D-, B- D+, and B- D-). Quantitative PCR targeting the six bacterial taxa Bacteroides, Prevotella, the butyrate-producing clostridial clusters IV and XIVa, the mucin-degrading Akkermansia muciniphila, and the indigenous group of Bifidobacterium was subsequently performed, and the relative abundance of these bacteria across the four groups was compared. The relative abundance of Bacteroides in B- D- samples was significantly higher compared with B+ D- and B+ D+ samples (P < 0.05 and P < 0.01, respectively), and this association was even more significant when comparing all parasite-positive samples with parasite-negative samples (P < 0.001). Additionally, our data revealed that a low abundance of Prevotella and a higher abundance of Clostridial cluster XIVa was associated with parasite-negative samples (P < 0.05 and P < 0.01, respectively). Our data support the theory that Blastocystis alone or combined with D. fragilis is associated with gut microbiota characterized by low relative abundances of Bacteroides and Clostridial cluster XIVa and high levels of Prevotella.

Colonization with the enteric protozoa Blastocystis is associated with increased diversity of human gut bacterial microbiota

Alterations in the composition of commensal bacterial populations, a phenomenon known as dysbiosis, are linked to multiple gastrointestinal disorders, such as inflammatory bowel disease and irritable bowel syndrome, or to infections by diverse enteric pathogens. Blastocystis is one of the most common single-celled eukaryotes detected in human faecal samples. However, the clinical significance of this widespread colonization remains unclear, and its pathogenic potential is controversial. To address the issue of Blastocystis pathogenicity, we investigated the impact of colonization by this protist on the composition of the human gut microbiota. For that purpose, we conducted a cross-sectional study including 48 Blastocystis-colonized patients and 48 Blastocystis-free subjects and performed an Ion Torrent 16S rDNA gene sequencing to decipher the Blastocystis-associated gut microbiota. Here, we report a higher bacterial diversity in faecal microbiota of Blastocystis colonized patients, a higher abundance of Clostridia as well as a lower abundance of Enterobacteriaceae. Our results contribute to suggesting that Blastocystis colonization is usually associated with a healthy gut microbiota, rather than with gut dysbiosis generally observed in metabolic or infectious inflammatory diseases of the lower gastrointestinal tract.

The healthy human microbiome

Humans are virtually identical in their genetic makeup, yet the small differences in our DNA give rise to tremendous phenotypic diversity across the human population. By contrast, the metagenome of the human microbiome—the total DNA content of microbes inhabiting our bodies—is quite a bit more variable, with only a third of its constituent genes found in a majority of healthy individuals. Understanding this variability in the “healthy microbiome” has thus been a major challenge in microbiome research, dating back at least to the 1960s, continuing through the Human Microbiome Project and beyond. Cataloguing the necessary and sufficient sets of microbiome features that support health, and the normal ranges of these features in healthy populations, is an essential first step to identifying and correcting microbial configurations that are implicated in disease. Toward this goal, several population-scale studies have documented the ranges and diversity of both taxonomic compositions and functional potentials normally observed in the microbiomes of healthy populations, along with possible driving factors such as geography, diet, and lifestyle. Here, we review several definitions of a ‘healthy microbiome’ that have emerged, the current understanding of the ranges of healthy microbial diversity, and gaps such as the characterization of molecular function and the development of ecological therapies to be addressed in the future.