Distribution and relevance of Dientamoeba fragilis and Blastocystis species in gastroenteritis: results from a case-control study

Improvement of the diagnosis of intestinal protozoa using a multiplex qPCR strategy compared to classical microscopy: a prospective study on 3,500 stool samples over 3 years

Commercial multiplex real-time PCR (qPCR assays) are now widely used for the diagnosis of intestinal protozoan infections, but few prospective studies evaluated their performances on large patient cohorts. We extracted data from our information system from 1 January 2021 to 15 March 2024 and included all stool samples analyzed in routine. Parasites were searched using a multiplex PCR (AllPlex Gastrointestinal Panel assay, Seegene) and microscopic examination with two concentration methods. Acid-fast staining was performed when Cryptosporidium detection was specifically requested. In total, 3,495 stools were analyzed from 2,127 patients. Giardia intestinalis, Cryptosporidium spp., Entamoeba histolytica, Dientamoeba fragilis, and Blastocystis spp. were found by multiplex qPCR in 45 (1.28%), 30 (0.85%), 9 (0.25%), 310 (8.86%), and 673 (19.25%) samples, respectively, alone or in combination (n = 909). In the vast majority of cases, PCR detected a protozoan on the first stool sample. Microscopy was positive for G. intestinalis, Cryptosporidium spp., Entamoeba histolytica/dispar, D. fragilis, and Blastocystis spp. in 25 (0.7%), 8 (0.23%), 24 (0.68%), 22 (0.63%), and 229 (6.55%), samples, respectively, alone or in combination (n = 286 samples). No samples were PCR-/Microscopy+ for G. intestinalis, Cryptosporidium spp., and E. histolytica, while D. fragilis and Blastocystis spp. were detected only with microscopy in 6 and 20 samples, respectively. Microscopy allowed the detection of parasites not targeted by the multiplex panel (5 Cystoisospora belli, 331 samples with non-pathogenic protozoa, and 68 samples with helminths). Overall, the multiplex PCR proved more efficient to detect protozoan parasites, but a microscopic technique should be performed when infection with C. belli (HIV-infected patients) or helminths is suspected (migrants and travelers).IMPORTANCEIn the era of increasing use of multiplex PCR panels for the diagnosis of intestinal protozoan infections, it is important to form an opinion on the positioning of those assays within a lab workflow. This study analyzes routine results obtained prospectively by microscopy and a commercial multiplex PCR over 3 years, and shows that the assay meets the expectations of a clinical laboratory for the detection of protozoan parasites of medical interest. It is recalled that Cystoisospora belli is not targeted by the multiplex assay, and that microscopy still remains necessary to detect helminths.

Dientamoeba fragilis: An emerging pathogen

Dientamoeba fragilis is a protozoan of the gastrointestinal tract, very prevalent in our environment and responsible for diverse clinical symptoms mainly abdominal pain, diarrhoea and eosinophilia, although some infected patients are asymptomatic. Since the first description just a century ago, there are many unanswered questions: its different morphologies and the role of each of them, its actual prevalence, the mode of transmission, its pathogenicity, or the treatment of choice, continue to be source of controversy. Risk factors associated with infection by D. fragilis are: contact with children, residence in a rural area, and co-infection by Enterobius vermicularis. New molecular diagnostic techniques in the form of commercial multi-diagnostic panels are now considered first choice techniques. Paromomycin show higher cure rates, than metronidazole.

Parasite load as a marker of pathogenicity in Dientamoeba fragilis infections

Dientamoeba fragilis is a globally widespread intestinal parasite and one of the most frequent in humans, often leading to primary care consultations. The pathogenic potential of this parasite remains unclear due to limited evidence and contradictory study results. This study investigated the pathogenicity of D fragilis, focusing on the critical knowledge gap regarding the relationship between parasite load and associated symptomatology. A prospective case-control study matched by household unit was conducted, considering individuals with gastrointestinal symptoms and D fragilis in stool as cases, and their asymptomatic household members with D fragilis in stools as controls. D fragilis detection was performed in parallel using light microscopy and real time-polymerase chain reaction. The study was carried out in 7 primary care centers over 12 months. Parasite load was measured as the number of trophozoites per field at a magnification of 40x by microscopy and by cycle threshold values in RT-PCR. A total of 218 individuals were recruited: 74 symptomatic cases and 144 household members, of whom 57 (39.6%) were D fragilis-positive asymptomatic controls. The proportion of individuals with D fragilis and a parasite load less than 1 trophozoite per field was higher in asymptomatic individuals (controls) than in symptomatic cases (47.7% vs 3.1%, respectively) (P < .001). Parasite load is associated with the presence of gastrointestinal symptoms, supporting the pathogenicity of D fragilis. Any diagnostic approach for D fragilis should incorporate or be complemented by quantitative information to accurately estimate parasite load and enhance treatment decision-making.

Genetic diversity and prevalence of Blastocystis subtypes in Alborz Province, Iran: A molecular epidemiological study

The primary objective of this study was to evaluate the genetic diversity of Blastocystis. Additionally, it aimed to explore, for the first time in Iran, the potential association between Blastocystis infection and ABO blood groups. Another focus was to examine the relationship between Blastocystis subtypes and blood groups, an often overlooked risk factor, within the population of Alborz Province, Iran. 450 stool samples were collected from diagnostic facilities across Alborz Province between June 2022 and April 2024. The presence of Blastocystis was confirmed in 64 out of 450 samples (14.22 %) using the Nested PCR-RFLP technique. Among the 64 positive samples, nine (2 %) were classified as indeterminate. Two distinct Blastocystis subtypes were identified in 55 isolates, accounting for 12.22 % of the total samples. ST1 was detected in 44 isolates (9.77 %), rendering it the most prevalent subtype, while ST3 was identified in 11 isolates (2.44 %). Phylogenetic trees were constructed using sequencing data and compared against genotypes available in GenBank. Significant differences between infected and non-infected individuals were observed regarding educational attainment, marital status, and blood type (p < 0.05). A significant association was found between ABO blood groups and the prevalence of Blastocystis infection (p = 0.019). However, when examining the correlation between Blastocystis subtypes (ST1 and ST3) and ABO blood groups, no significant overall association was observed. Nonetheless, specific associations were found for blood groups O+ and B-, with subtype ST1 being more prevalent in these groups.

Diabetes and gut microbiome

Diabetes mellitus represents a significant global health problem. The number of people suffering from this metabolic disease is constantly rising and although the incidence is heterogeneous depending on region, country, economic situation, lifestyle, diet and level of medical care, it is increasing worldwide, especially among youths and children, mainly due to lifestyle and environmental changes. The pathogenesis of the two most common subtypes of diabetes mellitus, type 1 (T1DM) and type 2 (T2DM), is substantially different, so each form is characterized by a different causation, etiology, pathophysiology, presentation, and treatment. Research in recent decades increasingly indicates the potential role of the gut microbiome in the initiation, development, and progression of this disease. Intestinal microbes and their fermentation products have an important impact on host metabolism, immune system, nutrient digestion and absorption, gut barrier integrity and protection against pathogens. This review summarizes the current evidence on the changes in gut microbial populations in both types of diabetes mellitus. Attention is focused on changes in the abundance of specific bacterial groups at different taxonomic levels in humans, and microbiome shift is also assessed in relation to geographic location, age, diet and antidiabetic drug. The causal relationship between gut bacteria and diabetes is still unclear, and future studies applying new methodological approaches to a broader range of microorganisms inhabiting the digestive tract are urgently needed. This would not only provide a better understanding of the role of the gut microbiome in this metabolic disease, but also the use of beneficial bacterial species in the form of probiotics for the treatment of diabetes.

High rates of Dientamoeba fragilis and Blastocystis species in children's stool but minor clinical significance

OBJECTIVE

The aim of this study was to describe the epidemiology and the clinical significance of Dientamoeba fragilis (DF) and Blastocystis (Bs) in pediatric stool samples.

METHODS

A historical cohort study of children under 18 years of age who underwent stool multiplex PCR for bacteria and parasites. DF and Bs results were not routinely reported. We assessed the frequency of various stool microorganisms and analyzed a composite of symptoms occurring within 14 days before testing and four post-test composite outcomes (symptoms, further medical evaluation, prescriptions of symptomatic treatment or antibiotics). Comparisons were made between children mono-infected with DF or Bs, those with negative PCR results, and those positive for microorganisms with established pathogenicity.

RESULTS

Of 36,008 eligible children, 32.5% were positive for DF and 7.9% for Bs. Children positive for DF or Bs did not exhibit higher odds for pre- or post-test composite outcomes compared to those with all-negative PCR results, except for increased rates of abdominal pain and referrals for anti-TTG testing among DF-positive children. Antibiotic prescription was significantly more common among those positive for microorganisms of known pathogenicity.

CONCLUSIONS

While DF and Bs are frequently detected in pediatric stool samples, their clinical significance appears to be limited.

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

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

The epidemiology of intestinal protozoa in the Israeli population based on molecular stool test: a nationwide study

Stool examination using microscopy was the traditional method for the diagnosis of intestinal parasites. Recently, the use of molecular tests to identify stool protozoa has become the main tool used in most clinical laboratories in Israel. This study aimed to evaluate the prevalence of intestinal parasites in Israel and to compare this prevalence in laboratories that use molecular tests vs a laboratory that uses microscopy. Samples collected from January to October 2021 at seven laboratories were analyzed by real-time PCR (RT-PCR) or by microscopy. The multiplex panel included the following pathogens: Giardia lamblia, Entamoeba histolytica, Cryptosporidium spp., Cyclospora, Dientamoeba fragilis, and Blastocystis spp. Overall, 138,415 stool samples were tested by RT-PCR and 6,444 by microscopy. At least one protozoa species was identified in 28.4% of the PCR-tested samples compared to 4.6% of the microscopy-tested samples. D. fragilis was the most common PCR-identified species (29%). D. fragilis, G. lamblia, and Cryptosporidium spp. were mainly found in pediatric population, while Blastocystis spp. was most prevalent among adults (P < 0.001). In a sub-cohort of 21,480 samples, co-infection was found in 4,113 (19.15%) samples, with Blastocystis spp. and D. fragilis being the most common (14.9%) pair. Molecular stool testing proved more sensitive compared to microscopy. D. fragilis was the most commonly detected pathogen. The above profile was identified during the COVID pandemic when traveling was highly restricted and most likely represents the locally circulating protozoa.

IMPORTANCE

This study sheds light on the prevalence of stool parasites in Israel. Additionally, this study indicates that the shift from microscope analysis to molecular tests improved protozoa diagnosis.

Molecular detection and genotyping of Dientamoeba fragilis and Blastocystis sp. in housefly Musca domestica (Diptera: Muscidae): first report for Dientamoeba fragilis

Dientamoeba fragilis and Blastocystis sp. are single-celled protozoan parasites of humans and animals. Although they are found in the intestines of healthy hosts, the pathogenicity of them is still unclear. To date, there is no report on D. fragilis and only two studies (without subtyping) on the occurrence of Blastocystis sp. in Musca domestica. In this study, fly samples were collected from livestock farms and their surroundings in the Kirsehir province (Central Anatolia Region) of Türkiye from May to August 2023. A total of 150 microscopically identified M. domestica samples were analyzed for the detection of D. fragilis and Blastocystis sp. molecularly. The overall prevalence of Blastocystis sp. and D. fragilis in M. domestica was determined to be 3.3% (5/150) and 8.0% (12/150), respectively. The SSU rRNA gene sequences of the isolates indicated genotype 1 of D. fragilis. Eleven isolates were identical and represented a single isolate (KAU-Dfrag1). BLAST analysis of KAU-Dfrag1 indicated identity with the isolates reported from humans, cattle, sheep, and budgerigars. The other isolate (KAU-Dfrag2) was polymorphic at two nucleotides from KAU-Dfrag1 and three nucleotides from known genotypes from GenBank and represented a variant of genotype 1. The Blastocystis sp. isolates were found to be identical and represent a single genotype (KAU-Blast1). BLAST analysis revealed that the KAU-Blast1 genotype belonged to the potentially zoonotic subtype 5 (ST5) and exhibited the highest genetic identity (ranging from 99.4 to 99.6%) with pigs, cattle, and sheep from different countries. Our study provides the first data on the molecular prevalence, epidemiology, and genotypic characterization of D. fragilis and Blastocystis sp. in M. domestica.

Molecular prevalence and subtype distribution of Blastocystis spp. among children who have diarrheia or are asymptomatic in Wenzhou, Zhejiang Province, China

Blastocystis sp., a significant zoonotic parasite with a global distribution, was the focus of this study, which aimed to investigate its prevalence and genetic diversity among diarrheic and asymptomatic children in Wenzhou, China. We collected 1,032 fecal samples from Yuying Children's Hospital, Wenzhou, China, comprising 684 from children with diarrhea and 348 from asymptomatic children. Genomic DNA extracted from these samples was used to detect Blastocystis spp. by PCR, targeting the small subunit ribosomal RNA gene. Subsequently, a phylogenetic tree was constructed, applying the maximum likelihood method. Blastocystis spp. were detected in 67 (6.5%) of the fecal samples. The prevalence rate of Blastocystis spp. in diarrheic children (8.8%; 60/684) was significantly higher than that in asymptomatic children (2.0%; 7/348) (χ 2 = 17.3, p < 0.001). Sequence analysis of the SSU rRNA gene identified five known Blastocystis spp. subtypes, ST1 (n = 12), ST2 (n = 5), ST3 (n = 35), ST4 (n = 12), and ST7 (n = 3). ST1 and ST3 were present in both diarrheic and asymptomatic children, while ST2, ST4, and ST7 were exclusive to diarrheic children. Intra-subtype genetic polymorphisms were identified, comprising four variations in ST1 (ST1-1 to ST1-4), five in ST3 (ST3-1 to ST3-5), two in ST4 (ST4-1 and ST4-2), and two in ST7 (ST7-1 and ST7-2). Notably, ST1-2 to ST1-4, ST3-3 to ST3-5, and ST7-1 and ST7-2 represent newly identified variations. The composition and genetic characteristics of subtypes among children in this region suggest various sources of infection, including human-to-human and animal-to-human transmission.

The clinical significance of Dientamoeba fragilis and Blastocystis in human stool-retrospective cohort study

OBJECTIVES

The aim of this study was to assess the clinical significance of Dientamoeba fragilis (DF) and Blastocystis species (Bs) in human stool.

METHODS

Observational study of patients ≥18 years, who were tested by stool multiplex PCR for bacteria and parasites between April 2019 and March 2022. Although DF and Bs are part of the PCR kit, these results are not routinely reported to the patient or the ordering physician. The main outcomes were the incidence of symptoms during 14 days before the referral to stool PCR test, and the incidence of several clinical outcomes during 60 days after the PCR test (symptoms, referrals to further evaluation, prescription of symptomatic, or antibiotic treatment).

RESULTS

A total of 27 918 patients were tested by stool PCR during the 3 study years. A total of 6215 (22.3%) and 5337 (19.2%) were positive for DF and Bs, respectively. The incidence of symptoms before the test was similar in those positive for Bs or DF and those with all-negative PCR (adjusted OR and 95% CI of 0.87 [0.80-0.95] and 0.82 [0.76-0.88] for Bs and DF, respectively), whereas significantly higher (2.47 [2.23-2.73]) in those positive for the other multiplex PCR assay components. During the 60 days after the test, the prevalence of any of the outcomes was similar in those positive for Bs or DF and those with negative PCR (adjusted OR and 95% CI of 0.92 [0.83-1.02] and 0.89 [0.81-0.97] for symptoms, 0.84 [0.75-0.94] and 0.93 [0.85-1.01] for referrals, 0.88 [0.75-1.03] and 0.82 [0.71-0.94] for symptomatic treatment, and 0.88 [0.75-1.02] and 0.86 [0.75-0.98] for antibiotic treatment in the Bs and DF positive individuals, respectively). The PCR cycle threshold was not associated with any of the outcomes.

DISCUSSION

Positive stool PCR for DF or Bs was not associated with any of the measured clinical outcomes.

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.

Treatment of Dientamoeba fragilis: A retrospective Finnish analysis of faecal clearance and clinical cure comparing four antiprotozoal drugs

Background

Dientamoeba fragilis (DF), the most common intestinal protozoal pathogen in affluent countries, causes asymptomatic or symptomatic infections with severity ranging from mild to disabling. Currently, many studies of treatment options only have small sample sizes and report results that are partly contradictory.

Methods

Investigating data retrieved from Helsinki University Hospital and Helsinki City patient records, we searched for the most effective antiprotozoal in treating DF infections. To study microbiological clearance of DF, we collected laboratory results of control samples from patients given one of four commonly used antiprotozoals: doxycycline, metronidazole, paromomycin, or secnidazole. For patients symptomatic prior to antiprotozoal treatment, we also retrieved data on clinical outcomes. Furthermore, we explored factors associated with faecal clearance and clinical cure.

Results

A total of 369 patients (median age 38) and 492 treatment episodes were included. Paromomycin (n ​= ​297) proved effective (clearance rate 83%), showing strong association with faecal clearance (aOR 18.08 [7.24-45.16], p ​< ​0.001). For metronidazole the rate was 42% (n ​= ​84), for secnidazole 37% (n ​= ​79), and doxycycline 22% (n ​= ​32). In pairwise comparisons, paromomycin outdid the three other regimens (p ​< ​0.001, χ2 test). Faecal clearance was associated with clinical cure (aOR 5.85 [3.02-11.32], p ​< ​0.001).

Conclusions

Faecal clearance, strongly associated with clinical cure, is most effectively achieved with a course of paromomycin, followed by metronidazole, secnidazole and doxycycline. Our findings will be useful in devising treatment guidelines for adults with symptomatic D. fragilis infection.

Evaluation of the Performance of the Novodiag® Stool Parasites Assay for the Detection of Intestinal Protozoa and Microsporidia

OBJECTIVES

We aimed to assess the performance of the Novodiag^® Stool Parasites (NSP) assay in the diagnosis of the most common intestinal protozoan and microsporidia infections.

METHODS

A panel of 167 selected stool samples was retrospectively analysed with the NSP assay and compared to routine microscopy and qPCR methods for the detection of pathogenic protozoa and microsporidia.

RESULTS

Whereas specificity was high for all protozoa and microsporidia, NSP sensitivity was strongly dependent on the comparative method used as reference. When compared to microscopic methods, NSP sensitivity was high (96.7 to 100%) for Blastocystis hominis, Entamoeba histolytica and Cyclospora cayetanensis but was lower for Giardia intestinalis (85.2%) and ≤50% for Cystoisospora belli and Dientamoeba fragilis. In comparison to conventional qPCR, the NSP assay demonstrated lower sensitivity characteristics dependent on parasite loads, reaching 60 to 70% for G. intestinalis, D. fragilis, Cryptosporidium spp. and E. histolytica. Sensitivity was 100% for Enterocytozoon bieneusi, but none of the five samples containing Encephalitozoon spp. were detected.

CONCLUSIONS

The overall performance of the NSP assay in the diagnosis of gastrointestinal protozoa and microsporidia seems to be better than or equivalent to that observed with microscopic methods but inferior to that obtainable with classical targeted qPCR.

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.

A Cross-Sectional Study on the Occurrence of the Intestinal Protist, Dientamoeba fragilis, in the Gut-Healthy Volunteers and Their Animals

Dientamoeba fragilis is a cosmopolitan intestinal protist colonizing the human gut with varying prevalence depending on the cohort studied and the diagnostic methods used. Its role in human health remains unclear mainly due to the very sporadic number of cross-sectional studies in gut-healthy populations. The main objective of this study was to expand knowledge of the epidemiology of D. fragilis in gut-healthy humans and their animals. A total of 296 stool samples from humans and 135 samples from 18 animal species were analyzed. Using qPCR, a prevalence of 24% was found in humans in contrast to conventional PCR (7%). In humans, several factors were found to influence the prevalence of D. fragilis. A more frequent occurrence of D. fragilis was associated with living in a village, traveling outside Europe and contact with farm animals. In addition, co-infection with Blastocystis spp. was observed in nearly half of the colonized humans. In animals, D. fragilis was detected in 13% of samples from eight species using qPCR. Our molecular phylogenies demonstrate a more frequent occurrence of Genotype 1 in gut-healthy humans and also revealed a likely a new protist species/lineage in rabbits related to D. fragilis and other related organisms.

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.

Diagnostic and Therapeutic Considerations Towards Dientamoeba fragilis in Children: A Survey Amongst General Practitioners and Pediatricians in the Netherlands

ABSTRACT

This survey was undertaken to obtain insight in the attitude of Dutch physicians towards pathogenicity, diagnostic- and therapeutic approach towards Dientamoeba fragilis in children. Physicians were invited by e-mail for a questionnaire. A total of 211 of 450 physicians (46.9%) completed the questionnaire, including 67 general practitioners (GPs) and 144 pediatricians. Of all respondents, 175 of 211 (82.9%) considered D fragilis a "potential pathogen", when other causes of gastro-intestinal complaints are ruled out. Only 16 of 211 (7.6%) performed diagnostic tests regularly. Diagnostic tests were performed by 162 of 211 (77%) of respondents in children with diarrhea and abdominal pain in consideration of duration of symptoms. Fecal polymerase chain reaction (PCR) was diagnostic modality of preference. Eighty-nine of 142 (62.7%) prescribed metronidazole as antibiotic of first choice. This study shows heterogeneity in clinical practice amongst Dutch physicians regarding diagnostic- and therapeutic approach of D fragilis in children. Different attitude towards pathogenicity and inconsistent guidelines could be causative factors.

From a case-control survey to a diagnostic viral gastroenteritis panel for testing of general practitioners' patients

OBJECTIVE

To evaluate the pathogenicity of a broad range of 11 possible gastroenteritis viruses, by means of statistical relationships with cases vs. controls, or Ct-values, in order to establish the most appropriate diagnostic panel for our general practitioner (GP) patients in the Netherlands (2010-2012).

METHODS

Archived stool samples from 1340 cases and 1100 controls were retested using internally controlled multiplex real-time PCRs for putative pathogenic gastroenteritis viruses: adenovirus, astrovirus, bocavirus, enterovirus, norovirus GI and GII, human parechovirus, rotavirus, salivirus, sapovirus, and torovirus.

RESULTS

The prevalence of any virus in symptomatic cases and asymptomatic controls was 16.6% (223/1340) and 10.2% (112/1100), respectively. Prevalence of astrovirus (adjusted odds ratio (aOR) 10.37; 95% confidence interval (CI) 1.34-80.06) and norovirus GII (aOR 3.10; CI 1.62-5.92) was significantly higher in cases versus controls. Rotavirus was encountered only in cases. We did not find torovirus and there was no statistically significant relationship with cases for salivirus (aOR 1,67; (CI) 0.43-6.54)), adenovirus non-group F (aOR 1.20; CI 0.75-1.91), bocavirus (aOR 0.85; CI 0.05-13.64), enterovirus (aOR 0.83; CI 0.50-1.37), human parechovirus (aOR 1.61; CI 0.54-4.77) and sapovirus (aOR 1.15; CI 0.67-1.98). Though adenovirus group F (aOR 6.37; CI 0.80-50.92) and norovirus GI (aOR 2.22, CI: 0.79-6.23) are known enteropathogenic viruses and were more prevalent in cases than in controls, this did not reach significance in this study. The Ct value did not discriminate between carriage and disease in PCR-positive subjects.

CONCLUSIONS

In our population, diagnostic gastroenteritis tests should screen for adenovirus group F, astrovirus, noroviruses GI and GII, and rotavirus. Case-control studies as ours are lacking and should also be carried out in populations from other epidemiological backgrounds.

Investigation of neglected protists Blastocystis sp. and Dientamoeba fragilis in immunocompetent and immunodeficient diarrheal patients using both conventional and molecular methods

Introduction

The clinical significance of Blastocystis sp. and Dientamoeba fragilis in patients with gastrointestinal symptoms is a controversial issue. Since the pathogenicity of these protists has not been fully elucidated, testing for these organisms is not routinely pursued by most laboratories and clinicians. Thus, the prevalence of these organisms and the subtypes of Blastocystis sp. in human patients in Turkey are not well characterized. This study aimed to determine the prevalence of Blastocystis sp. and D. fragilis in the diarrheic stool samples of immunodeficient and immunocompetent patients using conventional and molecular methods and to identify Blastocystis sp. subtypes using next generation sequencing.

Material and methods

Individual stool specimens were collected from 245 immunodeficient and 193 immunocompetent diarrheic patients between March 2017 and December 2019 at the Gazi University Training and Research Hospital in Ankara, Turkey. Samples were screened for Blastocystis sp. and D. fragilis by conventional and molecular methods. Molecular detection of both protists was achieved by separate qPCRs targeting a partial fragment of the SSU rRNA gene. Next generation sequencing was used to identify Blastocystis sp. subtypes.

Results

The prevalence of Blastocystis sp. and D. fragilis was 16.7% and 11.9%, respectively as measured by qPCR. The prevalence of Blastocystis sp. and D. fragilis was lower in immunodeficient patients (12.7% and 10.6%, respectively) compared to immunocompetent patients (21.8% and 13.5%, respectively). Five Blastocystis sp. subtypes were identified and the following subtype distribution was observed: ST3 54.4% (n = 37), ST2 16.2% (n = 11), ST1 4.4% (n = 3), ST6 2.9% (n = 2), ST4 1.5% (n = 1), ST2/ST3 11.8% (n = 8) and ST1/ST3 8.8% (n = 6). There was no statistically significant difference in the distribution of Blastocystis sp. subtypes between immunocompetent and immunodeficient patients.

Conclusion and recommendation

Our findings demonstrated that Blastocystis sp. and D. fragilis are commonly present in immunocompetent and immunodeficient patients with diarrhea. This study is the first to use next generation sequencing to address the presence of Blastocystis sp. mixed subtypes and intra-subtype variability in clinical samples in Turkey.

Blastocystis sp. and Dientamoeba fragilis are single-cell parasites of the human intestine which are common worldwide and reported in cases with gastrointestinal symptoms. However, the role of Blastocystis sp. and D. fragilis in patients with gastrointestinal symptoms is still controversial because their presence is not always associated with symptoms. As some intestinal parasitic infections can cause severe illness in immunocompromised individuals careful consideration of intestinal protist infection is warranted. However, testing for Blastocystis sp. and D. fragilis is not routinely carried out by most laboratories and clinicians. Therefore, this study aimed to determine the prevalence of Blastocystis sp. and D. fragilis in immunocompetent and immunosuppressed patients with diarrhea by conventional and molecular methods. Both Blastocystis sp. and D. fragilis were detected more frequently by quantitative polymerase chain reaction than by conventional methods. Next generation sequencing was used to characterize the diversity and frequency of Blastocystis sp. subtypes and mixed subtypes in patients in Turkey. Five Blastocystis sp. subtypes (ST1, ST2, ST3, ST4 and ST6) were detected. ST3 was the most frequent subtype in both immunocompetent and immunosuppressed patients. Mono-infections were more common than mixed subtype infections. Our findings showed that Blastocystis sp. and D. fragilis are commonly present in immunocompetent and immunodeficient patients with diarrhea.

Comparative molecular prevalence and subtypes distribution of Blastocystis sp. a potentially zoonotic infection isolated from symptomatic and asymptomatic patients in Iran: A systematic review and meta-analysis

PURPOSE

The present systematic review and meta-analysis was aimed to assess the weighted molecular prevalence of Blastocystis sp. in humans along with the comparative molecular prevalence and subtypes distribution of Blastocystis isolated from symptomatic and asymptomatic patients in Iran.

METHODS

International electronic databases including Medline/PubMed, ProQuest, Scopus, Embase, and Google Scholar were explored until 4th October 2020. Heterogeneity index was evaluated among studies using Cochran's Q test and I² index. Finally, 23 eligible studies were qualified to be included in this review.

RESULTS

The pooled molecular prevalence of Blastocystis sp. in Iran was reported 15.2% (95% CI 11.5-19.7). In addition, the molecular prevalence based on PCR-sequencing and STS primers was reported 12.5% (95% CI 8.6-17.7) and 19.8% (95% CI 13.1-28.8), respectively. Interestingly, there was a considerably higher prevalence among asymptomatic patients [25.1% (95% CI 20.8-30.0)] in comparison to symptomatic ones [21.0% (95% CI 15.9-27.2)]. In addition, the frequency of Blastocystis ST1, ST2, and ST3 from positive samples in symptomatic patients was 19.7%, 35.1%, and 47.4%, respectively. In addition, the prevalence of Blastocystis ST1, ST2, and ST3 from positive samples in asymptomatic patients was 27.1%, 26.8%, and 37.8%, respectively. The results obtained in Iran showed that Blastocystis is more common in asymptomatic patients compared to patients having clinical symptoms. Of note, ST3, as the most common subtype causing clinical symptoms, was the most prevalent reported subtype among both symptomatic and asymptomatic patients in the country.

CONCLUSIONS

Hence, the pathogenicity of the Blastocystis parasite is not subtype-specific and appears to be related to a variety of risk factors. Still the Blastocystis epidemiology is open to question and more large-scale studies should be performed on this aspect.

Impact of Metronidazole Treatment and Dientamoeba Fragilis Colonization on Gut Microbiota Diversity

OBJECTIVES

The intestinal parasite Dientamoeba fragilis is a common colonizer of children in Denmark. Metronidazole has been used to reduce gastrointestinal symptoms in children colonized with D fragilis. We aimed to identify gut microbiota changes associated with D fragilis carrier status and metronidazole treatment of D fragilis-positive children.

METHODS

The fecal microbiota of 275 fecal samples from children treated with metronidazole (n = 48) or placebo (n = 48) were characterized by ribosomal DNA sequencing. Samples collected before (T1), 2 weeks after (T2), and 8 weeks (T5) after treatment were included. Seventy fecal samples from 70 age-matched parasite-negative children served as controls.

RESULTS

The abundance of 24 bacterial genera differed significantly according to D fragilis carrier status, with Flavonifractor being remarkably more abundant in children testing negative for D fragilis. Eight bacterial genera changed significantly in abundance in children losing versus keeping D fragilis after metronidazole treatment. Of these, 7 returned to pretreatment (T1) levels at T5. Meanwhile, the abundance of Flavonifractor continued to differ at T5, whereas for Ruminococcus the abundance only remained high in children who were D fragilis-negative at T2 and T5. Increases in Hungatella, Sutterella, and Streptococcus abundances observed at T2 were specific to metronidazole exposure and hence independent of D fragilis colonization.

CONCLUSIONS

This study revealed that specific bacterial genera were associated with D fragilis colonization. Metronidazole treatment had a short-term impact on the abundance of some bacterial genera, with most of these reverting to pretreatment levels 8 weeks after completed treatment.

Epidemiology and clinical features of intestinal protozoan infections detected by Real-time PCR in non-native children within an Italian tertiary care children's hospital: A cross-sectional study

BACKGROUND

Enteric parasite infections are underestimated due to the limited sensitivity and specificity of microscopy, which remains the diagnostic gold standard in routine clinical practice. This could be a major problem in high-income countries, where the burden of parasitic diseases is low. In recent years, Multiplex Real-Time polymerase chain reaction (RT-PCR) based methods have been implemented. Therefore, the aim of this study was to evaluate the prevalence of four enteric protozoan species detected by RT-PCR in non-native children in Italy, and to describe their clinical characteristics.

METHODS

Adopted and immigrant children, evaluated for migration health assessment between 2017 and 2020 in a tertiary care children's hospital in Italy, were enrolled. Molecular analysis for Giardia lamblia, Dientamoeba fragilis, Blastocystis hominis, and Entamoeba histolytica, was conducted by in-house RT-PCR.

RESULTS

Overall, 209 children were enrolled and 70% of them resulted positive by RT-PCR for at least one enteric parasite. B. hominis (47.8%) was the most commonly identified protozoa, followed by D. fragilis (44.5%). Co-infections with multiple pathogens were detected in 35.4% of the samples. Almost 80% of parasite-positive children were asymptomatic and the most common symptom was flatulence (60.7% of symptomatic children). Eosinophils were significantly increased in RT-PCR positive children compared to the negative ones and children with D. fragilis presented the highest eosinophils count.

CONCLUSIONS

The In-house Multiplex RT-PCR assay provides a valid molecular detection system for selected enteric parasites. This novel and accurate diagnostic method can help in increasing the detection rate of parasite infection, especially in high-risk population.

Diagnosis of intestinal protozoan infections in patients in Cuba by microscopy and molecular methods: advantages and disadvantages

Microscopy is the gold standard for diagnosis of intestinal parasitic diseases in many countries, including Cuba, although molecular approaches often have higher sensitivity as well as other advantages. Fecal samples from 133 patients were analyzed by light microscopy and also real-time multiplex qPCR targeting Giardia duodenalis, Cryptosporidium spp., and Entamoeba histolytica, and, separately, Dientamoeba fragilis. Microscopy revealed G. duodenalis occurred most commonly (17 patients), followed by Blastocystis spp. (12 patients). In a few patients, Entamoeba histolytica/E. dispar, Cryptosporidium spp., and Cyclospora cayetanensis were identified. Molecular analysis identified 4 more G. duodenalis infections and 2 more Cryptosporidium spp. infections; concordance between microscopy and PCR showed almost perfect agreement for G. duodenalis (κ = 0.88) and substantial agreement for Cryptosporidium (κ = 0.74). PCR indicated that E. dispar, rather than E. histolytica, had been identified by microscopy. Additionally, 16 D. fragilis infections were detected using molecular methods. Although both microscopy and molecular techniques have a place in parasitology diagnostics, for parasites such as D. fragilis, where microscopy can underestimate occurrence, molecular techniques may be preferable, and also essential for distinguishing between morphologically similar microorganisms such as E. histolytica and E. dispar. Although in resource-constrained countries such as Cuba, microscopy is extremely important as a diagnostic tool for intestinal parasites, inclusion of molecular techniques could be invaluable for selected protozoa.

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.