Simultaneous detection of less frequent waterborne parasitic protozoa in reused wastewater using amplicon sequencing and qPCR techniques

Waterborne parasitic protozoa (WPP) infections have a worldwide distribution and are a source for epidemic and endemic human diseases. Although a variety of protozoa are commonly detected in wastewater and cited as causative agents of outbreaks, effluents from wastewater treatment plants (WWTPs) used for irrigation can contain other pathogenic protozoa that are not currently being controlled. The lack of control on a routine basis using rapid and sensitive methods to detect these parasites in water may keep them under-recognized. This study focused on using molecular tools, 18 S rRNA amplicon-based sequencing and qPCR, to characterize WPP distribution in wastewater samples from urban WWTPs used for irrigation. A total of eight wastewater samples (from secondary and tertiary disinfection treatment effluents) were collected. Potentially pathogenic protozoa identified by 18 S rRNA sequencing and/or qPCR in the analyzed samples included Acanthamoeba spp., Blastocystis sp., Entamoeba coli, Entamoeba dispar, Entamoeba hartmanni, Giardia intestinalis assemblage A and Toxoplasma gondii Positive results by qPCR were in non-quantifiable levels. Blastocystis sp. was the most represented protozoa among the sequences retrieved from the amplicon sequencing. Blastocystis ST1 and ST2 were the most abundant subtypes among the obtained OTUs. Moreover, Blastocystis sp. ST3, ST4, ST6 and ST8 were also detected, although in lower abundances. Results of this study showed that WWTP effluents used for irrigation can provide a source of WPP.

Evaluation of association with subtypes and alleles of Blastocystis with chronic spontaneous urticaria

Blastocystis is a single-celled parasite commonly found in humans and its pathogenic role is still controversial. In recent years, some studies have suggested that Blastocystis may be a possible agent of gastrointestinal and dermatological symptoms such as acute or chronic urticaria, angioedema, rash, itch, palmoplantar, and diffuse pruritus. We aimed to investigate whether there is a relationship between Blastocystis subtypes and alleles in patients with chronic spontaneous urticaria (CSU) as a case-control study. In this study, stool samples were collected from patients with CSU (n=135) and healthy individuals (n=54). The presence of Blastocystis was investigated using the direct saline smear, Lugol's iodine staining, trichrome staining, Jones' medium culture and PCR assays in stool samples and subtypes (STs) were determined by sequencing according to DNA barcoding. The presence of Blastocystis was identified in 30.4% (64/210) the stool samples, including 31.9% (43/135) of the patients with CSU and 14.8% (8/54) of the control group. Moreover, it was found statistically significant the presence of Blastocystis in terms of both groups (p<0.018). ST3 was detected in 45.9% and 62.5 % as the most prevalent subtype the patients with CSU and the control group, respectively. ST1 (18.9%), ST2 (27%) and ST7 (8.1%) was identified in the patients with CSU group. There was no statistically significant correlation between Blastocystis subtypes and both the groups (p<0.240, p<0.323). Allele 4 for ST1; alleles 9, 10, 11 and 12 for ST2; alleles 34, 36 and 38 for ST3; alleles 41 and 101 for ST7 were detected. Allele 34 (ST3) was found significant in the patients with CSU as compared with control group (p<0.020). Moreover, statistically significant association was found between total IgE value and the certain subtypes (ST2 and ST3) (p<0.0001). As a result of this study, the presence of Blastocystis ST3 allele 34 significantly associated with chronic spontaneous urticaria was revealed.

Prevalence, subtypes and risk factors of Blastocystis spp. infection among pre- and perimenopausal women

Background

Blastocystis spp. are considered pathogenic or commensal organisms, although the majority of researchers suggest that these are neglected pathogens. The main aim of this study was to determine the prevalence and subtype distribution of Blastocystis spp. in pre- and perimenopausal women, with respect to socio-demographic (age and place of residence), and epidemiological factors, as well as drinking tap water, contact with domestic animals, traveling abroad, health status, and presence of gastrointestinal symptoms. Additionally, the objective was to compare hematological and biochemical parameters of Blastocystis spp. infected and uninfected women.

Methods

The study included 425 women aged 45–60. Their stool samples were examined microscopically and analyzed by a conventional polymerase chain reaction (cPCR).

Results

Blastocystis spp. were detected in 6.1% of pre- and perimenopausal women. Molecular analysis of the stool samples identified seven Blastocystis subtypes (ST1–ST4, ST6, ST7, and ST9). Blastocystis subtypes 2 and 3 were the most prevalent. The presence of Blastocystis spp. was not significantly related to socio-demographic and epidemiological factors. There were also no significant associations between Blastocystis spp. and blood parameters, or gastrointestinal symptoms.

Conclusion

This study complements the limited available data on the prevalence of Blastocystis spp. in pre- and perimenopausal women. It is also the first report showing the presence of Blastocystis subtype 9 in Poland.

In vitro susceptibility of human Blastocystis subtypes to simeprevir

Introduction and aim

Blastocystis is a common enteric parasite, having a worldwide distribution. Many antimicrobial agents are effective against it, yet side effects and drug resistance have been reported. Thus, ongoing trials are being conducted for exploring anti-Blastocystis alternatives. Proteases are attractive anti-protozoal drug targets, having documented roles in Blastocystis. Serine proteases are present in both hepatitis C virus and Blastocystis. Since drug repositioning is quite trendy, the in vitro efficacy of simeprevir (SMV), an anti-hepatitis serine protease inhibitor, against Blastocystis was investigated in the current study.

Methods

Stool samples were collected from patients, Alexandria, Egypt. Concentrated stools were screened using direct smears, trichrome, and modified Ziehl-Neelsen stains to exclude parasitic co-infections. Positive stool isolates were cultivated, molecularly subtyped for assessing the efficacy of three SMV doses (100,150, and 200 μg/ml) along 72 hours (h), on the most common subtype, through monitoring parasite growth, viability, re-culture, and also via ultrastructure verification. The most efficient dose and duration were later tested on other subtypes.

Results

Results revealed that Blastocystis was detected in 54.17% of examined samples. Molecularly, ST3 predominated (62%), followed by ST1 (8.6%) and ST2 (3.4%). Ascending concentrations of SMV progressively inhibited growth, viability, and re-culture of treated Blastocystis, with a non-statistically significant difference when compared to the therapeutic control metronidazole (MTZ). The most efficient dose and duration against ST3 was 150 µg/ml for 72 h. This dose inhibited the growth of ST3, ST1, and ST2 with percentages of 95.19%, 94.83%, and 94.74%, successively and viability with percentages of 98.30%, 98.09%, and 97.96%, successively. This dose abolished Blastocystis upon re-culturing. Ultra-structurally, SMV induced rupture of Blastocystis cell membrane leading to necrotic death, versus the reported apoptotic death caused by MTZ. In conclusion, 150 µg/ml SMV for 72 h proved its efficacy against ST1, ST2, and ST3 Blastocystis, thus sparing the need for pre-treatment molecular subtyping in developing countries.

Blastocystis infection frequency and subtype distribution in university students

Blastocystis is a parasite commonly found in the gut of humans and animals; there are 22 known subtypes (STs). STs 1-9 and 12 have been found in humans. This parasite has a faecal-oral route of transmission; its high infection prevalence in developing countries is due to poor hygiene practices, exposure to infected animals, and intake of contaminated water or food. Its pathogenicity has not been established, because it has been found in symptomatic and asymptomatic patients. The goal of this study was to analyze the frequency of Blastocystis and its subtypes (1, 2, 3, 4, 5, and 7), and assess the relationship between these subtypes and abdominal pain and distension. 202 university students participated in this study. A questionnaire was applied to assess the gastrointestinal symptoms, and subsequently the students were asked to provide faecal samples. The presence of parasites was determined by optical microscopy. Blastocystis-positive samples had their DNA extracted and end-point PCR was performed to corroborate the presence of Blastocystis and determine its subtypes. Among the samples, 47.03% were positive according to PCR analysis. The most prevalent subtypes were ST3 (29.79%), ST4 (16.84%), and ST1 (14.89%). We found a relationship between ST1 and abdominal pain (OR = 0.196; CI = 0.0533-0.7318; p = 0.015), and between ST4 and abdominal distension (OR = 0.2928; CI = 0.1017-0.8429; p = 0.023). However, the presence of this parasite and the probable relationship with gastrointestinal symptoms suggest the need to determine its role within intestinal microbiota in order to confirm whether its eradication is really necessary or not.

An Unusual Case of Extra-Enteric Blastocystosis in the Uterine Cervix

Extra-enteric infections by Blastocystis spp. have rarely been documented. Here, we report a case of extra-enteric blastocystosis in a patient with minimal cervicitis symptoms. A 47-year-old Hispanic female patient was attended in a primary health centre in Michoacan state, Mexico, for her routine gynaecological medical examination. As only symptom, she referred to a slight vaginal itching. The presence of several vacuolar-stages of Blastocystis spp. were identified by Papanicolaou staining; molecular identification was attempted by culture-PCR sequencing of a region of 18S gene from cervical and faecal samples obtained 2 months after cytological examination, even when patient declared that she tried self-medicating with vaginal ovules. Blastocystis ST1 was identified only in the faecal sample. The presence of Blastocystis spp. in the cervix of a patient with scarce symptomatology, demonstrates the extraordinary flexibility of this microorganism to adapt to new environments and niches.

Can the pyruvate: ferredoxin oxidoreductase (PFOR) gene be used as an additional marker to discriminate among Blastocystis strains or subtypes?

BACKGROUND

Blastocystis spp. are the most prevalent intestinal eukaryotes identified in humans, with at least 17 genetic subtypes (ST) based on genes coding for the small-subunit ribosomal RNA (18S). It has been argued that the 18S gene should not be the marker of choice to discriminate between STs of these strains because this marker exhibits high intra-genomic polymorphism. By contrast, pyruvate:ferredoxin oxidoreductase (PFOR) is a relevant enzyme involved in the core energy metabolism of many anaerobic microorganisms such as Blastocystis, which, in other protozoa, shows more polymorphisms than the 18S gene and thus may offer finer discrimination when trying to identify Blastocystis ST. Therefore, the objective of the present study was to assess the suitability of the PFOR gene as an additional marker to discriminate among Blastocystis strains or subtypes from symptomatic carrier children.

METHODS

Faecal samples from 192 children with gastrointestinal symptoms from the State of Mexico were submitted for coprological study. Twenty-one of these samples were positive only for Blastocystis spp.; these samples were analysed by PCR sequencing of regions of the 18S and PFOR genes. The amplicons were purified and sequenced; afterwards, both markers were assessed for genetic diversity.

RESULTS

The 18S analysis showed the following frequencies of Blastocystis subtypes: ST3 = 43%; ST1 = 38%; ST2 = 14%; and ST7 = 5%. Additionally, using subtype-specific primer sets, two samples showed mixed Blastocystis ST1 and ST2 infection. For PFOR, Bayesian inference revealed the presence of three clades (I-III); two of them grouped different ST samples, and one grouped six samples of ST3 (III). Nucleotide diversity (π) and haplotype polymorphism (θ) for the 18S analysis were similar for ST1 and ST2 (π = ~0.025 and θ = ~0.036); remarkably, ST3 showed almost 10-fold lower values. For PFOR, a similar trend was found: clade I and II had π = ~0.05 and θ = ~0.05, whereas for clade III, the values were almost 6-fold lower.

CONCLUSIONS

Although the fragment of the PFOR gene analysed in the present study did not allow discrimination between Blastocystis STs, this marker grouped the samples in three clades with strengthened support, suggesting that PFOR may be under different selective pressures and evolutionary histories than the 18S gene. Interestingly, the ST3 sequences showed lower variability with probable purifying selection in both markers, meaning that evolutionary forces drive differential processes among Blastocystis STs.

Blastocystis and urticaria: Examination of subtypes and morphotypes in an unusual clinical manifestation

Blastocystis is a human common enteric protist that may colonize a large variety of non-human hosts linked to symptoms and diseases such as abdominal pain, constipation, diarrhea, urticaria, flatulence and irritable bowel syndrome (IBS). Blastocystis exhibits remarkable genetic diversity and multiple subtypes (STs) within the genus with no absolute associations with clinical symptomatology. Here we analyzed fecal samples from Argentinean patients (n=270) belonging to symptomatic (urticaria and non-specific gastrointestinal symptoms, n=39) and asymptomatic control (n=28). Those patients infected with Blastocystis (n=67) were submitted for morphological analysis, DNA extraction, 18S PCR, sequencing and STs identification according to DNA barcoding. Blastocystis vacuolar forms were the predominant morphotype (75%), ameboid-like forms were evidenced in 1.5% of samples. Blastocystis ST3 was detected in 71.6% (n=48), of which 71.4%, (n=35) and 28.6% (n=14) belonged to symptomatic and asymptomatic respectively. Other subtypes identified were ST1 (14.9%), ST6 (7.5%) and ST2 (5.9%). Blastocystis 18S barcoding evidenced in non-urticaria symptomatic patients and asymptomatic control group the presence of allele 134 (ST3) (p<0.0001), while allele 34 (ST3) was detected in 85.7% (18/21) of symptomatic uricaria as compared with control group (1/21) (p<0.0001). The presence of a particular allele (a34) significantly associated with urticaria patients was detected and the clinical implications of these findings are herein discussed.

Molecular epidemiology and genetic diversity of Blastocystis infection in humans in Italy

In order to describe the molecular epidemiology of Blastocystis infection in Italy, 189 isolates, which had been collected during the years 2012-2014 from mildly symptomatic patients, or those affected by inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) or chronic diarrhoea, or otherwise immunosuppressed, were subtyped by sequence analysis of the SSU rRNA gene (536 bp). Six subtypes (STs) were detected: ST1 (15·3%), ST2 (13·8%), ST3 (46·0%), ST4 (21·7%), ST6 (3·2%) and ST8 (0·5%). They clustered in distinct clades, as inferred from Bayesian inference phylogenetic and median joining network analyses. A high genetic differentiation was found at the inter-subtype level; it ranged from Jukes-Cantor (JC) distance = 0·02 (between ST1 and ST4) to JC = 0·11 (between ST6 and ST2). At the intra-ST level, a high genetic homogeneity was registered in ST4, whereas higher genetic variation was found in isolates corresponding to ST1 and ST2. Accordingly, high values of haplotype and nucleotide diversity were observed in ST1, ST2 and ST3. No association was found between patient gender and ST, whereas ST3 and ST1 were significantly more prevalent in patients aged 15-50 years. A significant occurrence of Blastocystis ST4 in patients suffering from IBS, IBD or chronic diarrhoea was observed; in addition, a slight significant association between ST1 and ST3 and IBS patients was found. Multiple correspondence analysis showed some significant contribution of different variables (subtypes, haplotypes, age) in the observed pattern of ordination of the 189 patients in the symptom categories.