Blastocystis hominis as a cause of hypoalbuminemia and anasarca

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.

Blastocystis spp. and Giardia intestinalis co-infection profile in children suffering from acute diarrhea

Giardia intestinalis and Blastocystis spp. are two common zoonotic intestinal parasites responsible for the majority of diarrheic cases, especially in children. The study was planned to determine the impact role of both Giardia and Blastocystis co-infection in children up to 12 years old with acute diarrhea in Beni-Suef, Egypt. Also, to estimate the general prevalence rates and risk factors associated with intestinal parasitic infections. Stool samples collected from 125 children, within a period of 7 months, were examined using direct wet mount and trichrome stain in comparison to in vitro culture on Jones medium (for detecting Blastocystis spp.) and Immunochromatography techniques (for detecting Giardia). At least one type of intestinal parasites was harbored in 72% of the studied children, single infection constituted 37.6% while, 34.4% were polyparasitized children. The predominant parasites involved were Blastocystis spp.(53.6%), followed by Giardia intestinalis (27.2%). Co-infection between both parasites was recorded in 20% of cases. Two risk factors were significantly associated with higher risk of Giardia-Blastocystis co-infection including age category (5-7 years) and family size (≥ 6 members) by univariate analysis (P = 0.004, 0.009 respectively) and also by the multivariate model (OR = 0.526, 0.336). Abdominal pain was the only gastrointestinal manifestation associated with the co-infection using the univariate analysis (P = 0.0427). The present study detects a high prevalence of intestinal parasitic infection; in particular, Giardia-Blastocystis co-infection in diarrheic young children (up to 12 years) in Beni-Suef Governorate, Egypt and recommends further subtypes identification of both parasites.

Amoebic colitis presenting with hypo-albuminaemia in an eight-month-old breastfed girl

Entamoeba histolytica is a protozoan parasite that affects a large proportion of the world's population and causes amoebic dysentery and extra-intestinal disease. Many individuals remain asymptomatic during colonisation; in 10% of individuals, the parasite breaks through the mucosal barrier and leads to invasive disease. An eight-month-old girl who was evaluated for hypo-albuminaemia and was diagnosed with amoebic colitis is reported. To the best of our knowledge, this is the first report of hypo-albuminaemia owing to amoebic colitis in any age group.

Exacerbated symptoms in Blastocystis sp.-infected patients treated with metronidazole: two case studies

Blastocystis sp. is a gastrointestinal (GI) protozoan parasite reported to cause non-specific GI symptoms including diarrhea, flatulence, abdominal pain, and nausea. Complete eradication of Blastocystis sp. is rather challenging even with the drug of choice, i.e., metronidazole. Here, we report on two Blastocystis sp.-infected individuals, who presented increased parasite load and exacerbated symptoms upon treatment with the usual recommended dosage and regime of metronidazole. The two studies uniquely demonstrate for the first time a cyst count as high as fivefold more than the original cyst count before treatment and show an exacerbation of GI symptoms despite treatment. The study provides additional support in recognizing metronidazole resistance in Blastocystis sp. and its consequences towards the pathogenicity of the parasite.

Increase number of mitochondrion-like organelle in symptomatic Blastocystis subtype 3 due to metronidazole treatment

Blastocystis sp., an intestinal organism is known to cause diarrhea with metronidazole regarded as the first line of treatment despite reports of its resistance. The conflicting reports of variation in drug treatment have been ascribed to subtype differences. The present study evaluated in vitro responses due to metronidazole on ST3 isolated from three symptomatic and asymptomatic patients, respectively. Symptomatic isolates were obtained from clinical patients who showed symptoms such as diarrhea and abdominal bloating. Asymptomatic isolates from a stool survey carried out in a rural area. These patients had no other pathogens other than Blastocystis. Ultrastructural studies using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed drug-treated ST3 from symptomatic patients were irregular and amoebic with surface showing high-convoluted folding when treated with metronidazole. These organisms had higher number of mitochondrion-like organelle (MLO) with prominent cristae. However, the drug-treated ST3 from asymptomatic persons remained spherical in shape. Asymptomatic ST3 showed increase in the size of its central body with the MLO located at the periphery.

Update on the pathogenic potential and treatment options for Blastocystis sp

Although Blastocystis is one of the most common enteric parasites, there is still much controversy surrounding the pathogenicity and potential treatment options for this parasite. In this review we look at the evidence supporting Blastocystis as an intestinal pathogen as shown by numerous case studies and several in vivo studies and the evidence against. We describe the chronic nature of some infections and show the role of Blastocystis in immunocompromised patients and the relationship between irritable bowel syndrome and Blastocystis infection. There have been several studies that have suggested that pathogenicity may be subtype related. Metronidazole is the most widely accepted treatment for Blastocystis but several cases of treatment failure and resistance have been described. Other treatment options which have been suggested include paromomycin and trimethroprim- sulfamethoxazole.

Development and evaluation of a real-time PCR assay for detection and quantification of blastocystis parasites in human stool samples: prospective study of patients with hematological malignancies

Blastocystis anaerobic parasites are widespread worldwide in the digestive tract of many animal species, including humans. Epidemiological Blastocystis studies are often limited by the poor sensitivity of standard parasitological assays for its detection. This report presents a highly sensitive real-time quantitative PCR (qPCR) assay developed to detect Blastocystis parasites in stool samples. The assay targets a partial sequence of the Blastocystis small ribosomal subunit (SSU) rRNA gene, allowing subtyping (ST) of Blastocystis isolates by direct sequencing of qPCR products. This qPCR method was assessed in a prospective study of 186 patients belonging to two cohorts--a group of 94 immunocompromised patients presenting hematological malignancies and a control group of 92 nonimmunocompromised patients. Direct-light microscopy and xenic in vitro stool culture analysis showed only 29% and 52% sensitivity, respectively, compared to our qPCR assay. Of the 27 (14.5%) Blastocystis-positive patients, 8 (4%) experienced digestive symptoms. No correlation was found between symptomatic patients and immune status, parasite load, or parasite subtypes, although subtyping of all isolates revealed a high (63.0%) prevalence of ST4. Two unexpected avian subtypes were found, i.e., ST6 and ST7, which are frequently isolated in Asia but rarely present in Western countries. In conclusion, this qPCR proved by far the most sensitive of the tested methods and allowed subtype determination by direct sequencing of qPCR products. New diagnostic tools such as the qPCR are essential for evaluating the clinical relevance of Blastocystis subtypes and their role in acute or chronic digestive disorders.

Eradication of Blastocystis carriage with antimicrobials: reality or delusion?

Metronidazole constitutes a mainstay in the antimicrobial therapy of intestinal protozoa, and is also traditionally considered first-line therapy in cases where there is a requirement to treat Blastocystis, a common protist of disputable clinical significance. Many compounds have been used in attempts to eradicate the parasite, and an accumulating body of data indicates that successful antimicrobial eradication of Blastocystis is far from straightforward. This review focuses on some issues that prevent us from reaching a clear understanding of how to eradicate Blastocystis based on chemotherapeutic intervention, by focusing on conflicting reports on the efficacy of metronidazole and other compounds and study design and data limitations. The review provides a comprehensive overview of antimicrobials used to target Blastocystis, and discusses issues pertaining to drug resistance, treatment failure, and reinfection. Finally, key methodological and molecular diagnostic tools that will assist in the generation of data required to improve current knowledge are identified and discussed.

Pursuing the clinical significance of Blastocystis--diagnostic limitations

The clinical significance of one of the most prevalent single-celled intestinal parasites worldwide, Blastocystis, remains unsettled. A plethora of clinical and epidemiological studies have been undertaken to generate data on its prevalence in different populations and investigate the role of the parasite as a cause of gastro- and extra-intestinal disease. In this article, we pinpoint limitations of studies that seek to determine the clinical significance of Blastocystis, based on shortcomings in our understanding of Blastocystis diagnosis and biology, and identify methodologies for further studies aimed at determining the molecular epidemiology and clinical impact of this parasite.

New insights on classification, identification, and clinical relevance of Blastocystis spp

SUMMARY

Blastocystis is an unusual enteric protozoan parasite of humans and many animals. It has a worldwide distribution and is often the most commonly isolated organism in parasitological surveys. The parasite has been described since the early 1900s, but only in the last decade or so have there been significant advances in our understanding of Blastocystis biology. However, the pleomorphic nature of the parasite and the lack of standardization in techniques have led to confusion and, in some cases, misinterpretation of data. This has hindered laboratory diagnosis and efforts to understand its mode of reproduction, life cycle, prevalence, and pathogenesis. Accumulating epidemiological, in vivo, and in vitro data strongly suggest that Blastocystis is a pathogen. Many genotypes exist in nature, and recent observations indicate that humans are, in reality, hosts to numerous zoonotic genotypes. Such genetic diversity has led to a suggestion that previously conflicting observations on the pathogenesis of Blastocystis are due to pathogenic and nonpathogenic genotypes. Recent epidemiological, animal infection, and in vitro host-Blastocystis interaction studies suggest that this may indeed be the case. This review focuses on such recent advances and also provides updates on laboratory and clinical aspects of Blastocystis spp.

Viable blastocystis cysts in Scottish and Malaysian sewage samples

Blastocystis cysts were detected in 38% (47/123) (37 Scottish, 17 Malaysian) of sewage treatment works. Fifty percent of influents (29% Scottish, 76% Malaysian) and 28% of effluents (9% Scottish, 60% Malaysian) contained viable cysts. Viable cysts, discharged in effluent, provide further evidence for the potential for waterborne transmission of Blastocystis.

Comparison of methods for detecting Blastocystis hominis

In order to determine the comparative sensitivity of two methods of detecting Blastocystis hominis and to investigate the seasonality of infection with this enteric protozoan parasite, the present study was conducted. In each of two 3-month periods representing winter, spring (February-April) and summer (July-September), 500 routine stool submissions were examined for B. hominis using microscopy following either formol-ether concentration or in vitro culture using Jones' medium. The organism was detected in 39 of the 1,000 samples investigated using the in vitro culture technique and in none of the samples using the formol-ether concentration technique. In 82% of the B. hominis-positive samples, no concurrent bacterial or parasitic pathogens were found, and diarrhoea was the most commonly recorded symptom among patients. Infection was more prevalent in summer than in winter/spring, occurring primarily in the 71-80-year age group. Cysts were detected in 20.5% of positive samples, but only following Ficoll-Paque concentration of formol-ether concentrates. Cyst excretion was more prevalent in summer than in winter/spring.