Subtype distribution and molecular characterization of Blastocystis from hemodialysis patients in Turkey.

INTRODUCTION: The aim of this study was to determine the Blastocystis prevalence and subtypes in hemodialysis patients in Turkey. METHODOLOGY: Eighty-four patients diagnosed with end-stage renal failure who were undergoing hemodialysis and 20 healthy volunteers were enrolled. Blastocystis presence was investigated by native-Lugol, trichrome staining, PCR using STS primers, and DNA sequencing analysis. RESULTS: Among the stool samples from the hemodialysis patients, 9.52% (8/84) were found to be Blastocystis-positive with the native-Lugol and trichrome staining. Seven of the eight Blastocystis isolates were subtyped using STS primers. Blastocystis subtype distribution was as follows: one had ST1, two had ST2, two had ST3, two had ST3+ST6, and one was not subtyped. Blastocystis positivity was detected in two healthy control (2/20, %10), one subject had ST1, and the other was not subtyped. All subtypes identified by PCR were confirmed by the sequencing analysis. In the two samples that had mixed subtypes (ST3+ST6) when using the STS primers, only ST3 was detected in the sequencing analysis. Although some patients have multiple symptoms, the most common symptoms in Blastocystis positive patients were bloating (5/8), diarrhea (4/8), nausea and vomiting (2/8), and gas and weight loss (1/8). Also, only one patient had Giardia intestinalis. CONCLUSIONS: This was the first study to determine the Blastocystis subtypes in hemodialysis patients. A rare subtype, ST6, was identified in two of the patients. Thus, the ST6 infections were attributable to transmission from poultry infections. The presence of this unusual subtype suggests the need for further extensive studies of hemodialysis patients.

Molecular characterization of Blastocystis subtypes in HIV-positive patients and evaluation of risk factors for colonization.

BACKGROUND: Blastocystis is one of the most common intestinal protozoa in human faecal samples with uncertain impact on public health. Studies on the prevalence of Blastocystis in HIV-positive patients are limited and dated. METHODS: A cross-sectional study was carried out involving 156 HIV-positive patients to evaluate the prevalence of Blastocystis-subtypes by molecular amplification and sequencing the small subunit rRNA gene (SSU rDNA), to identify the risk factors for its transmission, to examine the relationship between the presence of the protist and gastrointestinal disorders. Furthermore, the evaluation of the faecal calprotectin by immunoassay from a sample of subjects was performed to evaluate the gut inflammation in Blastocystis-carriers. RESULTS: Blastocystis-subtypes ST1, ST2, ST3, ST4 were identified in 39 HIV-positive patients (25%). No correlation was found between the presence of the protist and virological or epidemiological risk factors. Blastocystis was more frequently detected in homosexual subjects (p = 0.037) infected by other enteric protozoa (p = 0.0001) and with flatulence (p = 0.024). No significant differences in calprotectin level was found between Blastocystis-carriers and free ones. CONCLUSIONS: Blastocystis is quite common in HIV-positive patients on ART showing in examined patients 25% prevalence. Homosexual behaviour may represent a risk factor for its transmission, while CD4 count and viremia didn't correlate with the presence of the protist. The pathogenetic role of Blastocystis remains unclear and no gut inflammation status was detected in Blastocystis-carriers. The only symptom associated with Blastocystis was the flatulence, evidencing a link between the presence of the protist and the composition and stability of gut microbiota.

Prevalence, Characteristics, Risk Factors, and Impact of Intestinal Parasitic Infections on School Children in Jeddah, Western Saudi Arabia.

Intestinal Parasitic Infections (IPIs) are a major public health problem worldwide, especially among children with a need for periodical evaluation of prevalence and risk factors to adopt an appropriate prevention strategy. This cross-sectional prospective study was conducted to identify prevalence, risk factors, characteristics, and impact of IPIs on school children in different regions of Jeddah, Saudi Arabia. Children were recruited from randomly selected schools. Questionnaires were distributed to students and filled by their parents to collect relevant information about sociodemographic, environmental, and hygienic living conditions. Stool samples and anthropometric measurements as indicators of nutritional status were collected from students who agreed to participate in the study. Fecal samples were examined by direct smear and formol-ether concentration method. Out of 581 collected stool samples, only 31 (5.3%) samples were positive for IPIs especially Blastocystis hominis (10 samples) and Giardia lamblia (six samples). The only two significant risk factors associated with IPIs were drinking water from tanks [odds ratio (OR): 3.35, 95% confidence interval (CI): 1.60-6.99, p = 0.001] and washing hands with only water (OR: 2.63, 95% CI: 1.17-5.93, p = 0.03). There was no significant impact of IPIs on growth parameters or level of children's academic performance.

High diversity of Blastocystis subtypes isolated from asymptomatic adults living in Chiang Rai, Thailand.

Blastocystis is a common and broadly distributed microbial eukaryote inhabiting the gut of humans and other animals. The genetic diversity of Blastocystis is extremely high comprising no less than 17 subtypes in mammals and birds. Nonetheless, little is known about the prevalence and distribution of Blastocystis subtypes colonising humans in Thailand. Molecular surveys of Blastocystis remain extremely limited and usually focus on the central, urban part of the country. To address this knowledge gap, we collected stool samples from a population of Thai adults (n = 178) residing in Chiang Rai Province. The barcoding region of the small subunit ribosomal RNA was employed to screen for Blastocystis and identify the subtype. Forty-one stool samples (23%) were identified as Blastocystis positive. Six of the nine subtypes that colonise humans were detected with subtype (ST) three being the most common (68%), followed by ST1 (17%) and ST7 (7%). Comparison of subtype prevalence across Thailand using all publicly available sequences showed that subtype distribution differs among geographic regions in the country. ST1 was most commonly encountered in the central region of Thailand, while ST3 dominated in the more rural north and northeast regions. ST2 was absent in the northeast, while ST7 was not found in the center. Thus, this study shows that ST prevalence and distribution differs not only among countries, but also among geographic regions within a country. Potential explanations for these observations are discussed herewith.

Protozoos intestinales en un asentamiento precario: manifestaciones clínicas y ambiente / Intestinal protozoa in a marginal settlement: clinical manifestations and environment

Los objetivos de este trabajo fueron conocer la distribución de Blastocystis hominis y Giardia lamblia en un asentamiento del Partido de La Plata (Buenos Aires), evaluar si su infección tiene manifestaciones clínicas y si su asociación con especies comensales es indicadora de la influencia de factores ambientales. Se tomaron 194 muestras fecales en 78 familias, que se analizaron mediante las técnicas de Ritchie, Carles Barthelemy y Willis. Se completaron encuestas con datos ambientales, sociales y del entorno de las viviendas. Se buscaron parásitos intestinales en muestras de agua. El 69,1% de los analizados (85,8% de las familias) estuvo parasitado con protozoos. En el 87% de los hogares positivos, hubo casos de poliparasitismo. Las especies más frecuentes fueron Blastocystis hominis y Giardia lamblia, que no se hallaron asociadas entre sí, ni con los síntomas digestivos estudiados. Blastocystis hominis se asoció con Endolimax nana (p<0,01), Entamoeba coli (p<0,01) y Enteromonas hominis (p<0,05). Ambas especies patógenas fueron más frecuentes entre las familias numerosas que viven en condiciones de hacinamiento (p≤0,05). Giardia lamblia se asoció con la promiscuidad (p<0,05) y la convivencia con caninos (p<0,01). La presencia de quistes de amebas comensales en el agua de las viviendas analizadas demuestra que ésta puede ser un factor de riesgo de infección parasitaria si no es debidamente purificada. Son necesarios mayores controles sanitarios que procuren una disposición segura de las excretas humanas y animales.

The aims of this study were to know the distribution of Blastocystis hominis and Giardia lamblia in a suburban settlement of La Plata district, Buenos Aires province, to evaluate if infections have clinical manifestations, and to determine if the association with commensal species is influenced by environmental factors. A hundred and ninety-four faecal samples of 78 families were examined using Ritchie, Carles Barthelemy and Willis techniques, and also water samples were analyzed for intestinal protozoans. Environmental and social questionnaires were fulfilled. Of the analyzed persons, 69.1% (85.8% of the families) were infected with protozoans. Eighty-seven per cent of the positive families were poli-parasitized. Blastocystis hominis and Giardia lamblia were the most frequent species and they were not associated with each other, neither with the digestive symptoms. Blastocystis hominis was associated with Endolimax nana (p<0.01), with Entamoeba coli (p<0.01) and with Enteromonas hominis (p<0.05). Giardia lamblia was associated with promiscuity (p<0.05) and the coexistence of dogs (p<0.01). The presence of cysts of commensal amoebas in the water analyzed demonstrates it could be a risk factor of parasitic infection. More strict sanitary controls are needed to avoid the faecal contamination of the environment.

Clinical characteristics and endoscopic findings associated with Blastocystis hominis in healthy adults.

Ninety-nine individuals with stools positive for Blastocystis hominis but negative for other parasites were identified from medical records of healthy adults who had received a physical examination at Taipei Veterans General Hospital from November 2000 to October 2002. The medical records of these 99 positive cases and 193 randomly selected controls, matched for age, sex, and date of examination, were retrospectively reviewed. The pathogenicity of B. hominis could not be demonstrated due to a lack of association with the development of gastrointestinal symptoms or pathologic findings on endoscopic examination. Multivariate analyses revealed that chronic hepatitis B infection was a predisposing condition to the acquisition of B. hominis (odd ratio = 2.848, 95% confidence interval = 1.299-6.242, P = 0.009), and concentration of urate was significantly lower in B. hominis-positive individuals (mean +/- SD = 361.64 +/- 87.44 versus 392.57 +/- 93.38 micromol/L; P = 0.009). Among the 64 individuals who underwent gastric biopsy, Helicobacter pylori was found more frequently in the individuals harboring B. hominis (19 of 26 versus 15 of 38; P = 0.017).

A placebo-controlled treatment trial of Blastocystis hominis infection with metronidazole.

Blastocystis hominis, previously considered a harmless yeast, is now classified as a protozoan inhabiting the human intestinal tract. The pathogenicity of B. hominis remains controversial and is currently the subject of extensive debate.1- 5 As a result of the uncertainty surrounding the pathogenic role of B. hominis, large-scale treatment trials of B. hominis infection have so far been lacking. In spite of this, several drugs have been reported to be active against the parasite.6-8 The present study was carried out in order to evaluate the efficacy of metronidazole treatment in inducing clinical remission and parasitologic eradication in immunocompetent individuals with B. hominis as the only evident cause of diarrhea.

Blastocystis hominis en pacientes del Hospital Universitario Ruíz y Páez de Ciudad Bolivar, Venezuela / Blastocystis hominis in patients at Hospital Universitario Ruíz y Páez, Bolivar city, Venezuela

Blastocystis hominis is a polymorphic protozoan of discussed taxonomic position, which is currently associated with human intestinal disease. In order to determine the prevalence of the microorganism in a sample of hospitalized patients, a study was carried out from november 1996 to april 1997 on 100 adult patients of both sexes aged 20 to 79 years at the Ruíz y Páez University Hospital of Bolivar city, Venezuela. A coproparasitological study was carried out using direct examination and Faust method. Infection by parasites and/or commensals was demostrated in 48 patients. The most frequent agent was B. hominis with a prevalence of 42,0 percent. We did not find a statistically association between sex (p > 0,05) or age (X²=3.52: d.f; =3) and B. hominis infection. B. hominis was most frequently identified as the single parasite (88,1 percent), and with a number of less than 5 cells per 400X microscopic field (73,8 percent). The infection was more common in patients with base chronic-immunosuppressive diseases, the major one being cancer. Diarrhea was observed in 27,0 percent of cases. Due to its high prevalence, especially as a single agent, together with the particular immunological characteristics of the patients studied, a potential pathogenic role of the opportunistic type is suggested for B. hominis

Acute GVHD involving the gastrointestinal tract and infestation with Blastocystis hominis in a patient with chronic myeloid leukaemia following allogeneic bone marrow transplantation.

A 21-year-old female underwent allogeneic bone marrow transplantation (ABMT) from her HLA matched brother for chronic myeloid leukaemia in the chronic phase. Four weeks post transplant she developed tenesmus, mucoid stool mixed with blood and lower abdominal pain. This rapidly progressed to greenish watery diarrhoea with flakes of mucous membrane floating in it, conforming to the classical clinical description of acute GVHD of the bowel. Stool microscopy showed profuse numbers of Blastocystis hominis, a parasite with doubtful pathogenicity in an immunocompetent host. In the present case the parasite played a pathogenic role as evidenced by the profuse number in the stool sample, focal neutrophil infiltration of the rectal mucosa, initial presentation of the patient with dysentery, and requirement for prolonged metronidazole therapy to eradicate the parasite and cure the diarrhoea. She also had grade I GVHD of the liver and skin. In developing tropical countries, hitherto unreported parasitic infestations may complicate the picture of acute GVHD.

Cryptosporidiosis and blastocystosis in renal transplant recipients.

Some intestinal parasitic infections are frequently seen in renal transplant recipients. Parasites such as Cryptosporidium spp. and Blastocystis hominis are often asymptomatic or responsible for limited infections in normals, but may cause prolonged and heavy infections with gastrointestinal complaints, mainly diarrhea, in immunocompromised patients. Such infections can often not be detected by routine diagnostic procedures, but special concentration and staining methods are needed. We investigated 115 fecal specimens from 69 renal transplant recipients and 42 fecal specimens from 42 control cases. Of the 69 recipients, 27 (39.1%) had B. hominis and 13 (18.8%) had Cryptosporidium spp. in at least one fecal specimen. Prevalence of symptomatic Cryptosporidium infections was significantly higher in the renal transplant recipients, when compared with the control group (p < 0.05). Special parasitological procedures must be performed in immunocompromised patients with chronic gastrointestinal complaints. Disappearance of symptoms after antiparastic drugs in some of 16 symptomatic patients are described, suggesting that these infections are more pathogenic in transplant recipients.

Blastocystis hominis revisited.

Blastocystis hominis is a unicellular organism found commonly in the intestinal tract of humans and many other animals. Very little is known of the basic biology of the organism, and controversy surrounds its taxonomy and pathogenicity. There morphological forms (vacuolar, granular, and ameboid) have been recognized, but recent studies have revealed several additional forms (cyst, avacuolar, and multivacuolar). The biochemistry of the organism has not been studied to any extent, and organelles and structures of unknown function and composition are present in the cells. Several life cycles have been proposed but not experimentally validated. The form used for transmission has not been defined. Infections with the organism are worldwide and appear in both immunocompetent and immunodeficient individuals. Symptoms generally attributed to B. hominis infection are nonspecific, and the need for treatment is debated. If treatment appears warranted, metronidazole is suggested as the drug of choice, although failures of this drug in eradicating the organism have been reported. Infection is diagnosed by light microscopic examination of stained smears or wet mounts of fecal material. Most laboratories identify B. hominis by observing the vacuolar form, although morphological studies indicate that other forms, such as the cyst form and multivacuolar form, also should be sought for diagnosis.

Identification of surface coat carbohydrates in Blastocystis hominis by lectin probes.

The carbohydrate residues of the surface coat of 20 axenic cultures of Blastocystis hominis were studied using FITC-labelled lectins (ConA, WGA, DBA, HPA, SBA, PNA, UEAI and LPA). The specific affinity of reactive lectins was determinated by competitive inhibition assay with specific carbohydrates or by enzymatic pre-treatment of cells. All stocks strongly bound ConA and HPA; WGA, UEAI and LPA were partially reactive, and the remaining lectins were nonreactive. Inhibition assays showed abolition (WGA, LPA, UEAI and HPA) or partial reduction (ConA) of lectin affinity, which demonstrated the specificity of binding assay. These results indicate that B. hominis has surface components containing alpha-D-mannose, alpha-D-glucose, N-acetyl-alpha-D-glucosamine, alpha-L-fucose, chitin and sialic acid.

[Protozoan infection (Blastocystis hominis) concomitant with Pseudomonas sp. peritonitis in continuous ambulatory peritoneal dialysis (CAPD)]. / Infezione protozoaria (Blastocystis hominis) concomitante a peritonite da Pseudomanas sp. in corso di dialisi peritoneale ambulatoriale continua (CAPD).

Case-report of protozoal infection (Blastocystis bominis) during Pseudomonas peritonitis in male patient with intestinal diverticulosis on continuous ambulatory peritoneal dialysis (CAPD) treatment for chronic renal failure (CRF). Microscopic morphology and cultural characteristics are summarized from current literature. Photographic images in phase contrast from fresh-observation of faeces and peritoneal fluid are reported. Although other Protozoa (e.g. Acanthamoeba free-living) have already been found in dialysis fluid, this is the first case, referred in literature, of Blastocystis bominis infection in CAPD patients. Some pathogenetic hypothesis are done involving Blastocystis bominis in peritoneal infection, especially in immunodepressed patients like dialysed ones. Although many chemotherapeutics are provided for this protozoiasis during enteritis, in our case no supplement was required except specific antibiotic therapy for Pseudomonas infection. Symbion or pathogen? Is now-a-day the question which troubles parasitologists. Systemic research of Protozoa in dialysed patients is anyhow advisable.

Blastocystosis en pacientes sintomáticos del hospital regional de Temuco, Chile / Blastocystosis in symptomatic patients at the regional hospital of Temuco, Chile

Se comprobó la persistenci de altos indices de enteroparásitos en general y de B. homisis en particular. La frecuencia global de B. homisis como agente único en individuos sintomáticos, supera el promedio descrito en otros estudios de distintas zonas de nuestro país y términos de infecciones mixtas o asociadas, un tercio de las infecciones por G. intestinalis y casi la mitad de las causadas por E. histolytica coexistían con el nuevo agente protozoario. Lo anterior debiera ser justamente valorado desde un punto de vista clínico, terapéutico y epidemiológico, dado que aún se discuten los mecanismos patogénicos de esta entidad (Sheehan y col., 1966). Por último, deseamos enfatizar que el laboratorio debe acompañar el hallazgo de B. homisis de un informe cuantitativo de la carga parasitaria, considerando las recomendaciones que estiman que un número superior a cinco formas de este protozoario por campo microscópico (40x) costituirían una carga suficiente para producir cuadros clínicamente sintomáticos y que en ausencia de otros patógenos, en clínica se deben abordar terapéuticamente los casos (Zierdt, 1983)

Prevalence and characteristics of Blastocystis hominis infection in children.

Blastocystis hominis, a protozoan whose pathogenicity has been questioned, is sometimes found in the human gastrointestinal tract. We sought to determine the prevalence of Blastocystis in stool and to characterize clinical features of infection with Blastocystis in children. Forty-six (3%) of 1,736 patients undergoing fecal microscopy at Children's Hospital of Pittsburgh between January 1, 1985, and December 31, 1988, harbored Blastocystis. Of these 46 children, 75% had exposure to well water or had been in developing countries. Thirty-nine of the 46 (85%) experienced gastrointestinal symptoms, such as abdominal pain, diarrhea, vomiting, and weight loss. Blastocystis was the only parasite found in 35 of those 39 symptomatic children. Symptoms resolved within one month in 90% of patients receiving antiparasitic pharmacotherapy, but in only 58% (P < .04) of those receiving no therapy. We conclude that children infected with Blastocystis often experience gastrointestinal symptoms and that treatment increases the rate of symptomatic improvement. We speculate that Blastocystis is a human pathogen.