Characteristics of Factors of Protozoa Blastocystis hominis Persistence.

Persistence activity manifested in the expression of anti-lysozyme, anti-lactoferrin, and antihistone factors promoting inactivation of natural anti-infection resistance factors in the body was revealed in Blastocystis hominis protozoa. Activities of these factors were ranged. The frequency of these factors in clinical isolates of blastocyst decreased in the following order: anti-lactoferrin activity (84.5±3.7%)→anti-lysozyme activity (64.8±5.7%)→anti-histone activity (48.1±2.3%). In healthy humans, the corresponding parameters were 7.3±1.3, 5.3±0.9, and 3.3±0.4%, respectively (p<0.05). It was shown that the studied activities in highly virulent blastocysts were higher than in groups of medium-, low-, and avirulent protozoa.

[Relationship between morphology and pathogenicity of Blastocystis hominis trophozoites].

Six hundred and eighty-six fresh fecal specimens were collected from outpatients (663 well-formed feces and 23 watery feces) during March 2011 to March 2012. All specimens were examined microscopically by direct smear and iodine stained method. B. hominis obtained from the human positive fecal specimens were cultured in LES medium, and inoculated into the abdominal cavity of 10 female mice of 6-8-week old. The abdominal fluid was examined with same methods. 103 of 686 patients were positive (80 well-formed feces and 23 watery feces). Micro-scopically, the granular form and vacuolated form of B. hominis trophozoites could be easily identified by direct smear and iodine staining in well-formed fecal specimens, showing ovoid in shape and about (13.2 +/- 0.2) microm in size. The trophozoites cultured in LES medium showed similar feature. But in the watery fecal specimens and mice ascites specimen, they were amorphous containing more granules. And their average size was (28.0 +/- 0.3) microm which was larger than the former. Moreover, the ameba form of B. hominis trophozoites was also detected in the 23 watery fecal specimen and mice ascites specimen. The trophozoites of B. hominis were varying in shape and size depending on their living environment.

No advantage for antibiotic treatment over placebo in Blastocystis hominis-positive children with recurrent abdominal pain.

OBJECTIVE: The aim of the study was to investigate whether recurrent abdominal pain (RAP) in Blastocystis hominis-positive children can be treated successfully with trimethoprim-sulfamethoxazole (TMP/SMX). METHODS: From October 2004 to December 2008, all of the patients referred to the Division of Gastroenterology and Nutrition of the University Children's Hospital Zurich because of RAP and detection of B hominis in stool samples as the only pathological finding after a standard workup were offered to participate in the study. Patients were randomly assigned into 2 groups. TMP/SMX or placebo was given for 7 days in a double-blind, placebo-controlled manner. Pain index (PI) was measured with a visual analogue scale. Two weeks after completion of treatment, 3 stool samples were collected and patients were followed clinically. If B hominis was still present, metronidazole was given for 7 days. RESULTS: Forty patients were included; 37 finished the study (TMP/SMX n = 20, placebo n = 17). Mean PI declined from 7.1 to 3.6 for all of the patients, with a decrease from 6.9 to 4.1 in the TMP/SMX and 7.4 to 3.0 in the placebo group, irrespective of detection of B hominis after treatment. There was no statistically significant difference in PI reduction between the 2 groups. Metronidazole treatment led to a further PI decline from 3.7 to 1.9. Eradication rates were 35% (TMP/SMX) and 44% (metronidazole), compared with spontaneous clearance of 29% in the placebo group. CONCLUSIONS: There is no advantage for TPM/SMX over placebo in the treatment of RAP in B hominis-positive children.

Effects of symptomatic and asymptomatic isolates of Blastocystis hominis on colorectal cancer cell line, HCT116.

The pathogenesis of Blastocystis hominis in human hosts has always been a matter of debate as it is present in both symptomatic and asymptomatic individuals. A recent report showed that B. hominis isolated from an asymptomatic individual could facilitate the proliferation and growth of existing cancer cells while having the potential to downregulate the host immune response. The present study investigated the differences between the effects of symptomatic and asymptomatic derived solubilized antigen of B. hominis (Blasto-Ag) on the cell viability and proliferation of colorectal cancer cells. Besides that, the gene expression of cytokine and nuclear transcriptional factors in response to the symptomatic and asymptomatic B. hominis antigen in HCT116 was also compared. In the current study, an increase in cell proliferation was observed in HCT116 cells which led to the speculation that B. hominis infection could facilitate the growth of colorectal cancer cells. In addition, a more significant upregulation of Th2 cytokines observed in HCT116 may lead to the postulation that symptomatic Blasto-Ag may have the potential in weakening the cellular immune response, allowing the progression of existing tumor cells. The upregulation of nuclear factor kappa light chain enhancer of activated B cells (NF-κB) was observed in HCT116 exposed to symptomatic Blasto-Ag, while asymptomatic Blasto-Ag exhibited an insignificant effect on NF-κB gene expression in HCT116. HCT116 cells exposed to symptomatic and asymptomatic Blasto-Ag caused a significant upregulation of CTSB which lead to the postulation that the Blasto-Ag may enhance the invasive and metastasis properties of colorectal cancer. In conclusion, antigen isolated from a symptomatic individual is more pathogenic as compared to asymptomatic isolates as it caused a more extensive inflammatory reaction as well as more enhanced proliferation of cancer cells.

The potential use of 29 kDa protein as a marker of pathogenicity and diagnosis of symptomatic infections with Blastocystis hominis.

The present study was performed to characterize the protein profiles of Blastocystis hominis isolates from symptomatic and asymptomatic individuals by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using sera from symptomatic and asymptomatic patients. The presence of immunogenic bands associated with pathogenicity or of diagnostic potentials was also evaluated. The study comprised 80 individuals classified into four groups, 20 each: symptomatic blastocystosis (G1), asymptomatic blastocystosis (G2), other parasitic infections (G3), and healthy control subjects (G4). SDS-PAGE analysis of individual antigens form symptomatic and asymptomatic B. hominis isolates revealed similar and distinctive antigenic bands with significant differences in two high (123.5 and 112.3 kDa) and few low molecular weight bands (48.5, 38, 42.3, and 35.5 kDa). Immunoblotting was performed using symptomatic and asymptomatic antigen pools with sera of the four studied groups. It was found that anti-B. hominis IgG reacted with nine protein bands ranging from 100 to 18 kDa of the symptomatic antigen pool. There was a significant difference between G1 and G2 in the recognition of 64, 56, 38, and 29 kDa antigen bands. Also, anti-B. hominis IgG reacted with five protein bands ranging from 56 to 12 kDa of asymptomatic antigen pool. There was a significant difference between G1 and G2 in the recognition of 29 kDa antigen band. These findings suggest the potential use of the 29-kDa antigen as marker of pathogenicity and implicate its use in the diagnosis and differentiation between symptomatic and asymptomatic blastocystosis.

Clinical efficacy of Saccharomyces boulardii or metronidazole in symptomatic children with Blastocystis hominis infection.

Although many Blastocystis infections remain asymptomatic, recent data suggest it also causes frequent symptoms. Therapy should be limited to patients with persistent symptoms and a complete workup for alternative etiologies. The goal of this study was to compare the natural evolution (no treatment) to the efficacy of Saccharomyces boulardii (S. boulardii) or metronidazole for the duration of diarrhea and the duration of colonization in children with gastrointestinal symptoms and positive stool examination for Blastocystis hominis. This randomized single-blinded clinical trial included children presenting with gastrointestinal symptoms (abdominal pain, diarrhea, nausea-vomiting, flatulence) more than 2 weeks and confirmed B. hominis by stool examination (B. hominis cysts in the stool with microscopic examination of the fresh stool). The primary end points were clinical evaluation and result of microscopic stool examination at day 15. Secondary end points were the same end points at day 30. Randomization was performed by alternating inclusion: group A, S. boulardii (250 mg twice a day, Reflor®) during 10 days; group B, metronidazole (30 mg/kg twice daily) for 10 days; group C, no treatment. At day 15 and 30 after inclusion, the patients were re-evaluated, and stool samples were examined microscopically. On day 15, children that were still symptomatic and/or were still B. hominis-infected in group C were treated with metronidazole for 10 days. There was no statistically significant difference between the three study groups for age, gender, and the presence of diarrhea and abdominal pain. On day 15, clinical cure was observed in 77.7% in group A (n, 18); in 66.6% in group B (n, 15); and 40% in group C (n:15) (p < 0.031, between groups A and C). Disappearance of the cysts from the stools on day 15 was 80% in group B, 72.2% in group A, and 26.6% in group C (p = 0.011, between group B and group C; p = 0.013, between group A and group C). At the end of the first month after inclusion, clinical cure rate was 94.4% in group A and 73.3% in group B (p = 0.11). Parasitological cure rate for B. hominis was very comparable between both groups (94.4% vs. 93.3%, p = 0.43). Metronidazole or S. boulardii has potential beneficial effects in B. hominis infection (symptoms, presence of parasites). These findings challenge the actual guidelines.

Prevalence and genetic characteristics of Blastocystis hominis and Cystoisospora belli in HIV/AIDS patients in Guangxi Zhuang Autonomous Region, China.

Blastocystis hominis and Cystoisospora belli are considered to be common opportunistic intestinal protozoa in HIV/AIDS patients. In order to investigate the prevalence and genetic characteristics of B. hominis and C. belli in HIV/AIDS patients, a total of 285 faecal samples were individually collected from HIV/AIDS patients in Guangxi, China. B. hominis and C. belli were investigated by amplifying the barcode region of the SSU rRNA gene and the internal transcribed spacer 1 (ITS-1) region of the rRNA gene, respectively. Chi-square test or Fisher's exact test were conducted to assess the risk factors related to B. hominis and C. belli infection. The prevalence of B. hominis and C. belli was 6.0% (17/285) and 1.1% (3/285) respectively. Four genotypes of B. hominis were detected, with ST3 (n = 8) and ST1 (n = 6) being predominant, followed by ST6 (n = 2) and ST7 (n = 1). Females had a statistically higher prevalence of B. hominis (11.6%) than males (4.2%). The statistical analysis also showed that the prevalence of B. hominis was significantly associated with age group and educational level. Our study provides convincing evidence for the genetic diversity of B. hominis, which indicates its potential zoonotic transmission and is the first report on the molecular characteristics of C. belli in HIV/AIDS patients in China.

Encystation--survival of Blastocystis hominis in immunocompetent mice abdomen cavity.

Human Blastocystis hominis were isolated from diarrhea patients' feces and cultured in vitro. Then the cultures were inoculated intraperitoneally to laboratory mice. The B. hominis in living mice were collected and inoculated again to healthy mice. The B. hominis showed dose-dependent pathogenicity in the primary inoculation. No pathogenicity was observed in the secondary inoculation. The protozoan existed in the living mice abdomen cavity for more than 6 months and the cyst was the only form. These results showed that encystation enable the parasite to avoid the immune attack in competent host and simultaneously decrease the pathogenicity to host. Intraperitoneal inoculation to laboratory mice is a good method to maintain and propagate B. hominis. This is also a good model to study the interaction of B. hominis and immune system.

Pathogenic potential of Blastocystis hominis in laboratory mice.

Blastocystis hominis is a ubiquitous enteric protozoan whose pathogenic potential is still controversial. This study was carried out to clarify the pathogenecity of B. hominis infection and to study the proper number of parasites for mice infection. A total of 15 albino mice were orally inoculated with B. hominis and divided according to the inoculums, 10(2), 10(5), and 4 x 10(7) B. hominis forms/100 microl saline, into three groups consisting of five mice each, GI, GII GIII, respectively. In addition with group IV (uninfected control) consisting of five mice. All mice were sacrificed 2 weeks post-infection. The results revealed that all mice of GIII and two mice of GII got the infection while all mice of GI showed a completely negative result. Histopathological examination of large intestine on highly infected group (GIII) showed that B. hominis infiltrated the lamina propria, the submucosa, and the muscle layers in the form of collection of vacuolar forms. This was accompanied by active colitis with infiltration of mixed inflammatory cells. In conclusion, this study revealed that large number of B. hominis is essential for oral infection of mice and that vacuolar forms of B. hominis can invade the lamina propria, the submucosa, and even the muscle layers.

Identification of Blastocystis hominis isolates from asymptomatic and symptomatic patients by PCR.

Despite years of study, the pathogenic role of Blastocytis hominis is still controversial. Genotypic differences between the asymptomatic and symptomatic isolates should assist in determining the pathogenicity of Blastocystis. In this study, we genotyped 32 Blastocystis isolates obtained from 12 asymptomatic healthy individuals and 20 symptomatic patients pain by polymerase chain reaction using known seven kinds of sequence tagged site primers in this study. When we compared genotype of Blastocystis isolates between the symptomatic and asymptomatic patient group, we found that subtype3 is the most dominant genotype in asymptomatic individual (9/12) and subtype1 determined all of symptomatic patients (20/20).

A Cross-Sectional Study on Intestinal Parasitic Infections in Children in Suburban Public Primary Schools, Saraburi, the Central Region of Thailand.

Intestinal parasitic infection rate among school-aged children in Thailand has been decreasing. However, certain intestinal parasites remain problematic in some regions. This cross-sectional study was conducted between February and September 2016 in three suburban government primary schools (KK, BR, and HK), Saraburi, Thailand. Stool was collected from 263 asymptomatic subjects (4-15 years old), using simple direct smear, formalin-ether concentration, Boeck and Drbohlav's Locke-Egg-Serum (LES) medium culture, and agar plate culture. A self-administered questionnaire was used to collect data about lifestyle and socioeconomic status. The overall rate of intestinal parasites was 22.1% (15.6% single infection and 6.5% multiple infections). The helminths involving the digestive system found were Strongyloides stercoralis (1.5%) and Opisthorchis viverrini (0.4%). For protozoan infection, the major cause was Blastocystis hominis (17.5%). The other protozoa included Endolimax nana (4.6%), Entamoeba coli (3.4%), Entamoeba histolytica/Entamoeba dispar (1.1%), and Giardia intestinalis (0.8%). The sensitivity for the detection of B. hominis increased with the LES culture technique. The infection rate of each organism was not significantly different among the three schools except for B. hominis which showed the highest prevalence in the HK school (P = 0.001). This was correlated with the questionnaire results in which the HK school showed the highest risk of drinking contaminated water (P = 0.004). The present study emphasized the persistent problems of protozoan infections among suburban school-aged children. Lifestyle was still an important factor for intestinal parasitic infections among suburban school-aged Thai children in this study. Health education as well as routine surveillance was necessary to control the infections.

Infectivity of different genotypes of human Blastocystis hominis isolates in chickens and rats.

Most Blastocystis hominis isolates from humans are believed to be potentially zoonotic. This is because B. hominis isolates found in a variety of other host species have been found to have identical or relatively similar genotypes to those found in human isolates. However, the transmission of human B. hominis isolates to other animals has not been confirmed experimentally. In this study, the infectivity associated with several unique human Blastocystis genotypes (subtypes 2, 3, 4 and 7) was therefore investigated by infecting chickens and rats with two isolates of each subtype experimentally. The results showed that one isolate of subtype 4 and one isolate of subtype 7 was capable of infecting both chickens and rats, while two isolates of subtype 2, another isolate of subtype 4, and another isolate of subtype 7 could only infect chickens. Conversely, two isolates of subtype 3 failed to infect either of the animals. These results confirmed that several genotypes from human isolates could infect chickens and/or rats, indicating that chickens and rats are suitable experimental animal models for studying the zoonotic potential of human Blastocystis isolates.

Dolor abdominal crónico en un niño con Blastocystis hominis: a propósito de un caso / Chronic abdominal pain in a child with Blastocystis hominis: case report

RESUMEN El Blastocystis sp. es un parásito frecuente en el humano, identificado por el laboratorio en muestras de heces fecales. Se presentó el caso de un paciente de 5 años atendido en consulta de Gastroenterología en el Hospital Pediátrico Docente Provincial Eliseo Noel Caamaño, de Matanzas, por presentar dolor abdominal, heces pastosas, náuseas y vómitos desde hacía un año. Llevó tratamiento con ranitidina, omeprazol y domperidona, sin mejoría clínica. Se realizó estudio coproparasitológico en muestras de heces fecales seriadas, con la presencia del Blastocystis hominis. Se indicó tratamiento con metronidazol, sin mejoría clínica, y posteriormente se indicó como alternativa la nitazoxanida. Se evaluó a los 15 días, sin sintomatología y con negativización de las heces fecales seriadas. Resulta frecuente el desconocimiento y la poca importancia que los profesionales sanitarios muestran ante esta infestación, aunque cada vez más se confirma la participación del parásito en manifestaciones clínicas (AU).

ABSTRACT Blastocystis sp. is a frequent parasite in humans, identified in the laboratory in samples of fecal feces. The case of a 5-year-old patient is presented; he assisted the consultation of Gastroenterology in the Provincial Teaching Pediatric Hospital Eliseo Noel Caamaño in Matanzas, suffering abdominal pain, mash feces, nauseas and vomits for one year, and was treated with ranitidine, omeprazole and domperidone without clinical improvement. A coproparasitological study was carried out in serial fecal feces samples with the presence of Blastocystis hominis. Treatment with metronidazole was indicated without clinical improvement and them, as an alternative, nitazoxanide was indicated. He was evaluated at 15 days without symptoms and with negative serial fecal feces. The ignorance and the little importance that health professionals show towards this infestation are frequent, although more and more frequently it is confirmed the participation of the parasite in clinical manifestations (AU).

[Parasitosis and irritable bowel syndrome]. / Parasitosis y síndrome de intestino irritable.

Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal tract characterised by multi-factorial aetiology. In IBS physiopathology are involved diverse factors between them biological, psychosocial, and environmental components which affect the immune activation status of gut mucosa. Among these factors is recognized the intestinal parasitosis. Post-infection IBS (PI-IBS) is recognised as a subgroup of functional disorders whose symptoms onset appear after a symptomatic intestinal infection caused by microbial agents. There are few studies regarding of relationship between IBS and intestinal parasitosis in Chile. However, is has been well described a positive association between IBS and Blastocystis hominis infections, one of prevalent parasites in Chile. In other countries, is also described a relationship between IBS and amebiasis and giardiasis. Both, characterized by a common mode of transmission through water as well as contaminated food. Because the high prevalence of parasitosis in our country it is necessary to expand the association studies to clarify the strength of the parasites ethiology in IBS.

Parasites in nosocomial diarrhoea: are they underestimated?

Nosocomial diarrhoea, defined as diarrhoea occurring more than 72 h after hospital admission, is reported to account for <1% of endemic nosocomial infections and 17% of epidemic nosocomial infections. The yield of diagnoses from stool cultures in nosocomial diarrhoea is low, and information regarding the role of parasites is limited. We conducted a study to determine the responsible bacterial and parasitological pathogens from nosocomial diarrhoea cases in our 2000-bed tertiary care facility over a 16-month period. Of 226 patients, Clostridium difficile toxins A or B were present in 5.5%, giardia cysts and/or trophozoites in 4.4%, Blastocytis hominis in 4.4% and Cryptosporidium sp. in 0.5% of samples. In conclusion, parasites should be sought in nosocomial diarrhoea in endemic areas.

Extensive genetic diversity in Blastocystis hominis.

Blastocystis homonis is a common human parasite of uncertain role in human disease. Approximately equal numbers of reports implicate it and exonerate it as a pathogen. Genetic diversity in B. hominis was investigated using riboprinting to study sequence variation in the small subunit ribosomal RNA genes of 30 randomly selected isolates. Extensive sequence variation was discovered in B. hominis ribosomal RNA genes and this species consists of at least seven morphologically identical but genetically quite distinct organisms. If only a subset of the B. hominis variants have the potential to cause disease in humans this might explain the disparate findings reported. Future clinical studies must take the heterogeneity of B. hominis into account.

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.

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.