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.

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).

Parasitic profiling of Japanese quails (Coturnix japonica) on two farms with conventional production system in the Amazon region / Perfil parasitário de codornas (Coturnix japonica) em duas granjas com sistema convencional de produção na Amazônia

The health monitoring and management systems of coturniculture can be deemed to be in a developmental phase when compared to the poultry industry. Studies regarding taxonomy and parasitic biology in quails (Coturnix japonica) has not been well conducted in Brazil. Most of the information is available from the autopsy case reports, in many ways the parasitic fauna of quails is still unknown. The aim of this study was to conduct a parasitological research in quails in order to contribute to ameliorate this situation. 31 quails, which were 12 months old, were used for the study. Their carcasses and viscera were sent to the Laboratory of Entomology and Tropical Diseases, INPA, Manaus/AM. The circulatory, nervous, respiratory, digestive and reproductive systems of these were studied separately. No blood parasites were found, however, nine species of endoparasites were registered which were distributed among the classes Cestoda, Nematoda and Protozoa. The helminths were distributed in the duodenum, jejunum, ileum, cecum and oviduct. The cecum was found to be the most parasitized organ and contained a wide range of parasites having three species of protozoa and three species of nematodes. Six morphotypes of Eutrichomastix globosus were recorded, and some morphotypes were hyperparasitized with sporangia Sphaerita sp. in the cytoplasm. A large number of parasites were recorded in this study, as well as the protozoan Blastocystis hominis was first being observed for quail.(AU)

A coturnicultura conta com um monitoramento sanitário e sistemas de manejo ainda em desenvolvimento quando comparado à avicultura industrial. Pesquisas de taxonomia e biologia parasitárias em codornas (Coturnix japonica) são pouco realizadas no Brasil, sendo a maioria das informações disponíveis referentes a relatos de caso em achados de necropsia, portanto, em muitos aspectos a fauna parasitária de codornas é ainda desconhecida. Este trabalho teve por objetivo realizar uma pesquisa parasitológica em codornas em fim de postura. Para pesquisa foram disponibilizadas 31 codornas com idades de 12 meses. As carcaças e suas vísceras foram encaminhadas ao Laboratório de Entomologia e Doenças Tropicais INPA, Manaus/AM. Foram estudados separadamente os sistemas circulatórios, nervoso, respiratório, digestivo e reprodutivo. Das 31 codornas examinadas nenhuma apresentou hemoparasitos, contudo, foram registradas nove espécies de endoparasitos distribuídas entre as classes Cestoda, Nematoda e protozoários. Os helmintos distribuíam-se pelo duodeno, jejuno, íleo, cecos e oviduto. O ceco foi o órgão mais parasitado e com maior diversidade de parasitas, sendo três espécies de protozoários e três de nematóides. Foram registrados seis morfotipos de Eutrichomastix globosus, sendo que, alguns morfótipos estavam hiperparasitados com esporângio Sphaerita sp. no citoplasma. Uma grande variedade de parasitos foi registrada nesta pesquisa, bem como, o protozoário Blastocystis hominis pela primeira vez sendo descrito para codornas.(AU)

Un parásito emergente de patogenicidad controvertida, Blastocystis sp.: ¿Hay que tratar a todos los pacientes? / Blastocystis sp., an emerging parasite with controversial pathogenicity. Should all human cases be treated?

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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.

Escasa eficacia de metronidazol en la erradicación de Blastocystis hominis en pacientes sintomáticos: serie de casos y revisión sistemática de la literatura / Low efficacy of metronidazole in the eradication of Blastocystis hominis in symptomatic patients: Case series and systematic literature review

Introducción: El Blastocystis hominis (B. hominis) es un protozoo comúnmente encontrado en el tracto gastrointestinal. Existen dudas sobre su significado clínico. El metronidazol (MTZ) es el tratamiento aconsejado de primera línea. Material y métodos: Se realizó una revisión retrospectiva entre 2011 y 2012. Se seleccionaron de forma aleatoria 151 de 383 muestras positivas para B. hominis. Los criterios de inclusión fueron: clínica sugestiva, indicación de tratamiento y realización de control microbiológico. Se realizó una revisión sistemática de los estudios que evalúan el efecto de MTZ sobre la infestación por B. hominis. Resultados: Cuarenta y seis pacientes cumplían criterios de inclusión (el 64% eran mujeres; edad, 44,2±2 años). Se utilizó MTZ en 39 pacientes, de los cuales 31 obtuvieron respuesta clínica (79,5%) pero solo 15 respuesta microbiológica (48,4%). No se apreció una relación dosisefecto. Veinte pacientes sin respuesta microbiológica inicial recibieron una segunda tanda de tratamiento (MTZ, cotrimoxazol, paramomicina, otros), con una respuesta microbiológica del 70%. De forma global, se consiguió la curación de B. hominis en un 72% (IC95%: 57-83%). De 54 tratamientos asociados a respuesta clínica, se produjo respuesta microbiológica en 31 (57%); mientras que de los 12 que se siguieron de ausencia de respuesta clínica solo se observó la curación microbiológica en 2 (17%) (p = 0,022). La tasa de erradicación en la revisión sistemática osciló entre 0 y 100%. Conclusiones: Parece existir relación entre la respuesta clínica y microbiológica al tratamiento de B. hominis. En nuestro entorno geográfico la respuesta microbiológica al tratamiento con MTZ es insuficiente. La revisión sistemática muestra que la respuesta a MTZ es muy variable (AU)

Introduction: Blastocystis hominis (B. hominis) is a protozoan commonly found in the gastrointestinal tract. There are doubts about its clinical significance. Metronidazole (MTZ) is the recommended first-line treatment. Materials and methods: A retrospective review was carried out between 2011 and 2012. A total of 151 samples were randomly selected from 383 samples positive for B. hominis. Inclusion criteria were: suggestive symptoms, treatment indication and microbiological follow-up. A systematic review was performed of all studies that evaluated the effect of MTZ on B. hominis infection. Results: Forty-six patients met the inclusion criteria (64% women; age, 44.2±2 years). MTZ was used in 39 patients, 31 of whom obtained a clinical response (79.5%) but only 15 a microbiological response (48.4%). No dose-effect relationship was observed. Twenty patients with no initial microbiological response received a second round of treatment (MTZ, cotrimoxazole, paramomycin, others), with a microbiological response in 70%. Overall, B. hominis was cured in 72% (95% CI: 57%-83%). Of 54 treatments associated with a clinical response, a microbiological response occurred in 31 (57%), while in the remaining 12 with no clinical response, microbiological cure was observed in only 2 (17%) (P = .022). The eradication rate in the systematic review varied between 0% and 100%. Conclusions: There seems to be a relationship between the clinical and microbiological response to B. hominis treatment. The microbiological response to MTZ treatment is insufficient in our geographical setting. The systematic review shows that the response to MTZ is very variable (AU)

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.

[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.

Parasitosis y síndrome de intestino irritable / Parasitosis and irritable bowel syndrome

El síndrome de intestino irritable (SII) es un trastorno funcional digestivo de etiología multifactorial. En su fisiopatología se describen diversos factores, tanto biológicos, como psicológicos y ambientales, que afectan el estado de activación de células inmunes en la mucosa intestinal. Entre los factores ambientales se incluye la presencia de alguna parasitosis intestinal. El síndrome de intestino irritable post-infeccioso (SII-PI) es reconocido como un subgrupo de estos trastornos, cuya aparición de los síntomas es posterior a una infección intestinal provocada por agentes microbianos. A pesar de que en Chile hay pocos estudios respecto a la relación entre SII y parasitosis intestinal, se ha descrito la existencia de una asociación positiva entre SII e infecciones por Blastocistis hominis, uno de los parásitos prevalentes en Chile. En otros países, se ha descrito además una relación entre SII, amebiasis y giardiasis. Por la alta prevalencia de parasitosis en nuestro país, existe la necesidad de ampliar los estudios para clarificar la fuerza de la asociación entre parasitosis y SII.

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.

Stress exacerbates infectivity and pathogenicity of Blastocystis hominis: in vitro and in vivo evidences.

BACKGROUND: Stress alters the oxidant-antioxidant state and immune cell responses which disrupts its function to combat infection. Blastocystis hominis, a common intestinal protozoan has been reported to be opportunistic in immunocompromised patients namely cancer. B. hominis infectivity in other altered immune system conditions especially stress is unknown. We aimed to demonstrate the stress effects towards the susceptibility and pathogenicity of B. hominis infection. METHODS/FINDINGS: Three-week-old Wistar rats were divided into four groups: (a)control; (b)stress-induced; (c)B. hominis infected; (d)stress-induced with B. hominis infection; (n = 20 respectively). Stress was induced for an hour daily (30 days) using a Belly Dancer Shaker. Weight gain was monitored, stool samples were collected for B. hominis screening and blood for the determination of differential count, levels of immunoglobulin, oxidative damage, and peripheral blood mononuclear cell (PBMC) proliferation upon induction with solubilized antigen of B. hominis (Blasto-Ag). Group (b) exhibited the highest level of weight gain. Group (d) had higher levels of parasite cyst count in stools, serum IgE, oxidized protein and lipid compared to the group (c). Levels of monocyte and antioxidant in group (d) were decreased and their PBMCs showed highest inhibition of proliferation level when exposed to Blasto-Ag. Monocyte level in Group (b) showed insignificant difference compared to group (a) but was significantly lower compared to group (c). Antioxidant levels in group (c) were generally lower compared to group (a) and (b). Inhibition level exhibited by Blasto-Ag treated PBMCs of group (c) was higher compared to group (a) and (b). CONCLUSION: The pathogenicity and augmentation of B. hominis infection is enhanced when stress is present. Lifestyles today are becoming increasingly stressed and the present findings suggest that the parasite which has been reported to be one of the most common organisms seen in stool surveys, namely in developing countries, may tend to be more pathogenic in stressful situations.

[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.

Epidemiological survey of the prevalence of intestinal parasites among schoolchildren in Sari, northern Iran.

Parasitic infection is highly prevalent throughout the developing countries of the world. Research on the prevalence of intestinal parasitic infections in various geographic regions is a prerequisite for the development of appropriate control strategies. A cross-sectional study was conducted to determine the prevalence of intestinal parasitic infections among schoolchildren in public primary and secondary schools in the urban areas of Sari, Mazandaran province, northern Iran. The study was conducted from November 2009 to June 2010. A total of 1100 stool samples from 607 males and 493 females aged 7-14 years were examined by direct wet mounting, formalin-ether concentration, and Ziehl-Neelsen and trichrome permanent staining methods. A parental questionnaire for common risk factors was completed for each participant. Mono- or poly-parasitism was detected in 367 (33.3%) of the children (32.6% of males and 34.2% of females). Various species of protozoan or helminth infections were detected: Blastocystis hominis seemed to be the most prevalent parasite (13.5%) followed by Giardia lamblia (10.6%), Entamoeba coli (7.2%), Endolimax nana (1.5%), Enterobius vermicularis (2.2%), Trichostrongylus sp. (2.1%) and Strongyloides stercoralis (1.6%). The prevalence of intestinal parasite infections in females was slightly higher than in males, though without a statistically significant difference (p=0.56). No age association was detected, and a slightly lower positive association with increasing age was observed (p=0.33). A significant association was observed with parents' educational level, household income and practice of hand washing before meals (p<0.01). Although paediatric pathogenic intestinal parasite infections are not more prevalent in this geographical area than in other regions, improvements in personal hygienic conditions and behavioural characteristics is important to completely control parasitic infections in schoolchildren in northern Iran.

Infections of Blastocystis hominis and microsporidia in cancer patients: are they opportunistic?

Chemotherapy can cause immunosuppression, which may trigger latent intestinal parasitic infections in stools to emerge. This study investigated whether intestinal parasites can emerge as opportunistic infections in breast and colorectal cancer patients (n=46 and n=15, respectively) undergoing chemotherapy treatment. Breast cancer patients were receiving a 5-fluorouracil/epirubicin/cyclophosphamide (FEC) regimen (6 chemotherapy cycles), and colorectal cancer patients were receiving either an oxaliplatin/5-fluorouracil/folinic acid (FOLFOX) regimen (12 cycles) or a 5-fluorouracil/folinic acid (Mayo) regimen (6 cycles). Patients had Blastocystis hominis and microsporidia infections that were only present during the intermediate chemotherapy cycles. Thus, cancer patients undergoing chemotherapy should be screened repeatedly for intestinal parasites, namely B. hominis and microsporidia, as they may reduce the efficacy of chemotherapy treatments.

Artritis reactiva por Blastocistys hominis / No disponible

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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.

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.

In vitro culture of blastocystis hominis in three liquid media and its usefulness in the diagnosis of blastocystosis.

BACKGROUND: Blastocystis hominis is a common protozoan in the human intestinal tract and can cause the so-called blastocystosis characterized by diarrhea. To date, its identification has depended on the discovery of vacuolar, granular, amoebic, or cystic forms in stool samples using wet mount smears, iodine staining, trichrome staining, or iron hematoxylin staining. The permanent staining methods provide more positive findings. However, mercuric chloride (HgCl(2))-based polyvinyl alcohol (PVA) and Schaudinn fixative are potentially toxic and dangerous to laboratory personnel and, as hazardous chemicals, present problems with disposal. METHODS: To determine whether in vitro culture could be an environmentally safe alternative, the culture growth of B. hominis in three commercially available liquid media (RPMI 1640, 199 Medium, and Dulbecco's modified Eagle's medium (DMEM)) were observed and compared. The sensitivity and specificity of these culture methods to identify B. hominis were compared with those of existing methods used clinically. RESULTS: Conditions for the anaerobic culture of B. hominis in these media were determined as follows: total inoculum sizes no less than 10(5) cells; pH values ranging from 7.0 to 7.5; concentrations of calf or horse serum ranging from 10% to 30% (vol/vol); basic antibiotics added; peaking times at days 3, 6, and 9 (pH 7.5) or days 4 and 8 (or 9) (pH 7.0) at 37°C. No significant differences were noted in multiplication or generation times for the cultivation of B. hominis (p>0.05). In 56 of 398 positive cases, the short-term in vitro culture method achieved the best performance with regard to sensitivity and specificity of the five studied methods. CONCLUSIONS: With the advantages of environmental safety, convenience in preparation and storage, facility in morphologic discrimination, and outstanding performance in terms of sensitivity and specificity, the in vitro culture method could be applied to identify B. hominis for both clinical diagnosis and field study purposes.

A study on Blastocystis hominis in food-handlers: diagnosis and potential pathogenicity.

Proper diagnosis of Blastocystis hominis in not performed routinely in medical laboratories of developing countries; consequently clinical significance of this common intestinal protozoon is liable to remain unsettled. Food-handlers are more prone to get and transmit this feco-oral infection. This work compared the sensitivity of direct diagnostic methods to detect B. hominis in stool, estimate the true prevalence among food-handlers in Sirte-Libya, to clarify the association between the parasite and gastrointestinal symptoms and the response to specific treatment. A total of 400 male food-handlers aged 18-50 year were included. Each was subjected to clinical questionnaire and 3 stool examinations by different methods. The results showed high prevalence of B. hominis in food-handlers (35.5%). Short- term in vitro culture (on Boeck and Derbholav's medium) was the most sensitive method for detection of B. hominis (35.5%), followed by permanent Trichrome-stained smear (27.5%); saline-sedimentation concentrated smear (21%) and direct iodine smear (14%). Of 108 cases having B. hominis alone, 68.5% were symptomatic. Diarrhea was the most frequent symptom (75.6%), followed by abdominal pain (66.2%) and flatulence (43.2%). Fecal parasite-load was significantly higher in symptomatic cases than asymptomatic; parasite and symptoms disappeared after metronidazole treatment. So, culture should be used on routine basis to detect B. hominis which should be considered pathogenic particularly when present alone in large numbers in symptomatic patients.