Polypeptides associated with in vitro cyst formation of Blastocystis hominis.

The objective of this study was to characterize the polypeptides associated with cysts of Blastocystis hominis. This form is believed to be infective and plays a role in parasite resistance to anti-B. hominis drugs currently used for treatment of Blastocystis associated diarrhea. Cysts were induced through in vitro culture of the parasite in complete medium supplemented with bacterial extract with trypticase, metronidazole or doxycycline. SDS-PAGE analysis showed almost similar polypeptide patterns of parasite extracts obtained from in vitro cultured parasites before and after exposure with the three supplements. Polypeptide bands at 76, 58.5, 48, 45, 40, 38, 32, 25 and 22 kDa were constantly seen in all antigenic preparations and no specific cyst-associated polypeptide was present. However, on immunoblot analysis, 3 out of 16 blastocystosis human sera identified a cyst-associated polypeptide at 60 kDa in all parasite extracts prepared from cultures with the three supplements. In addition, there were associated morphological changes detected in these parasites stained with acridine orange and observed under fluorescence microscopy. Metronidazole induced cyst forms (reddish cells) as early as 12 hours post-exposure; more cyst production (with stronger immunoblot bands) occurred after 24 hours exposure. However, cysts rupture with release and destruction of B. hominis daughters cells occurred after 48 hours exposure. Doxycycline induced less cyst-like forms at 24 hours (weaker 60 kDa band) and less destruction of the cysts (60 kDa band still present at 72 hours post exposure). Bacterial extract and trypticase also induced cysts at 12 hours with increasing numbers up to 72 hours exposure (corresponding increase in intensity of 60 kDa band from samples harvested at 12 to 72 hours post exposure) without any sign of deleterious effect on the parasite.

Blastocystis hominis--an emerging cause of diarrhoea in renal transplant recipients.

Blastocystis hominis is an intestinal protozoan that is emerging as an important cause of diarrhea in the immunosuppressed population. We report two cases of diarrhea caused by this organism in renal transplant recipients. The infection was diagnosed promptly by careful stool examination and treated successfully with metronidazole. These case report highlights the fact that unusual parasites like Blastocystis hominis should be looked for and treated in cases of diarrhea occurring in renal transplant recipients. This reduces the rate of post-transplant morbidity and mortality.

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

Blastocystis hominis: un parásito frecuente en Chile / Blastocystis hominis: a frequent parasite in Chile

Se seleccionaron trabajos nacionales y extranjeros publicados para responder varias preguntas acerca de B. hominis. Se consideraron variables como edad, sexo, diagnóstico y tratamiento. Estos trabajos apoyan el rol patógeno de B. hominis. Sus manifestaciones más frecuentes son diarrea, dolor abdominal y, con menor frecuencia, meteorismo, anorexia náuseas y vómitos. Como convención entre laboratorios, se considera positivo un examen con visualización de al menos cinco parásitos por campo (40x). Metronidazol es el fármaco más efectivo para erradicar B. hominis. En los estudios revisados se reportó altas prevalencias nacionales con cifras entre 21,3 y 63,2 por ciento. Clínicos y científicos sugieren mayores estudios y vigilancia epidemiológica

Blastocystis hominis: patógeno o comensal? revisión de la evidencia / Blastocystis hominis: pathogen or commensal? evidence reviewed

Blastocystis hominis es un microorganismo común que habita el intestino humano y cuya clasificación taxonómica y papel patogénico han estado en disputa. Recientemente en base a estudios genéticos, se encontró relacionado estrechamente con el grupo que incluye algas cafés, algas café-doradas y diatomeas. Asimismo, se ha sugerido que la variabilidad genética detectada entre especimenes podría indicar la presencia de cepas o especies diferentes y con un potencial patogénico distinto. A continuación se revisa la evidencia a favor y en contra de la patogenicidad de B. hominis