Differences in Clinical Significance and Morphologic Features ofBlastocystissp Subtype 3

Abstract

Blastocystis is a polymorphic intestinal parasite that is common in humans. A total of 51 asymptomatic and symptomatic patients positive for Blastocystis only were included in the study. Symptoms were mainly nonspecific gastrointestinal symptoms. Blastocystis isolates were xenically cultured and subtyped. Blastocystis species subtype 3 was the predominant subtype. Intrasubtype differences (vacuolar/amoeboid presence) in subtype 3 morphotypes were observed in 32 asymptomatic and symptomatic subtype 3 cases and could possibly be related to Blastocystis pathogenic potential. Diverse morphologic features (vacuolar transiting to amoeboid), probably reflecting the progression from an asymptomatic to a symptomatic state, were observed in an asymptomatic subtype 3 carrier who later had symptoms. Searching for amoeboid forms might be helpful to presumptively screen symptomatic patients with subtype 3 or to follow up an asymptomatic subtype 3 carrier in case symptoms become evident before antiprotozoal treatment was attempted. Further studies on the roles of morphologic features and variation within Blastocystis species subtypes as predictors of symptoms are encouraged.

Blastocystis hominis, un gran desconocido

“…Algunos autores 7 han sugerido que es patógeno cuando está presente en gran número (más de cinco organismos por campo con objetivo [100×] de inmersión), sin embargo, otros autores no encuentran asociación entre concentración parasitaria y presencia de síntomas. Recientemente se han descrito varios subtipos genéticamente diferentes 2 mediante el análisis de la secuencia del ARN ribosómico, y además se han descrito varios morfotipos 8,9 . La heterogeneidad de las cepas, acompañada por la virulencia variable, puede explicar las diferencias en patogenicidad.…”

“…Entre los subtipos aislados en humanos, el más frecuente es el subtipo 3, pero también están presentes con relativa frecuencia los subtipos 1 y 6 8 . En España se ha encontrado sobre todo el subtipo 4 23 .…”

“…El B. hominis ha sido relacionado con las enfermedades diarreicas en varias poblaciones del mundo 7,8 ; sin embargo, ninguno de nuestros pacientes presentó diarrea aguda, tan solo un 26,6% presentaban alteraciones del ritmo, con 1-4 deposiciones al día, explosivas y acompañadas de gases y parte líquida al final de la evacuación. Por el contrario, la mayoría de nuestros pacientes presentaban dolor abdominal crónico (Fig.…”

Recent Developments in Blastocystis Research

“…It seems equally likely that the treatment perturbs the intestinal flora, indirectly making it a poor or unsuitable habitat for Blastocystis. The second problem is that all common subtypes and certain others have been linked with symptoms, which seems an unlikely situation (DogrumanAl et al, 2008;Domínguez-Márquez et al, 2009;Jones et al, 2009;Stensvold et al, 2011a;Vassalos et al, 2010;Vogelberg et al, 2010).…”

Blastocystis Hominis: a Mysterious and Commonly Disregarded Parasite

“…Zierdt has suggested Gram staining of unfixed smears to be undertaken for their identification, since these forms undergo lysis when exposed to air, while leukocytes remain intact [4,9]. It is more commonly present in individuals with symptoms of digestive tract infections and in cultures, indicating the pathogenic potential of this form of B. hominis [1,21].…”