In vitro cultivation for detection and phenotypic study of blastocystis spp. in stool samples

ABSTRACT

Blastocystis spp. is an unusual enteric parasite of human and many animals. Recent observations indicate that humans are hosts to different pathogenic and non-pathogenic genotypes, many of which are zoonotic. The aim of the present study is to determine the usefulness of short term in vitro cultivation of stool samples in detection of Blastocystis spp. over routine techniques. Also to study the different morphological forms and reproductive modes from longer term cultures and stool samples. One hundred stool samples from symptomatic patients were processed for short term in vitro cultivation using Jones'medium. Direct microscopy of culture samples was compared to that of wet preparation and modified trichrome staining of stool samples. Longer term cultivation of Blastocystis positive samples was conducted to study different morphological forms and reproductive modes of the parasite using direct microscopy of stained and unstained samples, ocular micrometer, phase contrast microscopy [PCM] and scanning electron microscopy [SEM]. Short term in vitro cultivation of stool samples significantly increased the recovery of Blastocystis spp. over examination of wet preparation by 42.86% [p=0.0001] and over permanent staining using modified trichrome stain by 28.57% [p=0.000 1]. Examination of stained and unstained samples from stools and longer term cultures of positive samples revealed five different morphological forms; vacuolar, granular and amoeboid, multivacuolar and cyst forms. As regards the reproductive modes of Blastocystis, the present study identified five modes of reproduction from stool and culture samples binary fission, multiple fission, budding, endodyogeny and plasmotomy. Schizont-like cells were also seen in some stool and culture samples. Short term in vitro culture of stool samples is a highly recommended diagnostic tool for Blastocystis spp. Infection. Long term culture is a useful tool to study different morphological forms and reproductive modes. More studies are required to verif' some reproductive modes of the parasite