Ultrastructural changes during in vitro encystment ofBlastocystis hominis

Suresh, K.; Howe, J.; Chong, Suet Yen; Ng, G. C.; Ho, L. C.; Loh, Ann; Ramachandran, N. P.; Yap, E. H.; Singh, Mulkit

doi:10.1007/bf02351875

Cited by 31 publications

(46 citation statements)

References 22 publications

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“…Experimental infectivity studies of BALB/c mice, Wistar rats, and a variety of bird species with the cyst form indicate that this form is undoubtedly the transmissible form of the parasite. The formation of in vitro-derived cysts by the incubation of vacuolar forms in encystation medium was reported previously (240,241,244,282). These "cysts" appear to be curiously similar to the classical granular forms, and the granules within the central vacuole were reported to be reproductive in nature (240,241,243).…”

Section: Morphological Formssupporting

confidence: 52%

“…The formation of in vitro-derived cysts by the incubation of vacuolar forms in encystation medium was reported previously (240,241,244,282). These "cysts" appear to be curiously similar to the classical granular forms, and the granules within the central vacuole were reported to be reproductive in nature (240,241,243). It is likely that these are artifacts of culture induced by the encystation medium, as they bear no morphological similarity to the fecal cyst.…”

Section: Morphological Formsmentioning

confidence: 67%

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New Insights on Classification, Identification, and Clinical Relevance of Blastocystis spp

Tan¹

2008

Clin Microbiol Rev

624

715

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SUMMARY Blastocystis is an unusual enteric protozoan parasite of humans and many animals. It has a worldwide distribution and is often the most commonly isolated organism in parasitological surveys. The parasite has been described since the early 1900s, but only in the last decade or so have there been significant advances in our understanding of Blastocystis biology. However, the pleomorphic nature of the parasite and the lack of standardization in techniques have led to confusion and, in some cases, misinterpretation of data. This has hindered laboratory diagnosis and efforts to understand its mode of reproduction, life cycle, prevalence, and pathogenesis. Accumulating epidemiological, in vivo, and in vitro data strongly suggest that Blastocystis is a pathogen. Many genotypes exist in nature, and recent observations indicate that humans are, in reality, hosts to numerous zoonotic genotypes. Such genetic diversity has led to a suggestion that previously conflicting observations on the pathogenesis of Blastocystis are due to pathogenic and nonpathogenic genotypes. Recent epidemiological, animal infection, and in vitro host-Blastocystis interaction studies suggest that this may indeed be the case. This review focuses on such recent advances and also provides updates on laboratory and clinical aspects of Blastocystis spp.

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Section: Morphological Formssupporting

confidence: 52%

Section: Morphological Formsmentioning

confidence: 67%

New Insights on Classification, Identification, and Clinical Relevance of Blastocystis spp

Tan¹

2008

Clin Microbiol Rev

624

715

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“…The amoeboid form of B. hominis has been reported infrequently, and its morphological descriptions have yielded conflicting and confusing reports particularly on the presence of cell membrane, surface coat, central vacuole, and organelles (Zierdt 1973(Zierdt , 1991Zierdt and Tan 1976;McClure et al 1980;Dunn et al 1989;Suresh et al 1994b;Tan et al 2001). In the present study, two types of amoeboid forms were found, one contained a large central vacuole completely filled up with tiny electron-dense granules, and the other did not have a large central vacuole, but instead showed multiple small vacuoles in the cytoplasm.…”

Section: Discussionmentioning

confidence: 95%

Predominance of amoeboid forms of Blastocystis hominis in isolates from symptomatic patients

Tan

2005

Parasitol Res

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Blastocystis hominis is one of the most common human parasites that inhabit the intestinal tract. Conflicting reports continue to exist regarding the existence and the functional role of the amoeboid forms in the life cycle of the parasite. The present study investigates the presence of these forms in 20 isolates obtained from ten symptomatic and asymptomatic patients respectively. A total of 10,000 parasite cells per ml from each isolate were inoculated into three culture tubes each containing 3 ml of Jones' medium supplemented with 10% horse serum, incubated at 37 degrees C. The contents were examined daily for 10 days. Irregular and polymorphic amoeboid forms with multiple extended pseudopodia were observed in all isolates from symptomatic patients, while none of the isolates from asymptomatic patients showed the presence of the amoeboid forms. The amoeboid forms were initially noted on day 2 and the percentages increased from 2% to 28%, with peak percentages from day 3 to day 6. Transmission electron microscopy revealed two types of amoeboid forms; one containing a large central vacuole completely filled with tiny electron-dense granules, and the other which revealed multiple small vacuoles within the central body. The cytoplasm contained strands of electron-dense granules resembling rough endoplasmatic reticulum, which is suggestive of active protein synthesis. The surface coat of the amoeboid form surrounding the parasite showed uneven thickness. Acridine orange stained the central body yellow and the periphery orange, indicating activity at the level of nucleic acids. The amoeboid form could either be an indicator of pathogenicity of B. hominis, or the form likely to contribute to pathogenicity and be responsible for the symptoms seen in patients.

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“…A number of con¯icting de®nitions have been presented in the literature . Several studies suggest that this form extends pseudopodia and feeds on bacteria (Zierdt, 1973;Dunn et al, 1989;Suresh et al, 1994;Singh et al, 1995). A central vacuole was not noted, and the cells varied in diameter (approximately 3±8 mm).…”

Section: Amoeboid Formmentioning

confidence: 94%