Blastocystis hominis and e. polecki

Entamoeba polecki(an intestinal amoeba)

&Blastocytis hominis(a pseudoparasite)

Prepared by:Aguilar, Princess Alen I.

E. polecki• Superkingdom: Eukaryotae• Kingdom: Animalia• Subkingdom: Protozoa• Phylum: Sarcomasigophora• Subphylum: Sarcodina• Superclass: Rhizopoda• Class: Lobosa• Subclass: Gymnamoeba• Order: Amoebida• Suborder: Tubulina• Family: Entamoebidae• Genus: Entamoeba• Species: Polecki

History

• Entamoeba Polecki was first identified in 1912 in Czechoslovakia by Von Prowazek in the stool samples of two students from Kampuchea.

• E. Polecki was repeatedly found in pig feces, but no other human cases were reported until 1949

• Maybe asymptomatic or mistaken as E. histolytica

E. polecki-General Characteristics

Intestinal parasite of pigs and monkeysFound occasionally in humanCommon intestinal parasite in parts of Papua

New Guinea (19%)Pig-to-human transmissionHuman-to-human transmission

L I F E C Y C L E

Diagnostic stage

• Cyst and trophozoite• Cyst’s usual size, 5-11 µm• Trophozoites’ usual size, 10-12 µm

which is usually round

Genus Entamoeba

• Almost all of entamoeba spp are morphologically identical and of the size range, BUT CAN BE DIFFIRENTIATED BY isoenzyme analysis, restriction fragment length polymorphism and typing with monoclonal antibodies.

PATHOGENESIS

• KNOWN AS NON-PATHOGENIC

• Diarrhea• Isoenzyme studies of a number of isolates- E. polecki

vs E. dispar • Isoenzyme characterization

(trophozoites)-E. polecki vs. E. chattoni

Laboratory Diagnosis(specimen is stool)

Stage & preparation CharacteristicsTrophozoites, unstained Not characteristic

Trophozoites, stained Suggestive: nucleus with minute central karyosome, w/ peripheral chromatin evenly distributed or massed at one or both poles; ingested bacteria

Cysts, unstained Suggestive: uniform mononuclear condition

Cysts, stained (iodine) Suggestive: mononucleated cysts; large central karyosomes w/ evenly distributed peripheral chromatin or massed at one or both polesDiagnostic: inclusion masses, chromatoidal bars w/ angular or pointed ends.

Cyst of E. polecki in a wet mountStained with iodine. Notice the numerous chromatoid bodies (arrows).

Cysts of E. polecki stained with trichrome. Notice the large nucleus with a pleomorphic karyosome and numerous variably-shaped chromatoid bodies.

Trophozoites of E. polecki stained with trichromeThe single nucleus is often distorted and irregularly-shaped, with a small to minute centrally-located karyosome. Peripheral chromatin is usually delicate and uniform. The cytoplasm is often vacuolated with a hyaline border. Blunt pseudopodia may be seen.

Treatment

• Except diloxanide furoate (Furamide) and metronidazole (Flagyl)

• Pilot by Salaki and coworkers (1979)• 750mg 3x/ daily for 10 days with 500mg 3x/

daily for 10 days• 750mg 3x/ daily for 5,7, or 10 days

Blastocystis hominis• Kingdom: Protista• Subkingdom: Protozoa• Phylum: Sarcomastigophora• Subphylum: Sarcodina• Superclass: Rhizopoda• Class: Lobosea• Subclass: Gymnamoeba• Order: Amoebida• Suborder: Blastocystina• Genus: Blastocystis• Species: Hominis

B. Hominis-General Characteristics

• Pseudoparasite hence non -pathogenic• Generally consider a nonpathogenic yeast in the past• Some maintain that it has protozoan affinities,

although on the basis of rRNA sequencing, its phylogenetic affinities are less clear (Johnsons et al., 1989)

• Inhabitant of the human intestinal tract• Binary fission• Having pseudopod extension and retraction

LIFECYCLE

Acquiring of B. hominis

• Accidentally swallowing Blastocystis 'hominis' picked up from surfaces contaminated with feces from an infected person or animal.

• Drinking water or using ice made from contaminated sources

• Swallowing recreational water contaminated with Blastocystis 'hominis'.

• Traveling to countries where Blastocystosis is common and being exposed to the parasite as described in the bullets above.

Morphology

• The classic form that is usually seen in stool specimens varies in size from 6 - 40mm and is characterized by a large membrane bound central body which occupies 90% of the cell. It has no internal nuclear structure and a rim of peripheral granules the function of which is not known.

P a t h o g e n e s i s

• Generally when seen in stool, we do not give significance BUT the pathogenic potential of Blastocystis may very well depend on subtype.

• 95% of humans colonized by Blastocystis have one of the following subtypes: ST1, ST2, ST3, ST4 hence acknowledge as pathogen

• Organism has been associated with nausea, fever, vomiting, diarrhea and abdominal pain.

Consider as one of the org’s with uncertain taxonomic status

• Found a DNA-based home w/ highly diverse protistan group-the stramenophiles (a vast array of organisms including brown algae, water molds, and diatom)

• Found in the immunocompetent persons but commonly in patients with GIT disorders

Laboratory Diagnosis

Type of preparation Characterization

Iodine preparations The peripheral layer is light yellowish and the nuclei position is clearly indicated

Permanent stains Central material has intense stain, stain lightly or may not stain at all; the nuclei is dark, and embedded

PCR and culture use/Fields’ and Giemsa

Accurate diagnosis is warranted if this was the first choice

SPECIMEN: STOOL

Iodine stained

Trichome stained

Romanowski’s stainCyst of Blastocystis hominis demonstrating its vacuolated cell wall.

Giemsa stainedCyst-forming microbes of varying sizes observed in the feces

Papanicolaou stainedCyst-forming microbes of varying sizes observed in the feces

Treatment

• Several said that it is still unidentified.• no single drug or no particular diet appears to be

capable of eradicating Blastocystis • Chemotherapeutic drug Metronidazole- most widely

used treatment option

• Nitazoxanide- recent study, has been with much more

positive effects, with 86% of those treated with the drug

effectively cured

THANK YOU FOR

LISTENING!