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A

M

OE

B

A

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General Characteristics: Unicellular organisms

Possess Pseudopodia as organ for locomotion andprocurement of food

Holozoic All are strictly parasitic

Most inhabits the Large Intestine (Cecum)

Commensals except for Entamoeba histolytica

Most have Trophozoite and Cystic stages

Multiplies by binary fission

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Structure of the parasite:

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TROPHOZOITE VS CYSTIC Stages

Motile Feeding stage Most are irregular in shape Contains one nucleus Frequently found in diarrhealand liquid stools Easily disintegrated uponstanding Destroyed by Iodine

Non-motile Non-feeding stage Infective Stage Presence of chromatoidal barsand glycogen vacuoles Smooth and rounded in shape Contains more than one nuclei Frequently recovered in formedstools

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A. Entamoeba

E. gingivalis E. coli E. histolytica

B. Endolimax E. nana

C. Iodamoeba I. buetschlii

Differentiated by their nuclearstructures.

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Entamoeba gingivalis First parasitic amoeba to be described

Atrial Amoeba

Habitat: Buccal Cavity

Demostration of trophozoite in materials or scrapingsfrom the gingival margin of the gums, between teeth ordentures, and the soft tartar of the teeth

NO Cystic Stage

MOT: via droplet spray i.e. kissing and sharing of utensils

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Entamoeba gingivalis TROPHOZOITE:

5-35u in diameter

Exhibits a definite zone of demarcation between theclear ectoplasm and the more granular endoplasm

Endoplasm contains food vacuoles with host leukocytesand epithelial cells, at times bacteria and rarely, RBC

Nucleus is nearly spherical with karyosome near its center

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Entamoeba gingivalis TROPHOZOITE:

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Entamoeba coli Worldwide in distribution

Non-pathogenic intestinal amoeba

Habitat: Large Intestine (Cecum) MOT: ingestion of infective cyst from contaminated foodand drinks

Diagnostic Stage: Trophozoite and Cyst stages

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Entamoeba coli CYST: 10-33u in diameter

Nucleus contains eccentrically located karyosome

May contain 1-8 nuclei depending on maturity

Chromatoidal bars with splintered ends and glycogenvacuoles can be observed in the endoplasm

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Entamoeba coli CYST:

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Entamoeba coli TROPHOZOITE: 15-50u in diameter

Nucleus contains eccentrically located karyosome

Endoplasm is highly vacuolated which may containbacteria and yeasts, no RBC

Ectoplasm is not well demarcated from the endoplasm

In wet mounts, movement is sluggish with multiplepseudopods thrusted at the same time

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Entamoeba coli TROPHOZOITE:

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Entamoeba histolytica Worldwide in distribution

The only pathogenic and tissue invading amoeba

Causes Amoebiasis which can be limited to the gutalone or have extraintestinal invasions

MOT: ingestion of infective cyst from contaminated foodand drinks

Diagnostic Stage: Trophozoite and Cyst stages

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Entamoeba histolytica

CYST:

10-20u in diameter

Nucleus is centrally located

May contain 1-4 nuclei depending upon maturity

Cytoplasmic inclusions such as glycogen vacuoles andchromatoidal bars which have rounded ends (cigar-shaped) may be present

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Entamoeba histolytica

CYST:

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Entamoeba histolyticaTROPHOZOITE: 10-60u in diameter

Nucleus is centrally located

Has a finely granular endoplasm that is clearlydifferentiated from the ectoplasm

Endoplasm may contain ingested RBC

In wet mounts, it exhibits progressive unidirectionalmovement with single pseudopod thrusted out in anexplosive manner

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Entamoeba histolytica TROPHOZOITE:

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Entamoeba histolytica

PATHOGENECITY:

Intestinal Amoebiasis

Hepatic Amoebiasis or Extraintestinal Lesions

- Flask-shaped ulcers

Amoebic Dysentery

- Stool has a gelatinous mixture of blood mucus andfeces.

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Laboratory DiagnosisI. Intestinal Amoebiasis

1. Stool Examination

- Examined within 30 minutes after voiding

- Wet mounts with NSS

- Iodine-Hematoxylin or Trichrome Stains

- Diarrheic/Liquid Stools: Trophozoite

- Formed Stools: Cyst

2. Sigmoidoscopy

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Laboratory DiagnosisII. Hepatic Amoebiasis/ Extraintestinal Lesions

1. Establish presence of Intestinal Amoebiasis

2. Increased WBC

3. Increased Liver Enzymes

4. Needle Biopsy of Abscess

5. Serologic Tests