Entamoeba fam

Entamoeba histolytica

A protozoan parasite that can cause intestinal and extraintestinal amoebiasis; discovered by Fedor Losch in 1875.

Morphology of Entamoeba histolytica cyst

Spherical (10-20 µm), 1-4 nuclei, fine granular cytoplasm, elongated chromatoid bars (cigar-shaped).

Morphology of Entamoeba histolytica trophozoite

Irregular (12-60 µm), progressive motility, finely granular cytoplasm, ingested RBCs.

Pathogenesis of Entamoeba histolytica

Asymptomatic in 90% of cases or can cause intestinal and extraintestinal amoebiasis.

Amoebic ulcers

Flask-shaped ulcers caused by Entamoeba histolytica, commonly found in the caecum and sigmoidorectal region.

Symptoms of dysentery due to Entamoeba histolytica

Brownish-black stool, blood-streaked mucus, and Charcot-Leyden crystals.

Liver abscess associated with Entamoeba histolytica

Characterized by thick 'anchovy sauce pus' and potential jaundice if pressing on the biliary tract.

Infective form of Entamoeba histolytica

Mature quadrinucleate cyst.

Definitive host of Entamoeba histolytica

Humans.

Mode of transmission (MOT) for Entamoeba histolytica

Ingestion of cysts via contaminated food or water.

Diagnosis method for Entamoeba histolytica

Stool exam is the gold standard, using concentration techniques.

Culture media for Entamoeba histolytica

Boeck/Drbohlav, Balamuth’s, Robinson & Inoki media.

Serodiagnosis methods for Entamoeba histolytica

ELISA, Latex agglutination, Indirect hemagglutination.

First-line treatment for invasive amoebiasis caused by Entamoeba histolytica

Metronidazole.

Treatment for asymptomatic carriers of Entamoeba histolytica

Diloxanide furoate.

Entamoeba dispar

Morphologically identical to E. histolytica but non-invasive, more common in homosexual men.

Morphology of Entamoeba dispar trophozoite

Progressive motility, fine beaded nucleus, small central karyosome.

Entamoeba hartmanni

A nonpathogenic 'small race' of E. histolytica.

Morphology of Entamoeba hartmanni trophozoite

Non-progressive (3-12 µm) with finely granular cytoplasm.

Morphology of Entamoeba hartmanni cyst

(4-10 µm) with 1-4 nuclei, elongated chromatoid bar (rice grain-shaped).

Entamoeba coli

A nonpathogenic commensal intestinal amoeba.

Morphology of Entamoeba coli trophozoite

(15-50 µm) with non-progressive, coarsely granular cytoplasm and large eccentric nucleus.

Morphology of Entamoeba coli cyst

(13-30 µm) with 1-8 nuclei, irregular coarse chromatoid bars.

Entamoeba gingivalis

Only has a trophozoite stage, lives on teeth, and can be opportunistic in immunocompromised hosts.

Link of Entamoeba gingivalis

Possible link to periodontitis.

Morphology of Endolimax nana trophozoite

(8-10 µm) with non-progressive, granular cytoplasm and large blot-like nucleus.

Morphology of Endolimax nana cyst

'Cross-eyed' cyst with 1-4 nuclei and a button-hole appearance.

Iodamoeba butschlii trophozoite

(12-15 µm) with non-progressive, heavily vacuolated cytoplasm and large basket-shaped nucleus.

Iodamoeba butschlii cyst

(10-12 µm) oval or triangular, with a large glycogen mass that stains dark brown in iodine prep.

Key characteristic of Iodamoeba butschlii

Cyst contains a large glycogen mass.

Transmission method of Entamoeba histolytica

Contaminated food or water ingestion.

Common setting for liver abscess formation by Entamoeba histolytica

When pressing on the biliary tract.

Common location of amoebic ulcers

Caecum and sigmoidorectal region.

Method for diagnosing Entamoeba histolytica

Concentration technique during stool examination.

Stool exam for Entamoeba histolytica

Gold standard diagnostic method.

Drugs effective against invasive amoebiasis

Metronidazole is the drug of choice.

Characteristics identifying Entamoeba dispar

Morphologically identical to E. histolytica but non-invasive.

Commensal in intestines

Entamoeba coli is a nonpathogenic intestinal amoeba.

Absence of cyst stage in

Entamoeba gingivalis, which only has a trophozoite stage.