Intestinal and Commensal Amoebae

Entamoeba histolytica

A pseudopod-forming non-flagellated protozoan parasite which causes non-invasive, invasive, and extra-intestinal diseases

Infective cyst and invasive trophozoite

Life stages of Entamoeba histolytica

NON-INVASIVE DISEASE

present as asymptomatic luminal amoebiasis with cysts being passed out in the stool

INVASIVE INTESTINAL DISEASE

Amoebic colitis presents as gradual onset of abdominal pain and diarrhea with or without blood and mucus in the stool.

perforation and secondary bacterial peritonitis

The most serious complication of amoebic colitis is…

Amoeba

It is sometimes mistaken as carcinoma

EXTRA-INTESTINAL DISEASE

Amoebic liver abscess (ALA) is the most common extra-intestinal form of amebiasis

a. Gal/Gal Nac lectin b. Cysteine proteinases c. Amoebapores

Expression of three (3) virulence factors facilitate invasion

flask-shaped ulcer

produce the characteristic ______ of amebic colitis found in the cecum, ascending colon and sigmoid.

Inflammatory and liver cells

_______ are lysed and the abscess is filled with necrotic debris described as anchovy-like sauce aspirate which is odorless and bacteriologically sterile

Natural Immunity

Mucin inhibition of amebic attachment to mucosal cells

Artificial Immunity

Activated T-cells lyse trophozoites in a contact-dependent process

Diloxanide furoate, Metronidazole

Drug of choice for the disease Asymptomatic Cyst Passer

Tinidazole, Metronidazole

Drug of choice for the disease Amoebic Colitis

Tinidazole

Drug of choice for the disease Amoebic Liver Abscess (ALA)

Commensal Amebae

May be mistaken for pathogenic Entamoeba histolytica

Indication of fecal contamination of food and water

cyst and trophozoite

Diagnostic stage of Commensal Amoeba

mature cysts ingested

Infective stage of Commensal Amoeba

Entamoeba dispar

Cysts have 4 nuclei that characteristically have centrally-located

karyosomes and fine, uniformly disdistributed eripheral chromatin

Entamoeba hartmanni

Cysts are similar to E. histolytica but smaller (5–10 μm) and does not ingest RBCs

Entamoeba coli

Cysts are usually spherical but may be elongated and measure 10–35 μm and have at least 8 nuclei

Entamoeba polecki

Cysts measure 9–25 μm and are usually uninucleated

Endolimax nana

Cysts are spherical to ellipsoidal in shape, about 5-10 um and quadrinucleated when mature

Iodamoeba butschlii

Cysts vary from nearly spherical to ellipsoidal in shape and measure 5–20 μm