ENTAMOEBA HISTOLYTICA

Phylum Sarcomastigophora

Parasites includes Amoeba and Flagellates

Amoeba

• Subphylum Sarcodina

• Presence of pseudopodia (foot-like projections)

Flagellates

• Saubphylum Mastigophora

• Presence of whip-like flagella

Entamoeba

Naegleria

Acanthamoeba

Important Amoeba in Humans

Entamoeba coli

Entamoeba hartmani

Entamoeba dispar

Entamoeba moshkovskii

Entamoeba gingivalis

Commensal Amoeba

Entamoeba histolytica

Pathogenic Amoeba

Entamoeba polecki

Zoonotic Amoeba

Naegleria

Acanthamoeba

Free Living Amoeba

Entamoeba gingivalis

All entamoeba are lumen-dwelling protozoans except:

Entamoeba histolytica

All entamoeba are non-pathogenic except for:

Entamoeba gingivalis

All entamoeba has Cystic stage as their infective stage except for:

Entamoeba

Endolimax

Iodamoeba

3 Genera

Entamoeba

characterized by the presence of chromatin on the nuclear membrane

Cyst

Infective stage of Entamoeba

Trophozoites

Vegetative/reproductive stage of Entamoeba

Entamoeba histolytica

• most invasive

• 3rd most important parasitic disease

• 2nd cause of mortality among parasitic protozoans

Entamoeba histolytica

It ingests RBC

GalNac Lectin

Cysteine Proteinase

Amebapore

Virulence factors of E. histolytica

Entameoba histolytica Trophozoite

• size: 12-60um

• motility: progressive and directional movement

• unstained nuclei are not visible

• Karyosome is small and is often centrally located

• Cytoplasm is finely granular

Hematophagos trophozoites

• Trophozoites with ingested RBC

• Motile forms of Entamoeba histolytica

Trophozoites

What is larger? (Cyst or Trophozoites)

Hematoxylin stain

Trichome stain

Stains used for E. histolytica

Hematoxylin stain

• Cytoplasm: grayish

• Nuclear Membrane: bluish-black

• RBC Inclusion - pale

(for trophozoites)

Trichome stain

• Cytoplasm: green

• Nuclear Membrane: dark red

• RBC Inclusion - cherry red or green

(for trophozoites)

Swiss Cheese appearance of vacuoles

Degenerative stage of E. histolytica

Entameoba histolytica cyst

• size: 10-20um

• spherical

• Nuclei: Quadrinucleated (1-2-4)

• refractile cyst wall

• Cytoplasm: glycogen vacuoles, chromatic bodies, blunted or rounded ends

• cigar-shaped

4

• maximum of the nuclei of E. histolytica

• Mature quadrinucleutal cysts

Hematoxylin stain

• Chromatoidal bars: bluish-black stain

(cysts)

Trichome stain

• Chromatoidal bars- bright red

(cyst)

Amoebic dysentery

Severe amoebic colitis

Explosive daily liquid stools

Tenesmus

Mild Leukocystis

Flask-shaped ulceration

Pathogenesis (Intestinal) of E. histolytica

Amoebic dysentery

• invasive

• presence of blood and mucus in stool

Severe amoebic colitis

• steroid

• severely burned patient

Tenesmus

• painful spasms of the an@l sphinchter (rectal ulceration)

Mild Leukocystis

• WBC count: 12,000/uL but nnot higher than 16,000-20,000/uL

Direct Fecal Smear (DFS)

Antigen-Antibody Detection

Molecular Diagnosis

Liver Scan

Tissue Examination

Diagnosis for E. histolytica

DFS

presence of RBC in trophozoites and cyst in stool

IHA (Indirect Hybridization Assay)

ELISA (Enzyme-Linked Immuno Sorbent Assay)

EIA (Enzyme Immuno Assay)

Antigen-Antibody Detection for E. histolytica

PCR / Thermocycler

Equipment used for Molecular diagnosis for E. histolytica

Period Acid Schiff

Tissue examination where trophozoites appear bright pink in green-blue background

H&E Stain

Tissue examination that allow accurate demonstration of trophozoites

Southeast Asia

Africa

Central and South America

E. histolytica is mostly prevalent to these countries:

Non-invasive

Invasive

Intestinal Manifestations of E. histolytica

Non-invasive

Intestinal manifestation of E. histolytica where it just stays in the intestine

Invasive

Intestinal manifestation of E. histolytica where ulceration of intestinal walls occures

Metronidazole

First line of drug in the treatment of E. histolytica

Metronidazole

Tinidazole

Treatment of choice / drugs for E. histolytica