PATHOGENIC Intestinal Amoebas

What are the only 2 pathogenic intestinal amoebae?

1. Entamoeba histolytica

2. Blastocystis hominis

What is the method of transmission of ALL intestinal amebae?

Orally from fecal contaminated sources

CYST STAGE CONSUMPTION

What feature do ALL amebae have that allows for movement and feeding?

Pseudopods

What are the CHARACTERISTICS of the Entamoeba histolytica trophozoite stage?

• INGESTED RBCs (larger dark dot not to be confused with the nucleus)

• SMALL CENTERED KARYOSOME

• 15-25um average size

• Finely granular cytoplasm

REMEMBER THAT TROPHOZOITE’S ARE IRREGULARLY SHAPED

What are the CHARACTERISTICS of the Entamoeba histolytica cyst stage?

• SMOOTH ROUNDED ENDS of chromatoidal bars

• Round and 10-20um

• 1-4 nuclei with SMALL CENTRAL KARYOSOME

What disease does Entamoeba histolytica cause?

Dysenteric Bowel Disease

ABCESS and ULCERING

CAN SPREAD TO OTHER ORGANS VIA EXPOSURE TO CIRCULATORY SYSTEM

What is Amebic dysentery?

• Bloody/mucousy DIARRHEA

• LOW FEVER

• NO granulocytosis

CAUSED FROM THE BREAKING OF THE MUCOUSAL WALL

What is the Life Cycle of PATHOGENIC Intestinal Amoeba

1. Consumption (Oral) of contaminated fecal matter, WHICH CONTAINS CYST INFECTIOUS STAGE

2. Upon entering the intestine, they EXCYST leading to TROPHOZOITE

3. Trophozoite undergoes BINARY FISSION

4. Trophozoites ADHERE to the mucous layer of the intestine

5. EXCRETE ENZYMES, which break down the mucous layer

6. Lysis of intestinal epithelial cells

7. INVASION deeper into the layers of the mucosa

8. Potential exposure to the circulatory system, leading to abscess and ulceration of other tissues

What are the characteristics of the Blastocystis hominis trophozoite stage?

• LARGE CENTRAL VACUOLE (AT VACUOLAR STAGE)

• Nucleus pushed to edges

• 5-15um

What symptoms does Blastocystis hominis produce?

• Diarrhea

• ANOREXIA

• Flatulence

• Abdominal Cramping