Entamoeba coli

Morphology, life cycle, diagnosis, symptoms, and treatment.

1. Entamoeba coli Prepared by: Veronica Baje

2. Entamoeba coli Entamoeba coli is a non-pathogenic species of Entamoeba that frequently exists as a commensal parasite in the human gastrointestinal tract. E. coli is important in medicine because it can be confused during microscopic examination of stained stool specimens with the pathogenic Entamoeba histolytica.

3. Trophozoites Measure between 18 to 27 μ m. Some trophozoites may be as small as 12 μ m, whereas others may be as large as 55 μ m. Equipped with blunt pseudopods. Exhibits sluggish, nonprogressive motility.

4. Cysts Vary in size from 8 to 35 μ m and average of 12 to 25 μ m. Thick cell wall surrounds the round to spherical cyst. One to eight nuclei with the typical nuclear features may be seen in unstained as well as as stained preparations.

5. Life Cycle  Cysts are typically found in formed stool, whereas trophozoites are typically found in diarrheal stool. Intestinal colonization with nonpathogenic amebae occurs after ingestion of mature cysts in fecally contaminated food, water, or fomites.  Excystation occurs in the small intestine  and trophozoites are released, which migrate to the large intestine. The trophozoites multiply by binary fission and produce cysts, and both stages are passed in the feces 

6. Laboratory Diagnosis Stool examination is the method of choice for the recovery of E. coli trophozoites and cysts.

7. Clinical Symptoms As with infections of E. hartmanni , infections with E. coli are usually asymptomatic.

8. Treatment E. coli is considered a nonpathogen. Treatment, therefore, is usually not indicated.