Commensal Ameba

• Entamoeba coli

  • Transmitted via ingestion of infective cyst
  • More common than other human amebae
• Trophozoite of E. Coli

  • 1 nucleus
  • Eccentric karyosome
  • Coarse, rough peripheral chromatin
  • Appearance: Dirty-looking cytoplasm (contains bacteria, debris, yeast)
  • Blunt, wider appearance of pseudopodia
• Cyst of E. Coli

  • 8 nuclei
  • Appearance is larger than E. histolytica, thick cystic wall
  • The chromatoidal bar looks like broom stick/witch broom/splinter
• Entamoeba hartmanni


  Small race of E. histolytica
• Trophozoite of E. Hartmanni 


  Pseudopod structure that similar to E. histolytica

  Motility: Sluggish movement
• Cyst of E. Hartmanni

  Diffuse glycogen vacuole/mass structure (not seen in permanent stain)
• Entamoeba polecki

  • Ameba of pigs and monkeys
  • Most common parasite in Papua New Guinea
  • May resemble other Entamoeba species
  • Zoonotic infection: can be passed from animals to humans
• Cyst of E. Polecki

  • Large, centrally located
  • Chromatoidal bar structure but looked like angular/pointed appearance
• Endolimax nana

  • Smallest intestinal amebae
• Trophozoite of E. nana

  • Appearance is ingested bacteria, blunt and hyaline pseudopodia, food vacuoles are also present (which may contain bacteria)
• Cyst of E. nana

  • Large, prominent, blot-like karyosome
  • Oval, cross-eyed appearancew
• Iodamoeba butschlii

  • Ameba of swine (pigs)
  • Large, chromatin-rich karyosome surrounded by a layer of achromatic globules and anchored to the nuclear membrane by achromatic fibrils
• Tropozoite of Iodamoeba butschlii

  • "Basket of Flower" appearance due to (due to achromatic granules), triangular shaped
  • Glycogen vacuole structures and Iodine used to visualize this
• Entamoeba gingivalis

  • NO CYST STAGE
  • Ameba of oral cavity (gum line) and also found in tartar, gingival pockets of teeth, and tonsillar crypts (of unhealthy mouths, but may also be in healthy mouths)
  • May also be seen in the genital tract
  • Scavengers, eat debris
  • Can also ingest RBCs (but it’s rare)
  • Transmitted via direct-contact (kissing, sharing of personal items)
  • First amoeba in man
  • Can be seen in sputum sample (can go to the lungs)
  • Also found in AIDS patients
  • Found even in healthy people
  • Non-pathogenic, but can be seen in patients with pyorrhea alveolaris (gum infections)
• Trophozoite of E. gingivalis

  • Capable of ingesting WBCs
  • Numerous, blunt pseudopodia
  • Numerous food vacuoles that contain cellular debris (mostly leukocytes from the ingested WBCs)