Intestinal and atrial amebae

Terms

  • Coarse = large

  • Fine = small

 

  • Achromatic granules = are not stained

  • Chromatic granules = are stained

o   Entamoeba histolytica, Entamoeba dispar , Entamoeba harmanni

K: small, discrete, usually central, bull's eye karyosome

PC: fine, uniform, evenly distributed

granules

  • E. Histolytica - may ingest RBC

  • E. dispar and harmanni - may ingest Bacteria

 

o   Entamoeba coli

K: large, eccentric

PC: coarse, irregular

Bacteria, yeast, other materials

 

o   Endolimax nana  

K: large and irregular (blot-like) 

Bacteria

 

o   Iodamoeba butschlii

K: central or peripheral; surrounded with achromatic granules

Bacteria, yeast, other materials

 

o   Entamoeba gingivalis

K: central and distinct

Food vacuoles, WBCs

LIFE CYCLE OF E. HISTOLYTICA

Infective stage = mature cyst

Mode of transmission = ingestion from contaminated food and water

2nd stage = metacyst

  • excsytation = exit cyst form and transform into trophozoite

    • happens in the small intestine

3rd stage = Multiplication

  • multiplication if high H2O

    • through binary fission = trophozoite in liquid stool

  • multiplication if low H2O

    • encystation = enter cyst form from trophozoite

      • large intestine

      • cyst in formed stool

1. Intestinal Amebiasis

▪ Acute/Symptomatic – incubation period of 2-3 days; presents with bloody diarrhea and abdominal pain

▪ Chronic/Asymptomatic – patients are considered as a carrier of cyst; stool is soft to well-formed

▪ Amoeboma – carcinoma like with granulomatous tissue

▪ Amoebic ulcers – flat-shaped ulcers

2. Extraintestinal Amebiasis

▪ Most common site liver; may hematogenously spread to other organs

o   Abscess seen in extraintestinal amebiasis = hepatic abscess

FREE-LIVING AMEBAE

Naegleri fowleri

o   Cyst

·        Small

·        Uninucleate

·        Double walled appearance with smooth outer wall (ectocytst)

o   Trophozoite

·        2 forms

·        Ameboid - lobate pseudopods (lobopods)

·        Flagella - 2 anterior flagella

·        Motility – rapid

o   Diseases

·        Primary ameboid meningoencephalitis – acute

o   Diagnostic stage

·        Trophozoite only

Acanthamoeba spp.

o   Cyst

·        Large

·        Uninucleate

·        Double walled appearance with wrinkled  outer wall (ectocytst)

o   Trophozoite

·        1 forms

·        Ameboid – spiny or fili form pseudopods (acanthopods)

·        Motility – slow

o   Diseases

·        Gamma ameboid meningoencephalitis – chronic

·        Keratitis

·        Skin lesion

·        Disseminated granulomatous disease

o   Diagnostic stage

·        Trophozoite and cyst

INTESTINAL AND ATRIAL FLAGELLATES

CYST

Gardia lambia

·        Axoneme

·        Parabasal bodies

Chilomastix mesnili

·        Fili curved

·        Shepherd’s crook

Enteromonas hominis

·        Bipolar nuclei – 2 nuclei at opposite sides

·        Resembles E.nana cyst

Retortamonas hominis

·        Cystosome extends above nuclei

·        Bird’s beak