E. coli
- Non-pathogenic amoeba found in caecum and colon of man and other animals.
- Morphological character to differentiate it from histolytica are
|
Characters |
E. histolytica |
E. coli |
|
Vegetative form or trophozoite form |
||
|
Size |
20-30 µm |
20-40 µm |
|
Mortality |
Active and progressive |
Sluggish and no progressive movement |
|
Inclusion in food vacuole |
Only RBC in fresh specimen |
Bacteria are present |
|
Nucleolus |
Situated at center of nucleus (Eccentric) |
Excentrical |
|
Nuclear membrane |
Inner surface is lined by row of fine chromatin granules |
Lined by coarse chromatin granules |
|
Cystic form |
||
|
Size |
5-20 µm |
15-30 µm |
|
Shape |
Spherical |
Spherical |
|
Cytoplasm |
Greenish yellow |
Yellow brown |
|
Chromatin rod |
Thick rod like with rounded ends |
Filamentous with pointed or square shape |
|
Nuclei |
4 nuclei in mature cyst |
8 nuclei in mature cyst |
|
Nucleolus |
Centrally present |
Excentrically present |
E. gingivalis
- Found in gums of man, dog, cat, monkey, etc.
- Causes pyorrhea in some cases
- No cyst formation occurs. Only trophozoite is seen which measures 5-35 µm in diameter.
- Produces multiple pseudopodia which are blunt and large
- Chromatin granules lining the inner surface of nuclear membrane are small and continuous.
- Transmission occurs through fomite.
E. bovis
- Found in cattle
- Size of trophozoite is 5-20 µm.
- Cytoplasm is filled with vacuoles
- Nucleus is large and with large central endosome made up of compact mass of granules.
- Cyst is uninucleated and size is about 4-15 µm in diameter.
Note:
- Amoeba with 8 nucleated cysts: coli
- Amoeba with 4 nucleated cysts: histolytica, E. hartmanni, E. equi
- Amoeba with 1 nucleated cyst: bovis, E. ovis , E. suss
- Amoeba with unknown nucleated cysts: gingivalis, E. canibucaalis