What is the Difference Between Entamoeba Histolytica and Entamoeba Coli

The main difference between Entamoeba histolytica and Entamoeba coli is that E. histolytica is parasitic whereas E. coli is a commensal. Furthermore, the trophozoite stage of E. histolytica is fairly abundant in amoebic dysentery while the trophozoite stage of E. coli is not abundant in stool.

Entamoeba histolytica and Entamoeba coli are two species of Entamoeba. Both live in the human gastrointestinal tract.

Key Areas Covered

1. Entamoeba Histolytica
     – Definition, Characteristics, Importance
2. Entamoeba Coli
     – Definition, Characteristics, Importance
3. What are the Similarities Between Entamoeba Histolytica and Entamoeba Coli
     – Outline of Common Features
4. What is the Difference Between Entamoeba Histolytica and Entamoeba Coli
     – Comparison of Key Differences                        

Key Terms

Amoebiasis, Cysts, Entamoeba coli, Entamoeba histolytica, Trophozoite

Entamoeba Histolytica – Definition, Characteristics, Importance

E. histolytica is a type of parasitic amoebozoan belonging to the genus Entamoeba. It infects humans and other primates and causes amoebiasis. Generally, E. histolytica causes histolysis, which literally means disintegration and dissolution of organic tissues.

Figure 1: Entamoeba histolytica

Although the trophozoite stage is the prominent growth form, it produces cysts, which are the transmission forms. Generally, cysts can survive outside the host in water, in soils, and on foods, especially under moist conditions on the latter. Infections occur when the food or water is contaminated with these cysts. Therefore, poor sanitary conditions increase the risk of amoebiasis.

Entamoeba Coli – Definition, Characteristics, Importance

E. coli is another type of amoebozoan belonging to the same genus. It is a non-pathogenic species that frequently exists as a commensal. However, this species plays a crucial role in medical examinations as it can often be confused with the pathogenic species of Entamoeba in the stool. Moreover, E. coli is immobile and its rounded shape is only visible in fresh stool specimens.

Figure 2: Entaemoeba coli cyst with Six Nuclei

Furthermore, the three distinct life stages of E. coli are the trophozoite stage, pre-cystic stage, and cystic stage. The trophozoite stage has a single nucleus and a thick membrane surrounding it. Furthermore, the number of nuclei in the cystic stage is a characteristic feature used to identify the species of Entamoeba.

Similarities Between Entamoeba Histolytica and Entamoeba Coli

• Entamoeba histolytica and Entamoeba coli are two species of the genus
• They belong to the class Archamoebae.
• Both live in the human gastrointestinal tract by maintaining a symbiotic relationship.
• Also, both are single-celled animals with a single nucleus.
• Furthermore, they have a single lobe pseudopod, taking the form of a clear anterior bulge.
• Trophozoite stage is their major growing stage of life.
• Moreover, their trophozoite is 10-20 μm in diameter and feeds primarily on bacteria.
• Their trophozoite divide by binary fission.
• Besides, they form cysts, the stage involved in transmission.

Difference Between Entamoeba Histolytica and Entamoeba Coli

Definition

Entamoeba histolytica refers to the agent of amebic dysentery, a disorder with inflammation of the intestine and ulceration of the colon, while Entamoeba coli refers to a non-pathogenic species of the genus Entamoeba that reside in the gastrointestinal tract of humans and other mammals. Thus, this is the main difference between Entamoeba histolytica and Entamoeba coli.

The Size of the Trophozoite

Furthermore, the size of the trophozoite of E. histolytica is 10-30 μm in diameter while the size of the trophozoite of E. coli is 20-40 μm in diameter.

Pseudopodia

The outline of the trophozoite of E. histolytica has finger-like pseudopodia while the outline of the trophozoite of E. coli has no prominent pseudopodia.

Mobility

Also, motility is another difference between Entamoeba histolytica and Entamoeba coli. The trophozoite of E. histolytica is actively motile while the trophozoite of E. coli is sluggishly motile.

Abundancy in Stools

The trophozoite stage of E. histolytica is fairly abundant in amoebic dysentery while the trophozoite stage of E. coli is not abundant in stool.

Ectoplasm

Moreover, the ectoplasm is prominent in E. histolytica trophozoites while the ectoplasm is not prominent in E. coli trophozoite.

Endoplasm

The endoplasm of E. histolytica trophozoites is finely granular with ingested RBCs while the endoplasm of E. coli is coarsely granular loaded with bacteria, yeasts, etc.

Vacuoles

In addition, the vacuoles of the trophozoites of E. histolytica are defined, scanty, and spherical while the trophozoites of E. coli have a number of vacuoles with clefts and cracks. Hence, this is also a difference between Entamoeba histolytica and Entamoeba coli.

Nucleus

The nucleus of the trophozoites of E. histolytica is small and indistinct in saline preparations while the nucleus of the trophozoites of E. coli is large and distinct.

Nuclear Membranes

Besides, the nuclear membranes of the trophozoites of E. histolytica contain uniformly stained chromatin while the nuclear membranes of the trophozoites of E. coli contain irregularly stained chromatin.

Karyosome

Another difference between Entamoeba histolytica and Entamoeba coli is that the karyosome of trophozoites of E. histolytica is central while the karyosome of the trophozoites of E. coli is eccentric.

The Size of the Precystic Stage

The size of the pre-cystic stage of E. histolytica is 5-15 μm in diameter while the size of the pre-cystic stage of E. coli is 12-17 μm.

The Size of the Cystic Stage

One other difference between Entamoeba histolytica and Entamoeba coli is that the size of the cystic stage of E. histolytica is 6-18 μm in diameter while the size of the cystic stage of E. coli is 10-30 μm.

Chromatid Body

While the cystic stage of E. histolytica has a bar-like chromatid body with rounded ends, the cystic stage of E. coli does not have a chromatid body.

Number of Nuclei in the Cystic Stage

The cystic stage of E. histolytica has one or four nuclei, which are not visible when unstained, while the cystic stage of E. coli has two or eight nuclei, which are visible when unstained.

Conclusion

E. histolytica is a type of Entamoeba that is parasitic in the gastrointestinal tract in humans, causing amebic dysentery with trophozoites in it. On the other hand, E. coli is another type of Entamoeba that lives as a commensal in the gastrointestinal tract in humans. Its trophozoites are less abundant in stools. Both E. histolytica and E. coli are two types of single-celled, eukaryotic animals transmitted through the formation of cysts. However, the main difference between Entamoeba histolytica and Entamoeba coli is the type of symbiotic relationship they maintain in the human gastrointestinal tract.

References:

1. Sabri, Mohammad. “Entamoeba Species.” University of Babylon. Available Here. 

Image Courtesy:

1. “Entamoeba histolytica” By Stefan Walkowski – Own work (CC BY-SA 3.0) via Commons Wikimedia   
2. “Entaemoeba coli cyst 6 nuclei” By Blueiridium – Own work (CC BY-SA 3.0) via Commons Wikimedia