PROTOZOA AMOEBA

Protozoa: The protozoa are a diverse group of unicellular, eukaryotic organisms. Many have evolved structural features (organelles) that mimic the organs of multicellular organisms. Reproduction is generally by mitotic binary fission, although in some protozoal species, sexual (meiotic) reproduction with several variations occurs as well. Only a few of the many tens of thousands of protozoan species are pathogenic for humans.

Clinically important protozoa: Many of these protozoa have both a dormant, immotile cyst stage (the infective stage) that permits survival when environmental conditions are hostile, and a motile, actively feeding and reproducing vegetative ( trophozoite ) stage (diagnostic stage). For convenience, the protozoa are classified according to their mode of locomotion. The clinically relevant protozoa are thus divided into four groups.

Classification of protozoa: Either by mode of locomotion:

Or by site where infection occurs :

AMOEBA: Can be either free living or parasitic. Parasitic Amoeba: the parasitic is either pathogenic: Entamoeba histolytica, or non-pathogenic: Entamoeba coli, Iodamoeba butschlii, Endolimax nana. Pathogenic free living amoeba: Naegleria and Acanthamoeba sp.

Entamoeba histolytica: We can see 2 stages : Cyst, trophozoite. Cyst: define cell wall, small, from 1-4 nuclei, the karyosome is in the center of the nucleus. Trophozoite: start to motion, change its cell wall to elongated, have pseudopodia, still small, with 1 nuclei contain also karyosome in the center.

Glass slides for E.histolytica Trophozoiate Trophozoite

Entamoeba histolytica Cyst Cyst

Entamoeba coli Also with 2 stages: cyst and trophozoite. Cyst: larger than E.histolytica, with 4-8 nuclei, if 4 there is no confusion with E.histolytica because it’s bigger and the karyosome is eccentric. Trophozoite: same psuedopodia shape but larger than E.histolytica, nuclei with eccentric karyosome, other things such as ingested particles or RBC’s and glycogen mass are not clear.

Entamoeba coli Cyst Trophozoite

Endolimax nana Very small in size, smaller than E.histolytica . With 4 nuclei seen as a holes inside the cyst.

Endolimax nana

Iodamoeba butschlii Cyst small in size but larger than E. nana may be seen as an oval or ovoid shape have 1 large nucleus with glycogen mass, some time it may seen dark or as a hole with central large karyosome.

Iodamoeba butschlii

Free living amoeba: Acanthamoeba

Naeglaria: