Protozoans

• Reproduction is generally by mitotic binary fission
• Protozoans - Lowest form of animal life.
• Cytostome : Procurement & Ingestion of food.
• Cytopyge : Excretion or Discharge of metabolic waste.
• Contracting vacuole - regulation & maintenance of osmotic pressure.
• • Organelles – metabolic & vital functions.
• • Nucleus – genetic material transfer.
• Common Stages of Development: Trophozoites, Cyst
• Trophozoites: Motile stage, vegetative, very sensitive, less resistant, easily destroyed, found in fluid or watery stool sample
• Cyst: non motile stage, resistant stage (has 2 layers), infective stage, found in formed stool sample.
• Encystation : Trophozoites to cyst, happens in large intestine.
• Excystation : Cyst to trophozoite, happens in small intestine.
• Kingdom : Protista
• FLAGELLATES, AMOEBAS, CILIATES, SPOROZOA - Classificiations of Protozoans
• amoebas - move by extending cytoplasmic projections
• flagellates - move by rotating whip-like flagella
• ciliates - move by synchronous of beating hair-like structures
• sporozoa - generally have non motile adult forms
• All amoeba inhabit the large intestine except, E. gingivalis.
• All amoeba develop into cystic stage except, E. gingivalis.
• All amoeba are commensals except, E. histolytica.
• Amoebiasis is applied only to E. histolytica.
• Entamoeba histolytica - First describe in 1875 in young Russian peasant in the port of Arkhangelsk. ❖Most invasive of the parasites. ❖Humans are only host.
• Trophozoite - Invasive stage
• Entamoeba histolytica - Trophozoite 10- 60 um Centrally located karyosome
• 10- 60 um - size of E.histolytica Trophozoite
• Entamoeba histolytica - w/ RBC but no bacteria or cell detritus (clean-looking)
• Entamoeba histolytica - consists of thin nuclear membrane w/ layer of uniformly sized fine chromatin granules
• Entamoeba histolytica - Unidirectional & progressive 1 pseudopod (finger-like)
• 10-16 um - size of E.histolytica cyst
• Cyst - infective stage of protozoans
• 4 - number of nuclei in E.histolytica
• Round or oval in shape - shape of E.histolytica cyst
• Quensel’s Iodine – BEST FOR TROPHOZOITE!!!
• Lugol’s Iodine – BEST FOR CYST!!!
• Culture- more sensitive but results are obtained in a week (e.g. Robinson’s culture)
• Concentration methods - FECT and MIFC
• Polymerase Chain Reaction (PCR) - Gold standard in diagnosis detects DNA sequence of the adherence lectin of E. histolytica & differentiates it from E. dispar.
• Intestinal – Non-dysenteric colitis
• .Extraintestinal - * Liver , * Nonsuppurative liver abscess