University:
American Career College
Course:
MA700 | Clinical Procedures and Pharmacology
Academic year:

2021
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195

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47
Author:

VNever

Protozoology Overview & general characteristics of protozoa Classification of important medical protozoa Intestinal protozoa – Amoeba Amebiasis  Entamoeba histolytica -Morphology -Life Cycle Metazoa multicellular organisms, Parasite e.g. helminths (worms) Protozoa unicellular organisms, e.g. Plasmodium (malaria) Characteristics Eukaryote: a cell with a well-defined chromosome in a membrane-bound nucleus. Protoplasm Nucleus Cytoplasm Endoplasm: the inner layer of the cytoplasm, Cytoplasm which immediately surrounds the nucleus and is moderately dense and granulated. Ectoplasm: Enveloping the endoplasm is the less granular and more homogenous than endoplasm. Ameba (Entamoeba) Nucleus  Shape (form) •Vesicular nucleus Karyosome (endosome) Peripheral chromatin • Compact nucleus Malaria Balantidum Plasmodium  Number two nuclei may be similar in structure and function (e.g., Giardia) or dissimilar (e.g., Balantidium) Macronucleus & Micronucleus Giardia organelles Locomotor organelle Nutritional organelle Excretory organelle Locomotor organelle Pseudopodia Amebae Constantly changing shapes, move by ending out fingerlike extensions of their cell membranes called pseudopodia or “false-feet” projections. Locomotor organelle flagella In Flagellates Basal body Blepharoplast Kinetosome Locomotor organelle cilia In Ciliates Nutritional organelle  Some protozoa have no special site for the intake of food; they absorb liquid nutriment from the medium in which they live or ingest bacteria & microscopic food particles at any site on the body surface. Nutritional organelle  Some protozoa have no special site for the intake of food; they absorb liquid nutriment from the medium in which they live or ingest bacteria & microscopic food particles at any site on the body surface. Cell mouth (Cytostome)  Other protozoa have a specialized “cell mouth,” the cytostome, which is usually located laterally near the anterior end of the body. Nutritional organelle Cell mouth (Cytostome) Excretory organelle cell anus (Cytopyge)  Ciliate protozoa have a “cell anus,” the cytopyge, through which particulate food wastes are discharged. Excretory vacuoles at times serve for the collection of fluid wastes that are then ejected from the cell, usually at the aboral end. Reproduction asexual multiplication sexual multiplication Asexual multiplication Binary fission Binary fission: In the amebae, which have no axial gradient, there is no characteristic plane of division. Reproduction asexual multiplication sexual multiplication Asexual multiplication Binary fission In the flagellates, division is along a longitudinal axis Longitudinal Binary fission Reproduction Asexual multiplication Binary fission In the ciliates, division is in the transverse plane. Transversal Binary fission Reproduction Asexual multiplication Endodyogeny A form of asexual reproduction, favored by parasites such as Toxoplasma, in which two daughter cells are produced inside a mother cell, which is then consumed by the offspring prior to their separation. Reproduction Asexual multiplication Schizogony A form of asexual reproduction, in the malaria parasites, the production of merozoites is accomplished by several to many binary nuclear divisions within the schizont before the daughter organisms are fully formed. Reproduction Sexual multiplication All sporozoa have an alternation of asexual and sexual generations in their life cycle. 1- Asexual reproduction (schizogony): repeated Schizogony takes place, resulting some gametocyte. 2- Sexual reproduction (gametogony): the development of gametocyte into male and female gametes, which later fuse to form a zygote. 3- Asexual reproduction (Sporogony): the multiple fission (asexual division) of an encysted zygote or oocyte, resulting in the formation of sporozoites. Reproduction Sexual multiplication In the ciliates, sexual reproduction is accomplished by conjugation. Conjugation Protozoa Free-living forms are found in the sea, in deep and shallow fresh water, and in moist soil and subsoil. parasitic forms are parasites of plants, insects, other invertebrates, and of all groups of vertebrate hosts. Stage of Life Trophic stage (Trophozoite) is the active form. Cystic stage (Cyst) is the protective form. Cystic stage (Cyst) 1. Protective cyst 2. Reproductive cyst 3. Transmission (host to host) A parasite: “a living organism that acquires some of its basic nutritional requirements through its intimate contact with another living organism”. Parasites may be simple unicellular protozoa or complex multicellular metazoa. Host: “the organism in, or on, which the parasite lives and causes harm.” Zoonosis: “a parasitic disease in which an animal is normally the host – but which also infects human.” Definitive host: “the organism in which the adult or sexually mature stage of the parasite lives. Intermediate host: “the organism in which the parasite lives during a period of its development only (asexually stage).” Vector: “a living carrier (e.g.an arthropod) that transports a pathogenic organism from an infected to a non-infected host”. A typical example is the female Anopheles mosquito that transmits malaria. Symbiosis: an intimate association between two organisms Three types of symbiosis: 1. Parasitism: one organism lives in or on a second organism, called the host. – the host is harmed but usually survives 2. Commensalism: one organism benefits and the other neither benefits nor is harmed 3. Mutualism: both organisms benefit from the relationship Kingdom Animalia Taxonomy Subkingdom Protozoa Phylum Sarcomastigophora Phylum Apicomplexa Phylum Ciliophora Phylum Microspora Subkingdom Metazoa Phylum Nematoda Phylum Platyhelminthes Kingdom Animalia Taxonomy Subkingdom Protozoa Phylum Sarcomastigophora Subphylum Sarcodina Entamoeba Subphylum Mastigophora Phylum Ciliophora Phylum Apicomplexa Phylum Microspora Giardia Balantidium Cryptosporidium Microsporidium Medical Classification Location in the human body Body cavities protozoa (the digestive and urogenital tracts) The blood and tissue protozoa Intestinal protozoa Intestinal protozoa Sarcodina: Entamoeba histolytica** Entamoeba dispar Iodomoeba butschlii Endolimax nana Entamoeba coli Entamoeba hartmani Apicomplexa: Cryptosporidium parvum.** Isospora belli ** Cyclospora cayetanensis** Mastigophora: Giardia lamblia** Dientamoeba fragilis** Trichomonas hominis Chilomastix mesnili Ciliophora: Balantidium coli** Microsporidia: Enterocytozoon bienusi** (**=pathogenic) Amebae Genus: Entamoeba Species: E. histolytica E. dispar E. hartmanni E. coli E. gingivalis E. polecki E. moshkovskii Genus: Endolimax Species: E. nana Genus: Iodamoeba Species: I. bütschlii Entamoeba coli  most common endocommensal of humans  has a worldwide distribution  1-50% of the population can be infected worldwide  common inhabitant of the lumen of the cecum and colon of human.  Feeds on bacteria and any other cells available to it  does not invade tissues Entamoeba coli Trophozoite 15-50 µm Cyst 10-35 µm Entamoeba histolytica Trophozoite T:12-15 µm Minuta Cyst C:10-15 µm Trophozoites Cysts Entamoeba histolytica Entamoeba histolytica Entamoeba histolytica Trophozoite Hematophage Magnata T:20-60 µm Entamoeba dispar • Morphologically identical with E. histolytica • their DNA and ribosomal RNA are different E. histolytica /E. dispar Entamoeba moshkovskii • Morphologically identical with E. histolytica and E. dispar • their DNA and ribosomal RNA are different E. histolytica /E. dispar/E. moshkovskii Entamoeba hartmanni • Morphologically indistinguishable from E. histolytica/E. dispar similar to E. histolytica except that it is much smaller T:10-12 µm C:7-10 µm Entamoeba gingivalis • a common inhabitant of the mouth of human • lives on the surface of teeth and gums, in gum pockets and sometimes in the tonsillar crypts • Organisms are more common in persons with pyorrhea (gum disease) but they are not the cause of the condition • Prevalence is from 10 to 95% • Transmission: – kissing – droplet spray – sharing eating utensils Entamoeba gingivalis Trophozoite 10-35 µm Moves quickly Has numerous blunt pseudopodia Has numerous food vacuoles that contain cellular debris and bacteria and ingested leukocytes. • no cyst stage Endolimax nana Second most common endocommensal of humans worldwide distribution 1-30% Lives in the large intestine mainly near the cecum feed on bacteria Non-pathogenic Outstanding feature:  larger karyosome than those of the genus Entamoeba  absent peripheral chromatin Iodamoeba bütschlii  Not very common endocommensal in people  non-pathogenic  Lives in the large intestine Iodamoeba bütschlii Trophozoite: 12-16 µm nucleus: Single large vesicular nucleus with large chromatin- rich karyosome Cyst: 9-10 µm  oval-round  Uni-nucleated: Single nucleus  Prominent characteristic: • large glycogen vacuole which stains deeply with iodine

Introduction to Amoeba

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