AMOEBAE P.ANUSHA

Structurally simple protozoa. No fixed shape. INTRODUCTION Structurally simple protozoa. No fixed shape.

CLASSIFICATION Phylum : Sarcomastigophora Subphylum : Sarcodina Superclass : Rhizopoda Class : Lobosea Subclass : Gymnamoeba Order : Euamoebida, Amoebida, Schizopyrenida.

Free-living Intestinal FREE-LIVING AMOEBAE:- Occasionally cause meningoencephalitis. They include Genus: Naegleria, Genus: Acanthamoeba, Genus: Balamuthia.

Naegleria :- Class : Lobosea Subclass : Gymnamoebia Order : Schizopyrenida. Acanthamoeba :- Order : Amoebida Suborder : Acanthopodina Balamuthia :- Family : Leptomyxididae.

INTESTINAL AMOEBAE :- They belong to Subphylum : Sarcodina Superclass : Rhizopoda Class : Lobosea Subclass : Gymnamoebia Order : Amoebida Family : Endamoebidae Entamoeba Endolimax Iodamoeba

GENUS : ENTAMOEBA This genus includes amoebae that have : Small karyosome - Zone of condensed chromatin filaments at the centre of nucleus in interphase Nucleus - -Spherical -Has distinct nuclear membrane lined with chromatin granules

Species of Entamoeba : E. histolytica, E. dispar, E. hartmanni, E. coli, E. gingivalis, E. polecki.

ENTAMOEBA HISTOLYTICA

History :- Discovered by LOSCH in 1875 in the dysenteric feces of a patient & in the colonic ulcers at autopsy in Russia. He inoculated it through the rectum of dog & produced dysentery in it. William OsIer reported the case of a young man with dysentery who died of liver abscess. Councilman & lafleur in 1891 established the pathogenesis of Amoebic dysentery & Amoebic liver abscess.

Distribution :- Habitat :- It causes – Amoebic dysentery, Hepatic amoebiasis, Other extra-intestinal lesions. Distribution :- Worldwide. Common in places wherever sanitation is poor. Habitat :- Trophozoite – in lumen,mucosa & submucosa of large intestine

MORPHOLOGY TROPHOZOITE :- E.histolytica occurs in 3 morphological forms : Trophozoite, Precyst, Cyst. TROPHOZOITE :- Growing or feeding stage. It is the only form present in the tissues. Size : 8µm – 30µm.

Cytoplasm : Consists of 1.Ectoplasm :- - Outer,clear,transparent & refractive layer 2.Endoplasm :- - Inner finely granular layer . - Ground glass appearance. - contains nucleus, food vacuoles, leucocytes, tissue debris, ingested erythrocytes. (characteristic feature)

Nucleus : Spherical in shape. 3.5 µm in size. Distinct nuclear membrane lined with chromatin granules. Central dot-Like karyosame surrounded by clear halo. Cartwheel appearance.

Trophozoites divide by binary fission once in about 8hrs. Actively motile with help of pseudopodia. PSEUDOPODIA are long,finger shaped extensions of ectoplasm into which endoplasm flows. Crawling or gliding movement seen. Nourishes mainly on bacteria and cytolysed tissue substances.

PRECYST :- Size : 10µm - 20µm. Smaller than trophozoite but larger than cyst. Round or oval ,colourless. Has a blunt pseudopodium projecting from the periphery. Contains – a large glycogen vacuole, 2 chromatoid bars.

Cyst :- Infective stage. Spherical in shape. Size : 10µm - 16µm. Mature cyst : - Quadrinucleate. - Nucleus is similar to that of trophozoite. - Cytoplasm is granular,contains rod-like chromatoid bars & glycogen mass.

Cyst is surrounded by a chitinous wall. Thus, cyst is resistant to - Gastric acid. - Adverse environmental conditions. - chlorine conc. found in potable water. Quadrate cysts are found mostly in formed stools & in lumen of colon.

Iron-haematoxylin stain : Nuclear chromatin,chromidial bars-deep blue black. Glycogen mass – appears unstained.

Iodine stain : Glycogen mass – golden brown. Nuclear chromatin & karyosome – bright yellow. Chromidial bars – clear spaces,unstained.

Polyxenic cultivation : Boeck & Drbohlav’s diphasic medium. Consists of – egg slant base, Lock’s solution. Balamuth & Nelson monophasic medium. Includes – enteric bacteria/flagellate, starch/rice flour.

Clear liquid medium by Diamond for Axenic cultivation : Clear liquid medium by Diamond for initiation, maintenance, mass cultivation of amoebae. consists of – Trypticase, Ox-liver digest, Glucose, Cysteine, Ascorbic acid, Salts supplemented with horse serum & a vitamin mixture.

Axenic cultivation is essential for study of its : Pathogenecity. Immunological & biochemical properties. Invitro drug susceptability testing. Preparation of axenic amoebic antigen.

LIFE CYCLE Host : Human. Infective stage : Cyst. Source of infection : Contaminated food & water. Route of infection : Ingestion.

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