Amoeba PDF

PROTOZOOLOGY  PROTOZOOLOGY ØIntestinal Amoeba (Pathogenic) ØCommensal Amoeba ØFree-living Pathogenic Amoeba ØFlagellates ØCiliates ØOther Intestinal Protozoa ØMalarial Parasite ØBlood and Tissue Flagellates ØCoccidian Protozoa Unicellular Motile Varies shape, size, locomotion/locom...

PROTOZOOLOGY  PROTOZOOLOGY ØIntestinal Amoeba (Pathogenic) ØCommensal Amoeba ØFree-living Pathogenic Amoeba ØFlagellates ØCiliates ØOther Intestinal Protozoa ØMalarial Parasite ØBlood and Tissue Flagellates ØCoccidian Protozoa Unicellular Motile Varies shape, size, locomotion/locomotor apparatus method group Protoplasm -Most important part of protozoa A. Cytoplasm 1. Ectoplasm a.) Locomotor apparatus q Pseudopodia- Amoeba q Flagella- Flagellates q Cilia- Cilliates q Undulating membrane- Flagellates b.) Structure for Procurement of food - Cytostome- cell mouth c.) Structure excretion of metabollic waste - Cytopyge- cell anus 2. Endoplasm- vital function/processes ØRibosomes Ø Mitochondria Ø Nucleus ØLysosomes Ø Vacuole –regulates the osmotic pressure  Protozoa- has only 2 stages: 1. Trophozoite – vegetative/ motile stage 2. Cyst- infective stage except for Trichomonas - non motile stage - non feeding stage Trophozoite Cyst (Encystation) w/c trophozoite develops into cyst Cysts Trophozoite (Excystation) Reproduction: Sexual-SYNGAMY Asexual- most of the protozoa reproduce by BINARY FISSION  Subphylum Sarcodina Is a subphylum of the Phylum Sarcomastigophora, of unicellular life forms that move by cytoplasmic flow. Some species use cytoplasmic extensions called pseudopodia for locomotion or feeding. Entamoeba histolytica Non-pathogenic amoeba Free Living amoebas Entamoeba histolytica Mode of transmission: ingestion, feco-oral –Sexually transmitted: possible male homosexuals Infective stage: mature cyst (4 nuclei) Trophozoite Note a pseudopodia with clear ectoplasm Size 12-30 micrometers Nucleus is hardly visible Cytoplasm may contain purple-colored, ingested red cells A single nucleus contains reddish, concentric karyosome, and peripheral chromatin evenly distributed Cyst Immature, binucleated cyst in stool specimen, Trichrome stained Spherical or ovoidal in shape, 12-20 micrometer in diameter Cytoplasm contains reddish-purple colored, cigar- shaped chromatoid bars Each nucleus contains reddish, concentric karyosome, and peripheral chromatin evenly distributed Pathogenesis of Amoebiasis NON-INVASIVE –ameba colony on intestinal mucosa –asymptomatic cyst passer INVASIVE –necrosis of mucosa ® ulcers, dysentery –ulcer enlargement ® severe dysentery, colitis, peritonitis –metastasis ® extraintestinal amebiasis Geographic Distribution Worldwide, with higher incidence of amoebiasis in developing countries. In industrialized countries, risk groups include male homosexuals, travelers and recent immigrants, and institutionalized populations. Manifestations ulcer enlargement ® severe dysentery perforation of intestinal wall ® peritonitis local abscesses 2o bacterial infections occasional ameboma (=amebic granuloma) ameboma = inflammatory thickening of intestinal wall around the abscess (can be confused with tumor)  Extraintestinal Amebiasis Metastasis via blood stream Primarily liver (portal vein) –other sites less frequent Ameba-free stools common  Amebic Liver Abscess Chocolate-colored ‘pus’ –necrotic material –usually bacteria free Lesions expand Further metastasis  Pulmonary Amoebiasis Rarely primary Rupture of liver abscess through diaphragm 2o bacterial infections common Fever, cough, dyspnea, pain  Diagnosis Extraintestinal (hepatic) – symptoms – history of dysentery – enlarged liver – serology – imaging (CT, MRI, ultrasound) – abscess aspiration – reddish brown liquid – trophozoites at abscess wall  Treatment Asymptomatic Iodoquinol or Paromomycin Symptomatic Metronidazole or Tinidazole Drain liver abscess  Prevention and Control Avoid fecal-oral transmission normally associated with travelers diarrhea  Non-Pathogenic Amoebas Entamoeba dispar Entamoeba hartmanii Entamoeba coli Entamoeba gingivalis Entamoeba polecki Entamoeba moshkovskii Endolimax nana Iodamoeba butschlii  Commensal Amoeba Entamoeba dispar Same morphologic features as Entamoeba histolytica but has genetic and biochemical differences Attributed as non-pathogenic Entamoeba histolytica strain Entamoeba coli Trophozoites –20-25 mm –broad blunt pseudopodia Nuclear structure –peripheral chromatin –small karyosome –irregular peripheral chromatin –eccentric karyosome Cyst Mature, infective cyst in stool specimen, Trichrome-stained Large, spherical or ovoidal shaped cyst, 15-25 micrometer in diameter Usually contains 8 nuclei, but 16 nucleated cyst can be found sometimes Each nuclei has eccentric karyosome Peripheral nuclear chromatin asymmetrically distributed, giving an uneven thickness look to nuclear membrane Sometimes, chromatoid body with splintered ends can be seen in cytoplasm Entamoeba hartmanni Cysts –6-8 nm –4 nuclei (mature) –blunt chromatoid bodies –CB persist in mature cysts Trophozoites –8-10 nm Nuclear structure –peripheral chromatin –small karyosome Entamoeba polecki rarely found in humans commensal of pigs & monkeys mature cyst has one nucleus The cysts measure usually 11 to 15 µm (range 9 to 18 µm) and their shape varies from spherical to oval. The trophozoites measure usually 15 to 20 µm (range 10 to 25 µm). Entamoeba moshkovskii identical morphology as E. histolytica free-living (sewerage) Endolimax nana Cysts –6-8 mm –4 nuclei Trophozoites –8-10 mm Iodamoeba bütschlii Cysts – 10-12 mm – 1 nucleus – glycogen vacuole Trophozoites – 12-15 mm Nuclear structure – no peripheral chromatin Entamoeba gingivalis oral cavity no cyst stage trophozoites nearly identical to E. histolytica periodontal disease Trophozoite Trophozoite, Trichrome-stained Look like Entamoeba histolytica Ingested leukocytes in cytoplasm is its distinct character