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Entamoeba histolytica 2020
This document provides an overview of Entamoeba, including its classification, morphology, life cycle, virulence factors, transmission, clinical features, diagnosis, and treatment. Key points include: - Entamoeba histolytica is a pathogenic protozoan that can cause intestinal and extra-intestinal infections like amoebic dysentery and liver abscess. - It has three morphological stages - trophozoite, precystic, and cystic stages. Trophozoites cause tissue invasion and disease. - The infective transmissive stage is the mature quadrinucleated cyst which is ingested and excysts in the intestine. - Virulence factors like lect
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Entamoeba histolytica 2020
- 1. Entamoeba Dr. Md. AbdullahYusuf Associate Professor of Microbiology Email: ayusuf75@yahoo.com
- 2. Objectives • Protozoa • Basicmeaning • Members of the genus • Morphology • Life cycle • Virulence factors and related events • Mode of transmission • Clinical features • Sequelae and complications • Diagnosis • Treatment
- 3. Protozoa • Definition –A singlecell like unit which is morphologically & functionally complete • Differences from metazoa –Unicellular –Single cell perform all function • Morphology –Cytoplasm: Ectoplasm & Endoplasm –Nucleus
- 4. Classification: Protozoa According toorgan of Locomotion • Motile –Pseudopodia –Flagella –Cilia • Non-Motile –Plasmodium species
- 5. Organ of Locomotion Motilitywith Flagella • Urogenital Flagellates –Trichomonas vaginalis • Intestinal Flagellates –Giardia intestinalis • Haemo- & Tissue flagellates (Blood & Tissue) –Leishmania species –Trypanosoma Species
- 6. Organ of Locomotion •Motility with Pseudopodia –Entamoeba histolytica –Naegleria fowleri –Acanthamoeba castellanii • Motility with Cilia –Balantidium coli
- 7. Classification: Protozoa According toHost Requirement • Second Host not Required –Entamoeba histolytica –Giardia intestinalis • Second Host not Required –Trypanosoma cruzi –Plasmodium vivax –Leishmania donovani
- 8. Classification: Protozoa According toLocation/Habitate • Large Intestine –Entamoeba histolytica • Small intestine (Intestinal Flagellates) –Giardia intestinalis • Urogenital Flagellates (Vagina in female & Urethra in Male) –Trichomonas vaginalis
- 9. Classification (Conti..) • Blood –Plasmodiumspecies (RBC) –Leishmania species (Monocyte) –Trypanosoma species (Plasma)
- 10. Classification • Intestinal protozoa –Giardialamblia (flagellate) –Entamoeba histolytica (ameba) –Cryptosporidium hominis (sporozoa) –Cyclospora cayetanensis (sporozoa) • Sexually transmitted protozoan infection –Trichomonas vaginalis (flagellate)
- 11. Classification Blood and tissueprotozoan infections • Flagellates –Trypanosoma –Leishmania • Amebae –Entamoeba histolytica –Naegleria fowleri –Acanthamoeba castellanii
- 12. Classification • Sporozoa –Plasmodium Species –Babesiamicroti –Toxoplasma gondii • Microsporidia
- 13. Important Protozoa • Entamoebahistolytica • Giardia lamblia • Trichomonas vaginalis • Leishmania Species • Plasmodium Species • Toxoplasma gondii
- 14.
- 15. Basic meaning andmembers • Basic meaning of Entamoeba –Enta means intestine –amoeba means protozoa with pseudopods
- 16. Member of theGenus • Pathogenic • Non-Pathogenic
- 17. Member of thegenus • Pathogenic –Entamoeba histolytica (histo-tissue, lytica-that lyze)
- 18. Member of thegenus Non-Pathogenic Entamoeba coli –coli-colon –reside in colon Entamoeba dispar –dispar-disparity with E. histolytica
- 19. Non-Pathogenic Entamoeba Entamoeba hartmanni –Hartmanis the discoverer) Entamoeba gingivalis –Gingiva means gum –reside in mouth
- 20. Morphology Three morphological stages •Trophozoite –Active –motile • Precystic stage • Cystic stage –Resistant –non-motile
- 21. Two Events Encystation • conversionof trophozoite into cyst • Occur only within intestinal lumen Excystation • conversion of cyst into trophozoite • Occur in intestine after ingestion of mature cyst
- 22. Methods of Reproduction •Maturation of cyst –from one nucleus stage to 4 nuclei stage • Trophozoites multiply –by simple binary fission • Cyst not multiply • Encystation not a reproductive process
- 23. Morphology of Trophozoite •Growing or feeding stage • Actively motile by pseudopodia • Shape changes due to pseudopodial movement • Cytoplasm divided into –clear outer ectoplasm –inner granular endoplasm
- 24. Morphology of Trophozoite Endoplasmcontains • Nucleus • Food vacuoles Food vacuoles contain –bacteria or red blood cells • Can’t get in stool examination
- 25. E.histolytica: trophozoite ofE.histolytica with ingested erythrocytes of Gomori‘s trichrome
- 26. E. histolytica: invasivetrophozoites contain erythrocytes and bacteria (H&E stain).
- 28. Morphology of Cyst •Spherical in shape • Thin transparent wall • Contain 4 nuclei in mature cysts • Fine uniform granular Peripheral chromatin –with small discrete central karyosome –Differentiates it from other nonpathogenic species
- 29. Morphology of Cyst •Can find in stool examination • Can’t found in Liver abscess • Cyst not develop –in Intestine wall –Inside tissues of human –In liver abscess –In lungs abscess –In metastatic Invasion of other organs
- 32. Life cycle • Infectivestage/Form –Mature Quadrinucleated Cyst • Pathogenic stage –Trophozoite • Route of infection –Feco-oral • Site of lesion –Large intestine
- 33. Life cycle • Diagnosticstage –Cyst in Stool –Trophozoite in Liver Abscess
- 35. Spread of Infection Maturecyst in stool • House fly carrying the cyst from faeces to food • Infected faeces used as manure for growing vegetables • Carrier handling the food without hand washing
- 36. Why cyst infective? •Ingested qudrinucleated cysts –resists the action of gastric juice • Ingested Trophozoites –Destroyed by gastric juice
- 37. Life cycle • excystationoccurs in Lumen of Caecum –young trophozites come out • Cysts can survive in environment for 12 to 30 days –resistant to chemicals
- 38. Life Cycle • Trophozoiteslive and multiply in –Crypts of mucosa of large intestine –Feed starches & mucosal secretions –Interacting with normal gut flora (bacteria) –Hydrolyze mucosal cells –Causing amoebic colitis –Reach submucosa & blood vessels • Travel in blood to other organs –liver, lungs, skin
- 40. Virulence factors • Galactoseand N-acetyl-D-galactosamine (Gal/GalNAc) specific lectin – helps to bind trophozoites with colonic mucin glycoproteins. • Apoptotic killing of host cells –occurs by a novel pathway • Pore forming protein (Amoebopore) –kills endocytosed bacteria and cause necrosis of host cells
- 41. Virulence factors (Conti..) •Anti complement activity –resist destruction by lectin mediated complement activation • Motility –probably promote invasion by the cytoskeleton-induced motility • Enzymes –like Proteases, Collagenases, elastase, hyaluronidase that degrade the extracellular matrix
- 42. Virulence Events Invasion isfacilitated by many factors like – pore forming proteins – Proteases – Motility – phagocytosis
- 43. Diseases Caused byE. histolytica • Primary or Intestinal Lesion –Acute amoebic dysentery (extensive ulcers) –Amoebic colitis/Chronic Intestinal Amoebiasis –Amoebomas
- 44. Diseases Caused byE. histolytica • Secondary or Metastatic or Extra- intestinal Lesion –Amobic liver abscess/Hepatic amoebiasis –Pulmonary amoebiasis: Primary & Secondary –Cerebral Amoebiasis/Brain abscess –Cutaneous Amoebiasis –Splenic abscess
- 45. Amoebomas • These aretumour-like lesions of the colonic wall • can measure up to several cm
- 46. Hall mark ofamoebic dysentery Amoebic ulcer • Trophozoites invade tissues • cause extensive destruction of the colonic mucosa • Initially produces small, discrete erosions • then extend through the mucosa into the submucosa • expand laterally to produce flask-shaped lesions
- 47. Ulcer Characteristics • Flaskshaped ulcer • Ragged margins & bases –due to digesting effect of proteases • Floor remains full of altered blood from oozing of the side walls • Base of the ulcer usually remains limited to muscularis mucosa –rarely reach to submucosa and up to muscularis externa
- 48. Clinical Features ofIntestinal Amoebiasis • Passage of stool mixed with Mucus ±Blood • Intermittent diarrhoea –usually 4-6 times per day • Tormina –Severe abdominal cramps • Tenesmus –Feeling of incomplete Evacuation • General malaise • weight loss in chronic cases
- 49. Clinical Features ofHepatic Amoebiasis • Pain in right hypochondrium or generalized abdominal pain • Low grade irregular prolonged fever • Enlarged tender liver • Anorexia and weight loss • Jaundice • Raised right dome of the diaphragm
- 51. Characteristic of Pusof Amoebic Liver Abscess • Chocolate brown colour –Anchovy-sauce pus • Thick consistency • Bacteriological sterile • Mixed of slough liver tissue & blood • Cyst not found • Trophozoites found • Usually single large, abscess in Ultrasonography
- 52.
- 55. Differences between Amoebic& Bacillary Liver Abscess Points Amoebic Abscess Bacillary Abscess Size Large Small Number Single Multiple Pus colour Chocolate brown Pale colour Fever Low grade High grade Susceptible person Chronic amebiasis IV drug abusers Culture No bacteria Bacteria found Pus cell Occasionally pus Plenty of pus cell
- 56. Complications of Intestinal Amoebiasis •Haemorrhage from ulcer • Perforation of ulcer • Ameboma growth into intestinal lumen –Causes Intestinal obstruction & intussuception • Abscess formation • Toxic Megacolon –dilation of colon causes 40% mortality
- 57. Metastatic Amoebiasis • Cerebralabscess • Lungs abscess • Liver abscess • Splenic Abscess • Amoebiasis cutis
- 58. Laboratory Diagnosis Principle • Specimen •Microscopic Examination • Culture • Serology • Molecular test
- 59. Basic Principles • Microscopicdemonstration of –trophozoite or cyst of E. histolytica • Antigen detection from stool • Nucleic acids techniques • Hepatic amoebiasis diagnosed by –Antigen detection from blood and pus from liver –Antibody detection from serum
- 60. Microscopic Examination • Freshlypassed stool –Cyst
- 61. Diagnosis of HepaticAmoebiasis • Diagnostic aspiration • Liver biopsy • Exam of blood • Exam of stool • Serological tests • Radiological exam • Ultrasonography of Hepatobiliary system
- 62. Treatment • Drug ofchoice for symptomatic intestinal amoebiasis –Metronidazole 400mg tds fro 5 days –Secnidazole 1000mg 2 tab stat –Tinidazole –Ornidazole
- 63. Treatment Asymptomatic cyst passers •Diloxanide furoate • Iodoquinol (Diiodohydroxyquin) • Paromomycin • Nitazoxanide • Secnidazole • Chloroquin
- 64. Entamoeba dispar • E.dispar is non invasive • Morphologically similar to E. histolytica • First identified in 1925 • In 1978, isoenzyme analysis separate the two species
- 65. Free Living Amoeba •Name –Acanthemoeba –Negleria • Disease –Primary meningoencephalitis
- 66. Clinical & LabDifferences between Amoebic & Bacillary Dysentery Points Amoebic Bacillary Number of Motion 6 to 8 >10 Odour Offensive odourless Colour Dark red Bright red Composition Blood & mucus mixed faeces Blood & mucus No faeces RBC clumps Rouleaux Pus cell Scanty Plenty Culture E. histolytica Bacteria
- 67.