Entamoeba histolytica, Extra intestinal amaoebiasis

1. Entamoeba
Dr. Md. Abdullah Yusuf
Associate Professor of Microbiology
Email: ayusuf75@yahoo.com

2. Objectives
• Protozoa
• Basic meaning
• 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 single cell 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 to organ of Locomotion
• Motile
–Pseudopodia
–Flagella
–Cilia
• Non-Motile
–Plasmodium species

5. Organ of Locomotion
Motility with 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 to Host Requirement
• Second Host not Required
–Entamoeba histolytica
–Giardia intestinalis
• Second Host not Required
–Trypanosoma cruzi
–Plasmodium vivax
–Leishmania donovani

8. Classification: Protozoa
According to Location/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
–Plasmodium species (RBC)
–Leishmania species (Monocyte)
–Trypanosoma species (Plasma)

10. Classification
• Intestinal protozoa
–Giardia lamblia (flagellate)
–Entamoeba histolytica (ameba)
–Cryptosporidium hominis (sporozoa)
–Cyclospora cayetanensis (sporozoa)
• Sexually transmitted protozoan
infection
–Trichomonas vaginalis (flagellate)

11. Classification
Blood and tissue protozoan infections
• Flagellates
–Trypanosoma
–Leishmania
• Amebae
–Entamoeba histolytica
–Naegleria fowleri
–Acanthamoeba castellanii

12. Classification
• Sporozoa
–Plasmodium Species
–Babesia microti
–Toxoplasma gondii
• Microsporidia

13. Important Protozoa
• Entamoeba histolytica
• Giardia lamblia
• Trichomonas vaginalis
• Leishmania Species
• Plasmodium Species
• Toxoplasma gondii

14. Entamoeba histolytica

15. Basic meaning and members
• Basic meaning of Entamoeba
–Enta means intestine
–amoeba means protozoa with
pseudopods

16. Member of the Genus
• Pathogenic
• Non-Pathogenic

17. Member of the genus
• Pathogenic
–Entamoeba histolytica (histo-tissue,
lytica-that lyze)

18. Member of the genus
Non-Pathogenic
Entamoeba coli
–coli-colon
–reside in colon
Entamoeba dispar
–dispar-disparity with E. histolytica

19. Non-Pathogenic Entamoeba
Entamoeba hartmanni
–Hartman is 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
• conversion of 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
Endoplasm contains
• Nucleus
• Food vacuoles
Food vacuoles contain
–bacteria or red blood cells
• Can’t get in stool examination

25. E.histolytica: trophozoite of E.histolytica with ingested erythrocytes of
Gomori‘s trichrome

26. E. histolytica: invasive trophozoites 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
• Infective stage/Form
–Mature Quadrinucleated Cyst
• Pathogenic stage
–Trophozoite
• Route of infection
–Feco-oral
• Site of lesion
–Large intestine

33. Life cycle
• Diagnostic stage
–Cyst in Stool
–Trophozoite in Liver Abscess

35. Spread of Infection
Mature cyst 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
• excystation occurs in Lumen of Caecum
–young trophozites come out
• Cysts can survive in environment for 12 to
30 days
–resistant to chemicals

38. Life Cycle
• Trophozoites live 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
• Galactose and 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 is facilitated by many factors like
– pore forming proteins
– Proteases
– Motility
– phagocytosis

43. Diseases Caused by E. histolytica
• Primary or Intestinal Lesion
–Acute amoebic dysentery (extensive
ulcers)
–Amoebic colitis/Chronic Intestinal
Amoebiasis
–Amoebomas

44. Diseases Caused by E. 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 are tumour-like lesions of the
colonic wall
• can measure up to several cm

46. Hall mark of amoebic 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
• Flask shaped 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 of Intestinal
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 of Hepatic
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 Pus of 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. Anchovy Fish/
Stolephorus commersonii

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
• Cerebral abscess
• Lungs abscess
• Liver abscess
• Splenic Abscess
• Amoebiasis cutis

58. Laboratory Diagnosis
Principle
• Specimen
• Microscopic Examination
• Culture
• Serology
• Molecular test

59. Basic Principles
• Microscopic demonstration 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
• Freshly passed stool
–Cyst

61. Diagnosis of Hepatic Amoebiasis
• Diagnostic aspiration
• Liver biopsy
• Exam of blood
• Exam of stool
• Serological tests
• Radiological exam
• Ultrasonography of Hepatobiliary system

62. Treatment
• Drug of choice 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 & Lab Differences 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. Thank You