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 Amoeba are structurally simple protozoans
which have no fixed shape
 Phylum : Sarcomastigophora
 Subphylum :Sarcodina
...
Amoeba
Free living
Intestinal
 Entamoeba histolytica is an intestinal
amoeba
 All intestinal amoebae are non pathogenic...
 E. histolytica was discovered by Losch in
1875
 Demonstrated the parasite in the dysenteric
feces of a patient in St.Pe...
 MORPHOLOGY
 LIFE CYCLE
 PATHOGENESIS & CLINICAL FEATURES
 LABORATORY DIAGNOSIS
 TREATMENT
 PREVENTION
 E.histolytica occurs in 3 forms
Trophozoite
Precyst
Cyst
 Vegetative or growing stage of the parasite
 Only form present in tissues
 Irregular in shape
 Size: 12-60 μm( Averag...
Cytoplasm
Outer ectoplasm-clear,transparent,
refractile.
Inner endoplasm-finely granular
(ground glass appearance),with
nu...
 Pseudopodia
Fingerlike projections formed by
sudden jerky movements of ectoplasm in one
direction, followed by the strea...
Nucleus
 It is spherical 4-6μm in size
 contains central karyosome,surrounded by
clear halo and anchored to the nuclear
...
 Trophozoites from acute dysentric stools
often contain phagocytosed erythrocytes-
diagnostic feature ,these are not foun...
 Trophozoites undergo encystment in the
lumen
 Before encystment,the trophozoites
extrudesits food vacuoles and become r...
 Spherical ,10-20µm
 3 types of cyst
Early cyst
Binucleate cyst
mature quadrinucleate cyst
Early cyst
contains a single ...
 As the cyst mature, the glycogen mass and
chromidial bars disappear and the nucleus
undergoes 2 succesive mitotic divisi...
 Infective form :mature quadrinucleate cyst
passed in feces of convalscents and carriers
 Mode of transmission :man acqu...
 E.histolytica causes intestinal and extra
intestinal amoebiasis
Intestinal amoebiasis -PATHOGENESIS
Lumen dwelling amoeb...
 Not all strains of E.histolytica are pathogenic or
invasive .
 Differentiation between pathogenic and non
pathogenic st...
 The metacystic trophozoites penetrate the columnar
epithelial cells of crypts of Liberkuhn
 Penetration is facilitated ...
 Ulcer appear initially on the mucosa as raised
nodules with pouting edges .
 They breakdown discharging brownish
necrot...
 The ulcers generally do not extend deeper
than submucosal layer.
 Occassionally, a granulamatous
pseudotumoral growth m...
 Small superficial ulcers involving only the mucosa
 Round or oval shaped with ragged and undermined margin
and flask-sh...
 The incubation period is highly variable from
1-4 months
 The clinical course is characterized by
prolonged latency,rel...
 The RBCs in stools are clumped and reddish
brown in color.
 Cellular exudate is scanty.
 Charcot-leyden crystals are o...
 Intestinal amoebiasis not always result in
dysentry.quite often there may be only
diarrhea or vagueabdominal symptoms
po...
 Fulminant amoebic colitis
toxic megacolon
perianal ulceration
Amoeboma
 Extra intestinal Amoebiasis
amoebic hepatitis
a...
 Hepatic Amoebiasis
 Pulmonary Amoebiasis
 Metastatic Amoebiasis
 Cutaneous Amoebiasis
 Genitourinary Amoebiasis
 Most common extra intestinal amoebiasis .
 The history of amoebic dysentry is absent in
more than 50% cases
 Several p...
 In about 5-10% of person with intestinal
amoebiasis ,liver abscesses may ensue.
 The center of the abscess contains thi...
 Usually located on right lobe of liver
 Jaundice develops
only when lesions are multiple OR
when they press on the bili...
 It may occure by direct hematogenous spread
from colon bypassing the liver,but it most
often follows extension of hepati...
 Involvement of distant organs is by
hematogenous spread and through
lymphatics
 Abscess in
Kidney
Brain
Spleen
Adrenals...
 It occurs by direct extension around anus,
colostomy site,or discharging sinuses from
amoebic abscess .
 Extensive gang...
 Penile amoebiasis
prepuce and glans are affected
acquired through anal intercourse
In females
 vulva ,vagina, or cervix...
THANK YOU
Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica
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Entamoeba histolytica

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Microbiology

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Entamoeba histolytica

  1. 1.  Amoeba are structurally simple protozoans which have no fixed shape  Phylum : Sarcomastigophora  Subphylum :Sarcodina  Super class :Rhizopoda  Order : Amoebida
  2. 2. Amoeba Free living Intestinal  Entamoeba histolytica is an intestinal amoeba  All intestinal amoebae are non pathogenic except Entamoeba histolytica  All free living amoeba are oppurtunistic pathogens.
  3. 3.  E. histolytica was discovered by Losch in 1875  Demonstrated the parasite in the dysenteric feces of a patient in St.Petersburg in Russia.
  4. 4.  MORPHOLOGY  LIFE CYCLE  PATHOGENESIS & CLINICAL FEATURES  LABORATORY DIAGNOSIS  TREATMENT  PREVENTION
  5. 5.  E.histolytica occurs in 3 forms Trophozoite Precyst Cyst
  6. 6.  Vegetative or growing stage of the parasite  Only form present in tissues  Irregular in shape  Size: 12-60 μm( Average 20μm)  Large and actively motile in freshly passed dysenteric stool, while smaller in convalescents and carriers.  In the lumen, commensal and small in size(15-20 μm)-MINUTA FORM
  7. 7. Cytoplasm Outer ectoplasm-clear,transparent, refractile. Inner endoplasm-finely granular (ground glass appearance),with nucleus food vacuoles erythrocytes leucocytes(occasionally) tissue debris
  8. 8.  Pseudopodia Fingerlike projections formed by sudden jerky movements of ectoplasm in one direction, followed by the streaming in of the whole endoplasm  Typical amoeboid motility is a Crawling or Gliding  Pseudopodia formation and motility are inhibited at low temperature
  9. 9. Nucleus  It is spherical 4-6μm in size  contains central karyosome,surrounded by clear halo and anchored to the nuclear membrane by fine radiating fibrils called the Linin network , giving a cartwheel appearance  Nuclear membrane is lined by a rim of chromatin distributed evenly as small granules
  10. 10.  Trophozoites from acute dysentric stools often contain phagocytosed erythrocytes- diagnostic feature ,these are not found in any other commensal intestinal amoeba  These divided by binary fission in every 8 hours  These are killed by drying, heat ,and chemical sterilization  Infections are not transmitted by these- destroyed in stomach and cannot initiate infection
  11. 11.  Trophozoites undergo encystment in the lumen  Before encystment,the trophozoites extrudesits food vacuoles and become round or oval,10-20µm in size-precyst  Contains a large glycogen vacuole and two chromatid bars  It then secretes a highly retractile cyst wall around it and become cyst
  12. 12.  Spherical ,10-20µm  3 types of cyst Early cyst Binucleate cyst mature quadrinucleate cyst Early cyst contains a single nucleus and two other structures-a mass of glycogen and 1-4 chromatid bodies or chromadial bars
  13. 13.  As the cyst mature, the glycogen mass and chromidial bars disappear and the nucleus undergoes 2 succesive mitotic divisions to form 2 and then 4 nuclei .  The cyst wall is a highly resistant to gastric juice and unfavorable environmental conditions
  14. 14.  Infective form :mature quadrinucleate cyst passed in feces of convalscents and carriers  Mode of transmission :man acquires infection by swallowing food and water contaminated with cyst .  Stomach –cyst wall is resistant to gastric juice  Exystation :cyst reaches the caecum or lower part of ileum ,due to alkaline medium ,cyst wall damaged by trypsin ,leading to exystation
  15. 15.  E.histolytica causes intestinal and extra intestinal amoebiasis Intestinal amoebiasis -PATHOGENESIS Lumen dwelling amoeba do not cause any illness .They causes disease only when they invade the intestinal tissues . 10 % -symptomatic 90% -asymptomatic
  16. 16.  Not all strains of E.histolytica are pathogenic or invasive .  Differentiation between pathogenic and non pathogenic strains can be made by  susceptibility to complement-mediated lysis  Phagocytic activity  by the use of genetic markers  monoclonal antibodies  Zymodeme analysis
  17. 17.  The metacystic trophozoites penetrate the columnar epithelial cells of crypts of Liberkuhn  Penetration is facilitated by motility of the trophozoites tissue lytic enzyme –histolysin amoebic lectin -mediate adherence  Mucosal penetration by amoeba produce discrete ulcers with pinhead center and raised edges .  Sometimes invasion remains superficial and heal spontaneously.  More often, the amoeba penetrates to submucosal layer and multiplies rapidly- lytic necrosis- abscess- ulcer
  18. 18.  Ulcer appear initially on the mucosa as raised nodules with pouting edges .  They breakdown discharging brownish necrotic material contains large numbers of trophozoites.  The typical amoebic ulcer –flask shaped  Multiple ulcers may coalesce to form large necrotic lesions with ragged and undermined edges,covered with brownish slough
  19. 19.  The ulcers generally do not extend deeper than submucosal layer.  Occassionally, a granulamatous pseudotumoral growth may develop on the intestinal wall from a chronic ulcer.This amoebic granuloma or amoeboma may be mistaken for are malignant tumor
  20. 20.  Small superficial ulcers involving only the mucosa  Round or oval shaped with ragged and undermined margin and flask-shaped in cross section  Marked scarring of intestinal wall with thining ,dilatation ,and sacculation  Extensive adhesions with neighboring viscera  Formation of tumor-like masses of granulation tissue amoeba
  21. 21.  The incubation period is highly variable from 1-4 months  The clinical course is characterized by prolonged latency,relapses and intermissions.  Typical manifestation is amoebic dysentry  Compared to bacillary desentry ,it is usually insidious in onset and the abdominal tenderness is less and localised.  The stools are large, foul-smelling,and brownish black, often with bloodstreaked mucus intermingled with feces.
  22. 22.  The RBCs in stools are clumped and reddish brown in color.  Cellular exudate is scanty.  Charcot-leyden crystals are often present.  The patient is usually afebrile and non toxic.  In fulminant colitis, there is confluent ulceration and necrosis of colon-patient is febrile and toxic.
  23. 23.  Intestinal amoebiasis not always result in dysentry.quite often there may be only diarrhea or vagueabdominal symptoms popularly called uncomfortable belly or growling abdomen.  Chronic involvement of the caecum causes a condition simulating appendicitis.
  24. 24.  Fulminant amoebic colitis toxic megacolon perianal ulceration Amoeboma  Extra intestinal Amoebiasis amoebic hepatitis amoebic liver abscess amoebic appendicitis and peritonitis pulmonary amoebiasis cerebral amoebiasis splenic abscess cutaneous amoebiasis genitourinary amoebiasis
  25. 25.  Hepatic Amoebiasis  Pulmonary Amoebiasis  Metastatic Amoebiasis  Cutaneous Amoebiasis  Genitourinary Amoebiasis
  26. 26.  Most common extra intestinal amoebiasis .  The history of amoebic dysentry is absent in more than 50% cases  Several patients with amoebic colitis develop an enlarged tender liver without detectable impairment of liver function or fever.  This acute hepatic involvement (amoebic hepatitis) may be due to repeated invasion by amoeba from an active colonic infection or to toxic substance from the colon reaching the liver.
  27. 27.  In about 5-10% of person with intestinal amoebiasis ,liver abscesses may ensue.  The center of the abscess contains thick chocolate brown pus(anchovy pus),which is liqeefied necrotic liver tissue.  At the periphery, there is almost normal liver tissue,which contain invading amoeba.  Liver abscess may multiple solitary
  28. 28.  Usually located on right lobe of liver  Jaundice develops only when lesions are multiple OR when they press on the biliary tract  Incidenca of liver abscess is less common in women and rare in children under age of 10
  29. 29.  It may occure by direct hematogenous spread from colon bypassing the liver,but it most often follows extension of hepatic abscess through the diaphragm  Hepatobronchial fistula usually results with expectoration of chocolate brown sputum  Patient presents with severe pleuritic chest pain dyspnea non-productive cough
  30. 30.  Involvement of distant organs is by hematogenous spread and through lymphatics  Abscess in Kidney Brain Spleen Adrenals Spread to brain leads to severe destruction of brain tissues and is fatal
  31. 31.  It occurs by direct extension around anus, colostomy site,or discharging sinuses from amoebic abscess .  Extensive gangrenous destruction of the skin occurs .  The lesion may be mistaken for condyloma or epithelioma
  32. 32.  Penile amoebiasis prepuce and glans are affected acquired through anal intercourse In females  vulva ,vagina, or cervix  by spread from perineum  destructive ulcerative lesions resemble carcinoma
  33. 33. THANK YOU

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