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溶组织内阿米巴溶组织内阿米巴
前言 前言
形态 形态
生活史
生活史
致病
致病
实验诊断
实验诊断
流行与防治
流行与防治
溶组织内阿米巴溶组织内阿米巴 Entamoeba histolyticaEntamoeba histolytica
山东大学寄生虫学教研室山东大学寄生虫学教研室 何深一何深一
IntroductionIntroduction
1. The only pathogenic amoeba among all of the intestinal amoebae 2. Infecting perhaps 10% of the world's population. 3. Lead to invasive amoebiasis.
Entamoeba histolyticaEntamoeba histolyticaEntamoeba disparEntamoeba dispar
Major pathogen– world-wide distribution (10%)– 5% in some developed countries– 100 deaths in Chicago 1930
Trophozoite & Cyst– oral-faecal transmission
MorphologyMorphology
Pay your attention to stages that have diagnostic valueParasites stained with hematoxylin is described here.
Trophozoite (active form)Trophozoite (active form)
(1) Size: 10-40 micrometers in diameter, some a(1) Size: 10-40 micrometers in diameter, some are above 60 micrometers.re above 60 micrometers.
(2) Pseudopodium(ectopalsmic protrusion):(2) Pseudopodium(ectopalsmic protrusion): A. broad or finger-like in form A. broad or finger-like in form B. thrust out quickly B. thrust out quickly C. firstly, formed with ectoplasm, secondly, C. firstly, formed with ectoplasm, secondly, endoplasm flows slowly into it.endoplasm flows slowly into it. D. motility is progressive and directional. D. motility is progressive and directional.
Trophozoite (active form)Trophozoite (active form)
(3) Endoplasm: red blood cells may be found in (3) Endoplasm: red blood cells may be found in it.it. (4) Nucleus (vesicular type)(4) Nucleus (vesicular type)
It is not visible in an unstained specimen; It is not visible in an unstained specimen; but its clear structure can be seen when but its clear structure can be seen when stained with hematoxylin.stained with hematoxylin.
A: membrane: distinct line A: membrane: distinct line B: chromatin granules: fine and uniformly B: chromatin granules: fine and uniformly
arranged in the inner surface of the arranged in the inner surface of the nuclear membrane.nuclear membrane.
C: karyosome: small and centrally located. C: karyosome: small and centrally located.
Phase contrast photomicrograph of cultured Phase contrast photomicrograph of cultured
Entamoeba histolytica trophozoites. Entamoeba histolytica trophozoites.
Charcot Leyden CrystalCharcot Leyden Crystal These diamond shaped
crystals are often seen in amoebic dysentery faeces and may also be present in other parasitic infections. They are absent in bacillary dysentery. Interference contrast. ×400. Enlarged by 9.6
Movement of Movement of E. histolyticaE. histolytica 进行性和定向阿米巴运动
progressive and directionalprogressive and directional
Cyst (non-motile)Cyst (non-motile)
(1) 10-20 mocrometers in size (2) spherical in shape (3) 1-2 nuclei (immature cyst); 4 nuclei (mature cy
st-infective stage). (4) inclusions:(become smaller and smaller as the
cyst ages) glycogen vacuole appears as a clear space; food reservoir chromatoid body dark blue rods or dots; its function is not known
The single nucleus with its central endosome and regularly distributed chromatin is visible. The dark "rods" in the cytoplasm are the chromatoid bars; approximate size = 18 µm.
This is a mature cyst and contains four nuclei. However, only two nuclei are visible in this plane of focus, and a chromatoid bar is still present; approximate size = 17 µm.
Entamoeba coliEntamoeba coli
Gut commensalTrophozoite & cystSlow “lazy” movementOral-faecal transmission
E. histolytica v E. coliE. histolytica v E. coli
Trophozoite– 10-40um– delicate nuclear
structure
Cyst– 9.5-15.5um– 4 nuclei– Broad, blunt chromatid
bodies
– 15-30um– coarse nuclear
structure
– 10-30um– 8 nuclei– thin, sharp chromatid
bodies
Entamoeba coliEntamoeba coli
Entamoeba coliEntamoeba coli
Life CycleLife Cycle
1 infective stage: mature cyst2 access: mouth3 ecological niches: large intestine; liver, l
ung and other organs.4 pathogenic stage: trophozoite5 diagnostic stage: cyst; trophozoites
Pathogenic factorsPathogenic factors
1. Toxicity of parasites pathogenic-
nonpathogenic complex. Entamoeba histolytica
Entamoeba dispar2. Symbiotic bacteria3. Defence barrier immunity
This protein forms ion channels in lipid cell membranes and results in cell death within minutes of cell contact with the ameba. Amoebapore has been isolated, synthesized and well characterized. Non-pathogenic strains of E. histolytica can also produce amoebapore but are much less efficient at its production and the molecule is not exactly similar to that produced by virulent strains.
This cytolytic event is a result of incorporation in the host cell membrane of an ameba-produced, pore-forming protein, Amoebapore.
Pathology and Pathology and Clinical ManifestationClinical Manifestation
Pinpoint lesion on mucous membraneFlask-shaped crateriform ulcers
Clinical classificationClinical classification
Asymptomatic infection (carrier) >90% cases (E. dispar?)
Sympomatic cases <10%– 8-10% dysentery, colitis, etc– 2% invasive amoebiasis– 0.1% deaths
A. Intestinal amoebiasisA. Intestinal amoebiasis
a. dysentery:a. dysentery: dysenteric stools (pus and blood without feces). fever, dehydration, and electrolyte abnormalities. Tenesmus and abdominal tenderness.
b. non-dysenteric colitisb. non-dysenteric colitis c. appendicitisc. appendicitis d. amoeboma:d. amoeboma:may become the leading point of may become the leading point of
an intussusception or may cause intestinal obstan intussusception or may cause intestinal obstruction. ruction.
Histopathology of a typical flask-shapHistopathology of a typical flask-shaped ulcer of intestinal amebiasis ed ulcer of intestinal amebiasis
A Micro Abscess in the submucA Micro Abscess in the submucosa .osa .
Containing a large number of E. histolytica trophozoites mostly at the periphery .H and E. ×400. Enlarged by 5.4.
B. Extra-intestinal amoebiasB. Extra-intestinal amoebiasisis
a. Hepatic (1) acute non-suppurative (2) liver abscess: right upper quadrant pa
in, referred to the right shoulder. tender. b. Pulmonary
B. Extra-intestinal amoebiasB. Extra-intestinal amoebiasisis
c. Brain d. Skin, perianal infection e. Other extra-intestinal amoebiasis
Amoebic Liver AbscessAmoebic Liver Abscess
Gross pathology of liver containing Gross pathology of liver containing
amebic abscessamebic abscess
Gross pathology of amebic abscess of liver. Tube of Gross pathology of amebic abscess of liver. Tube of "chocolate" pus from abscess. "chocolate" pus from abscess.
An Amoebic Liver Abscess An Amoebic Liver Abscess Being Aspirated.Being Aspirated.
Note the reddish brown color of the pus (‘anchovy-sauce’). This color is due to the breakdown of liver cells. Enlarged by 5.4
X-ray of a Large Amoebic Liver X-ray of a Large Amoebic Liver Abscess.Abscess.
A fluid level has formed after aspiration due to entry of air
DiagnosisDiagnosis1.1.Stool examinationStool examination
trophozoite cyst
specimenfeces feces
method direct smear with normal saline
direct smear with iodine stain
diseases amoebic dysenterychronic intestinal amoebiasis or carriers
remarks
1.container must clean2.examined soon after they have been passed.3.select bloody and mucous portion.
4.keep specimen warm.
5.drug using histry.
DiagnosisDiagnosis
2. Serologic studies: indirect hemagglutination, skin tests, ELISA and latex agglutination.
3. Tissue examination: sigmoidoscopic biopsy, aspiration
4. DNA probe
EpidemiologyEpidemiology
Distribution: all climates, arctic to tropical. Media: flies; black beetles etc.
Treatment and PreventionTreatment and Prevention
Treatment:Treatment:Diodoquin-carriersMetronidazole-dysentery, liver abscess
PreventionPrevention
Human feces should not be used as fertilizerFood and drinks must be protected from
fliesPersonal hygiene: wash hands after
defecation and before meals.