溶组织内阿米巴 Entamoeba histolytica

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溶组织内阿米巴 Entamoeba histolytica Powered By Docstoc
					 溶组织内阿米巴
 溶组织内阿米巴
Entamoeba histolytica

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   流   实致生形前
   行   验病活态言
   与   诊 史
   防   断
   治
   山东大学寄生虫学教研室
       何深一
           Introduction
    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 histolytica
         Entamoeba dispar
   Major pathogen
    – world-wide distribution (10%)
    – 5% in some developed countries
    – 100 deaths in Chicago 1930
   Trophozoite & Cyst
    – oral-faecal transmission
              Morphology

   Pay your attention to stages that have
    diagnostic value
    Parasites stained with hematoxylin is
    described here.
    Trophozoite (active form)
 (1) Size: 10-40 micrometers in diameter, some
  are above 60 micrometers.
 (2) Pseudopodium(ectopalsmic protrusion):
    A. broad or finger-like in form
    B. thrust out quickly
    C. firstly, formed with ectoplasm, secondly,
  endoplasm flows slowly into it.
    D. motility is progressive and directional.
    Trophozoite (active form)
 (3) Endoplasm: red blood cells may be found in
     it.
 (4) Nucleus (vesicular type)
      It is not visible in an unstained specimen;
      but its clear structure can be seen when
      stained with hematoxylin.
   A: membrane: distinct line
   B: chromatin granules: fine and uniformly
       arranged in the inner surface of the
       nuclear membrane.
   C: karyosome: small and centrally located.
Phase contrast photomicrograph of cultured
   Entamoeba histolytica trophozoites.
         Charcot 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 E. histolytica
     进行性和定向阿米巴运动
      progressive and directional
         Cyst (non-motile)
  (1) 10-20 mocrometers in size
 (2) spherical in shape
 (3) 1-2 nuclei (immature cyst); 4 nuclei (mature
  cyst-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 coli
 Gut commensal
 Trophozoite & cyst
 Slow “lazy” movement
 Oral-faecal transmission
           E. histolytica v E. coli
   Trophozoite
    – 10-40um                  – 15-30um
    – delicate nuclear         – coarse nuclear
      structure                  structure
   Cyst
    – 9.5-15.5um               – 10-30um
    – 4 nuclei                 – 8 nuclei
    – Broad, blunt chromatid   – thin, sharp chromatid
      bodies                     bodies
Entamoeba coli
Entamoeba coli
               Life Cycle

 1 infective stage: mature cyst
 2 access: mouth
 3 ecological niches: large intestine; liver,
  lung and other organs.
 4 pathogenic stage: trophozoite
 5 diagnostic stage: cyst; trophozoites
       Pathogenic factors

 1. Toxicity of parasites pathogenic-
        nonpathogenic complex.
    Entamoeba histolytica
     Entamoeba dispar
 2. Symbiotic bacteria
 3. Defence barrier immunity
                                                             This  cytolytic
                                                             event is a result of
                                                             incorporation in
                                                             the host cell
                                                             membrane of an
                                                             ameba-produced,
                                                             pore-forming
                                                             protein,
                                                             Amoebapore.




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.
        Pathology and
    Clinical Manifestation
 Pinpoint lesion on mucous membrane
 Flask-shaped crateriform ulcers
       Clinical classification
 Asymptomatic infection (carrier) >90%
  cases (E. dispar?)
 Sympomatic cases <10%
    – 8-10% dysentery, colitis, etc
    – 2% invasive amoebiasis
    – 0.1% deaths
    A. Intestinal amoebiasis
 a. dysentery: dysenteric stools (pus and blood
 without feces). fever, dehydration, and electrolyte
 abnormalities. Tenesmus and abdominal
 tenderness.
 b. non-dysenteric colitis
 c. appendicitis
 d. amoeboma:may become the leading point of
 an intussusception or may cause intestinal
 obstruction.
 Histopathology of a typical flask-
shaped ulcer of intestinal amebiasis
      A Micro Abscess in the
           submucosa .
   Containing a large
    number of E.
    histolytica
    trophozoites mostly
    at the periphery .H
    and E. ×400.
    Enlarged by 5.4.
         B. Extra-intestinal
            amoebiasis

  a. Hepatic
   (1) acute non-suppurative
   (2) liver abscess: right upper quadrant
  pain, referred to the right shoulder. tender.
 b. Pulmonary
         B. Extra-intestinal
            amoebiasis

   c. Brain
   d. Skin, perianal infection
   e. Other extra-intestinal amoebiasis
Amoebic Liver Abscess
Gross pathology of liver containing
        amebic abscess
Gross pathology of amebic abscess of liver. Tube of
         "chocolate" pus from abscess.
    An Amoebic Liver Abscess
        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
            Abscess.

A   fluid level
  has formed
  after aspiration
  due to entry of
  air
                        Diagnosis
1.Stool examination
                  trophozoite                     cyst

                     feces                       feces
specimen


method     direct smear with normal   direct smear with iodine
           saline                     stain

diseases                              chronic intestinal
           amoebic dysentery
                                      amoebiasis or carriers
           1.container must clean
           2.examined soon after they 4.keep specimen warm.
remarks
           have been passed.
           3.select bloody and        5.drug using histry.
           mucous portion.
               Diagnosis

 2. Serologic studies: indirect
  hemagglutination, skin tests, ELISA and
  latex agglutination.
 3. Tissue examination: sigmoidoscopic
  biopsy, aspiration
 4. DNA probe
              Epidemiology

   Distribution: all climates, arctic to tropical.
    Media: flies; black beetles etc.
    Treatment and Prevention

 Treatment:
 Diodoquin-carriers
 Metronidazole-dysentery, liver abscess
              Prevention

 Human feces should not be used as fertilizer
 Food and drinks must be protected from
  flies
 Personal hygiene: wash hands after
  defecation and before meals.

				
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posted:4/29/2013
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