Entamoeba histo

8/14/2019 Entamoeba histo

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Entamoebahistolytica


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BIOLOGY

Pseudopod-forming nonflagellaleted

Trophozoites highly motile Has pseudopodia Multiply by binary fission

Lacks organelles (resembles mitochondria)

No RER or Golgi apparatus

Mode of transmission Ingestion from fecally-contaminated material Venereal transmission through fecal-oral contact Direct colonial inoculation through contaminated enema

equipment


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CYSTS

-4 NUCLEI-CENTRALLYLOCATEDKARYOSOMES-FINE,UNIFORMLY

DISTRIBUTEDPERIPHERALCHROMATIN.-MEASURE 12 TO15 M.


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LIFE CYCLE


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PATHOGENESIS AND CLINICAL MANIFESTATIONIN HUMANS

Pathogenic

infection can lead to amoebic dysentery or

amoebic liver abscess

Symptoms can include fulminating dysentery

bloody diarrheaweight loss

fatigue

abdominal pain


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asymptomatic infection ("luminal amebiasis)

invasive intestinal amebiasis (dysentery,colitis, appendicitis, toxic megacolon,amebomas)

invasive extraintestinal amebiasis (liverabscess, peritonitis, pleuropulmonaryabscess, cutaneous and genital amebiclesions)


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DIAGNOSIS OF INFECTION

Infective stage : Quadrinucleated cyst(having 4 nuclei)

Diagnostic stage : trophozoite

Direct Fecal Smear (DFS) and staining

Enzyme immunoassay (EIA); IndirectHemagglutination (IHA); Antigen detection monoclonal antibody andPCR


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Iodamoebabtschlii


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BIOLOGY

Cysts vary from being nearly spherical to ellipsoidal

measure 5-20 m

single nucleus that is not visible in eitherunstained or iodine-stained wet mounts

With permanent stains (such as trichrome), thenucleus contains a large, usually eccentrickaryosome

presence of a large compact mass (vacuole)of glycogen in the cyst stage.


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Trophozoites

measure 8 to 20 m

single nucleuswith a large

usually central karyosome

surrounded by refractile, achromatic

granules.Cytoplasm

coarsely granular

Vacuolated

can contain bacteria, yeasts or othermaterials.

Movement in living trophozoites is sluggish anddescribed as nonprogressive.


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LIFE CYCLE


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PATHOGENESIS AND CLINICAL MANIFESTATIONIN HUMANS

Non-pathogenic

Causes amebiasis in immunologically

compromised individuals


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Infected form: Mature, uninucleated cysts

identification is made by observing cysts

and/or trophozoites in stool specimens, bothconcentrated wet mounts and permanentstained smears.


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Naegleria fowleri


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BIOLOGY

does not form cysts in human tissues

two forms of trophozoites Ameboid(trophozoite form) Ameboflagellate (swimming form)

Ameboid measure 10-35 m but when rounded are usually 10-15 m in diameter

In culture, trophozoites may get over 40 m

cytoplasm is granular and contains many vacuoles

Nucleus Single large and has a large, dense karyosome lacks peripheral chromatin


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Flagellate small pear-shaped

with two long whip-like flagellae at one end

very mobile stage that infects people

Amoeba

slow moving single-celled organism thatproliferates by dividing repeatedly.

Returned to water, and occasionally in humanspinal fluid, the amoeba will once again assumethe flagellate form.

Cyst tough spherical stage found only in the

environment, forms when conditions areunfavorable for naegleria.


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LIFE CYCLE


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PATHOGENESIS AND CLINICAL MANIFESTATION IN HUMANS

Acute primary amebic meningoencephalitis(PAM) severe headache

other meningeal signs

Fever

vomiting

focal neurologic deficits

progresses rapidly (


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microscopic examination of cerebrospinalfluid (CSF).

Wet mount may detect motile trophozoites,and a Giemsa-stained smear will showtrophozoites with typical morphology

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Entamoeba histo