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32 Cards in this Set
- Front
- Back
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Describe symptoms and geographical distribution of amoebic dysentery.
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Tropical areas, mostly
ulceration, inflammation, perforation of large intestine bloody, mucusy stools muscle wasting enlarged spleen |
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How and where does amoebic dysentery disseminate within the body?
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hematogeneous dissemination
intestines --> liver --> lungs --> brain large pus-filled abscesses, need drainage |
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Route of infection for amoebic dysentery?
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oral-fecal route: ingestion of cysts
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What percentage of amoebic dysentery remains subclinical?
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~80%
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What percentage of amoebic dysentery spreads to cause extraintestinal amoebiasis?
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~10%
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How is amoebic dysentery diagnosed?
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observe trophs/cysts in stool: 3 samples 48 hrs apart
mucus biopsy serology! for extraintestinal forms fecal antigen assays |
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What complicates diagnosis of amoebic dysentery?
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E. histolytica looks like E. dispar, a harmless commensal.
E. dispar 10x more abundant |
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What is the key microscopic difference between E. histolytica and other instestinal amoebae?
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E. histolytica does ERYTHROPHAGY
eats red blood cells. |
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What is characteristic about E. histolytica's movement and pseudopodia?
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unidirectional extrusion, finger-shaped pseudopodia
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Describe trophoziote of E. histolytica.
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12-60um, >20um invasive size
"clean" cytoplasm ONE nucleus w/chromatin margination small, central karyosome |
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Describe the cysts of E. histolytica.
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10-20um diam.
4 nuclei w/chromatin margination small central karyosome blunt chromatoidal bar |
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Describe the trophozoite phase of E. coli.
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15-50um
blunt pseudopodia, multidirectional dirty cytoplasm w/bacteria, yeast nucleus w/margination and small eccentric karyosome |
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Describe the cysts of E. coli.
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10-35um
up to 8 nuclei pointed chromatoidal bar |
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Describe the trophozoite phase of Endolimax nana.
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6-20um--smallest
nucleus w/no outline large, "blot" shaped karyosome many vacuoles in cytoplasm |
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Describe the trophozoite phase of Iodamoeba butschlii.
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4-20um across
many vacuoles w/ingested bacteria + yeasts nucleus w/no outline "basket nucleus:" bean shaped karyosome + crescent of fractured chromatin |
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Describe the trophozoite phase of Dientamoeba fragilis.
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NOT AN AMOEBA
5-15um 2 nuclei, no outline large fractured karyosome appearing as 4-8 dots within the nuclei |
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Describe the cysts of E. nana.
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5-10um
4 nuclei blotlike karyosomes no chromatoidal bar observed |
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Describe the cysts of I. butschlii.
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6-16um
**large glycogen vacuole one nucleus--no outline, blotlike karyosome |
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Describe the cysts of D. fragilis.
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no cyst phase.
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Describe cysts of Blastocystis hominis.
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6-40um (but usually 8-10um)
large central vacuole up to 6 small nuclei spherical to oval shape |
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Which free-living amoebae are pathogenic?
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Naegleria fowleri
Acanthamoeba spp. Balamuthia mandrillaris live in puddles, etc. |
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What diseases are caused by N. folweri?
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Primary amoebic meningoencephalitis (PAM)
troph, cyst, or flagellate can infect through nasal tract --> swiss cheese lesions in brain, growth of flagellates/trophs in CSF granulomatous lesions around blood vessels in brain |
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What diseases are caused by Acanthamoeba species?
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Skin Ulcers (immunocompromised pts)
Keratitis: inflammation/ulceration of cornea often spreads to brain via hematogeneous route. |
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Describe symptoms of Chronic Granulomatous Encephalitis by Acanthamoeba spp.
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granulomatous lesions in the brain tissue
spreads from lungs via hematogeneous route |
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How is PAM diagnosed?
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finding trophs/flagellates in CSF
wetmount/stain of CSF --> direct microscopy |
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How are Acanthamoeba infections diagnosed?
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brain/skin/cornea biopsy
culture of scrapings fluorescent antibody assays of samples |
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How can one prevent amoebiasis?
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wash your hands!
don't eat poop. wash fruits/veggies w/detergent to remove cysts boiling or iodination (NOT CHLORINATION) of water |
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What is the approximate incidence of Acanthamoebic keratitis?
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2-3 cases per million
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What is the etiology of Balantidiasis?
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Balantidium coli
ciliated protozoan big furry thing it invades your large intestine and does bad stuff |
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What is the natural reservoir of B. coli?
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swine/hogs
transmitted to humans if pig excrement used as crop fertilizer |
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Describe pathology of balantidiasis.
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-mostly asymptomatic
-invasion of colon lining similar to amoebiasis -no metastasis/extraintestinal invasion |
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How is balantidiasis diagnosed?
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-cysts/trophs in stool
-wet mount--but work fast! trophs disintegrate quickly. |
