AMOEBA Flashcards
amoeba move through __
pseudopodia
•motile
•reproducing
•feeding stage
trophozoite
•non-motile
•non-feeding stage
•infective stage to humans
cysts
transmission of amoeba is generally by
ingestion of cyst
-cause dysentery
-nucleus karyosome or endosome
-mostly with RBC in cytoplasm
-the cyst of this has chromatoid bars (rounded)
entamoeba histolytica
• Nonpathogenic
• Size: cyst = < 10um, trophozoite = < 12 um
entamoeba hartmanni
•Cysts and trophozoites are morphologically
identical to E. histolytica
•noninvasive
•never ingests RBCs
Entamoeba dispar
Transmission (Entamoeba histolytica)
• The infection can be transmitted sexually by homosexual males and is
one cause of the disease known as
gay bowel syndrome
• Nonpathogenic
• Commonly confused with E. histolytica
Entamoeba coli
• nonpathogenic
• found primarily in pigs and monkeys
• Occasionally in humans
• resembles both E. histolytica and E. coli morphologically
Entamoeba polecki
•Nonpathogenic
•found in:
• mouth in soft tartar between teeth or in tonsillar crypts
• Occasionally in sputum
• no cyst stage
• only species to ingest white blood cells.
• (fragments in large vacuole)
Entamoeba gingivalis
irregular dump karyosome with no peripheral chromatin
Endolimax nana
large irregular karyosome with no peripheral chromatin
lodamoeba bütschlii
• strictly anaerobic intestinal protozoa
• Reproduction:
• binary fission or sporulation
• Fecal-oral transmission through contaminated food or water
• Metronidazole -treatment is needed.
• size and shape:
• Round
• from 6 to 40 µm in diameter.
• confused with yeast cells
Blastocystis hominis
• May become opportunistic parasites to humans
•found in fresh or salt water, moist soil, and decaying
vegetation.
• In most instances, no disease is produced by these
organisms. In a few cases, however, severe
consequences result.
• The notable potential pathogens are Naegleria fowleri
and, less commonly, Acanthamoeba spp.
free-living amebae
• Ameboflagellate (ONLY ameboid phase found in host tissues)
• Entry: through the nasal mucosa (swimming, diving)
• It then migrates along the olfactory nerves and, within several days,
invades the brain.
• highly thermophilic
• survives at water temperatures up to 113ºF.
• tolerates chlorinated water
Naegleria fowler
• Atleast 6 species cause granulomatous amebic encephalitis
(GAE)
• isolated from the upper respiratory tract (healthy individual)
• grow best in the upper airways of susceptible patients
• Infections:
• inhalation of contaminated dust or aerosols
• invasion of broken skin or mucous membranes.
• found in the lungs, nasal and sinus passages, eyes, ears, skin
lesions, and vagina
Acanthamoeba spp.
•related to poor contact lens care
•Direct examination of a patient’s cornea using a
confocal microscope can aid in diagnosing
• Direct examination and culture of corneal scrapings can
also lead to a correct diagnosis.
•Using contaminated saline cleaning solutions and
wearing lenses while swimming in contaminated
water are the usual causes of these infections.
Acanthamoeba keratitis
• another causative agent of GAE
• It has also been found in immunocompetent children.
• This parasite has been found in many primates (e.g., gorillas, gibbons,
monkeys) and sheep and horses.
• One-third of the few cases reported in the United States were in
patients with AIDS
Balamuthia mandrillaris
• resistant to chlorination and drying
• trophozoites:
• spinelike pseudopodia but are rarely seen motile
• 30 µm
• have a large central karyosome in the nucleus.
• cysts:
• T10- to 25-µm
• round with a single nucleus and has a double wall;
• the outer cyst wall may be slightly wrinkled with a polyhedral inner
wall.
Acanthamoeba spp.
