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Questions and Answers
Match the parasite with its characteristic size range for trophozoites:
Match the parasite with its characteristic size range for trophozoites:
Endolimax nana = 8 to 12μm Entamoeba histolytica = 12 to 55μm Entamoeba polecki = 18 to 27μm Entamoeba hartmanni = 12 to 55μm
Match the parasite with its characteristic motility for trophozoites:
Match the parasite with its characteristic motility for trophozoites:
Entamoeba coli = Sluggish, nonprogressive Entamoeba gingivalis = Rapid and jerky Acanthamoeba species = Flagellated Naegleria fowleri = Ciliated
Match the parasite with the description of its cysts:
Match the parasite with the description of its cysts:
Entamoeba histolytica = Thick cell wall surrounds the round to spherical cyst Entamoeba polecki = Thin delicate cyst wall Iodamoeba butschlii = Usually uninucleate Endolimax nana = One to eight nuclei with typical nuclear features
Match the parasite with its typical life cycle location in stool:
Match the parasite with its typical life cycle location in stool:
Match the parasite with its pathogenicity status:
Match the parasite with its pathogenicity status:
Match the parasite with its importance in medical diagnosis:
Match the parasite with its importance in medical diagnosis:
Match the following characteristics with Entamoeba histolytica:
Match the following characteristics with Entamoeba histolytica:
Match the following parasites with their size range in micrometers:
Match the following parasites with their size range in micrometers:
Match the following characteristics with Acanthamoeba species:
Match the following characteristics with Acanthamoeba species:
Match the following parasites with their clinical significance:
Match the following parasites with their clinical significance:
Match the following parasites with their characteristics related to pseudopods:
Match the following parasites with their characteristics related to pseudopods:
Match the following parasites with their treatment options:
Match the following parasites with their treatment options:
Match the following amoeba with their characteristics:
Match the following amoeba with their characteristics:
Match the following amoeba with their sizes:
Match the following amoeba with their sizes:
Match the following amoeba with their life cycle stages:
Match the following amoeba with their life cycle stages:
Match the following amoeba with their treatment options:
Match the following amoeba with their treatment options:
Match the following amoeba with their clinical symptoms:
Match the following amoeba with their clinical symptoms:
Match the following amoeba with their motility characteristics:
Match the following amoeba with their motility characteristics:
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Study Notes
Phylum Sarcomastigophora
- Amoeba is a single-celled protozoa that constantly changes its shape due to the presence of pseudopodia.
- The word "amoeba" is derived from the Greek word "amoibe," meaning "change."
Entamoeba histolytica
- Discovered by Loschin in 1875.
- Found in the dysenteric feces of a patient in St. Petersburg, Russia.
- Named and differentiated from E. coli by Fritz Schaudinn.
- Anaerobic parasitic amoebozoan that infects humans and other primates, causing amoebiasis.
- Estimated to infect about 50 million people worldwide.
Morphology of Entamoeba histolytica
- Trophozoites:
- Range in size from 12 to 60μm, with an average size of 12 to 25μm.
- Exhibit rapid, unidirectional, progressive movement.
- Have finger-like hyaline pseudopods.
- Single nucleus contains a small karyosome.
- Cysts:
- Spherical to round in shape.
- Smaller than trophozoites, measuring 8 to 22μm, with an average range of 12 to 18μm.
Laboratory Diagnosis and Clinical Significance
- Stool examination for trophozoites and cysts.
- Asymptomatic infections are common.
- Treatment: nitroimidazole for intestinal infection, metronidazole and chloroquine for liver abscess.
Entamoeba coli
- Nonpathogenic species of Entamoeba.
- Frequently exists as a commensal parasite in the human gastrointestinal tract.
- Can be confused with Entamoeba histolytica during microscopic examination.
Morphology of Entamoeba coli
- Trophozoites:
- Measure between 18 to 27μm, with some as small as 12μm and others as large as 55μm.
- Equipped with blunt pseudopods.
- Exhibit sluggish, nonprogressive motility.
- Cysts:
- Vary in size from 8 to 35μm, with an average of 12 to 25μm.
- Thick cell wall surrounds the round to spherical cyst.
- One to eight nuclei with typical nuclear features.
Life Cycle of Entamoeba coli
- Cysts are typically found in formed stool, while trophozoites are typically found in diarrheal stool.
- Intestinal colonization occurs after ingestion of mature cysts in fecally contaminated food, water, or fomites.
- More often, the amoeba penetrates the submucosal layer and multiplies rapidly, causing lytic necrosis, abscess, and ulcer.
Entamoeba hartmanni
- Nonpathogenic amoeba with worldwide distribution.
- Life cycle similar to Entamoeba histolytica but lacks an invasive stage and does not ingest red blood cells.
Morphology of Entamoeba hartmanni
- Trophozoites:
- Measure 8 to 12μm, with a range of 5 to 15μm.
- Finger-shaped pseudopods exhibiting nonprogressive motility.
- Contain one nucleus with peripheral chromatin.
- Cysts:
- Range in size from 5 to 12μm, with an average size of 7 to 9μm.
- Spherical cysts may have one, two, three, or four nuclei.
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