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paras Lecture > Intestinal and Commensal Amoebae > Flashcards

Intestinal and Commensal Amoebae Flashcards

1
Q

What is the main pathogenic amoeba responsible for intestinal infections?

A

Entamoeba histolytica.

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2
Q

How is Entamoeba histolytica transmitted?

A

transmitted through the ingestion of cysts via contaminated food or water.

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3
Q

What are the two forms of Entamoeba histolytica in its life cycle?

A

The trophozoite (active feeding form) and cyst (dormant, infectious form).

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4
Q

Which amoeba is often mistaken for Entamoeba histolytica but is non-pathogenic?

A

Entamoeba dispar.

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5
Q

What is the primary symptom of an infection with Entamoeba histolytica?

A

Dysentery, which includes severe diarrhea, often with blood and mucus

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6
Q

Which intestinal amoeba is considered non-pathogenic and commensal, often found in human intestines?

A

Entamoeba coli.

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7
Q

What is the method of diagnosing amoebic infections?

A

Microscopic examination of stool samples or serological tests in cases of extraintestinal amoebiasis.

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8
Q

What is the key difference in the appearance of cysts between Entamoeba histolytica and Entamoeba coli?

A

E. histolytica cysts typically have 1-4 nuclei, while E. coli cysts have up to 8 nuclei.

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9
Q

Which amoeba can cause liver abscesses in severe cases?

A

Entamoeba histolytica.

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10
Q

Which species of amoeba is typically non-pathogenic but can cause infections in immunocompromised individuals?

A

Entamoeba dispar.

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11
Q

How does Entamoeba histolytica cause damage in the host’s intestine?

A

trophozoites invade and destroy the intestinal mucosa, leading to ulcers and tissue destruction.

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12
Q

What are the two diagnostic techniques used to differentiate E. histolytica from E. dispar?

A

Serological tests and molecular diagnostic techniques like PCR.

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13
Q

What is the reservoir of infection for Entamoeba histolytica?

A

Humans are the primary reservoir of infection.

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14
Q

What drug is commonly used to treat infections caused by Entamoeba histolytica?

A

Metronidazole

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15
Q

How does the transmission of Entamoeba histolytica differ from that of commensal amoebae?

A

Both are transmitted through ingestion of cysts in contaminated food or water, but E. histolytica has a higher risk of causing disease, while commensal amoebae generally do not cause symptoms.

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16
Q

Why are cysts vital for the survival and transmission of intestinal amoebas?

A

Cysts are resistant forms that can survive outside the host in harsh environmental conditions.

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17
Q

What are the clinical differences between amoebiasis caused by Entamoeba histolytica and infections by commensal amoebae?

A

E. histolytica causes amoebic dysentery, with symptoms like bloody diarrhea, while infections by commensal amoebae, such as Entamoeba dispar, are typically asymptomatic.

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18
Q

Why is it challenging to differentiate between Entamoeba histolytica and Entamoeba dispar?

A

They are morphologically identical, so molecular or antigen detection methods are required to distinguish between the pathogenic E. histolytica and the non-pathogenic E. dispar.

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19
Q

Why is proper sanitation needed in preventing amoebic infections?

A

Poor sanitation leads to fecal contamination of water and food, increasing the risk of cyst ingestion and spread of amoebic infections.

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20
Q

Why are cysts more likely to be found in formed stools while trophozoites are found in liquid stools?

A

Cysts are the infective form that is passed in formed stools, while trophozoites, which are active and fragile, are more commonly found in liquid stools due to diarrhea.

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21
Q

What diagnostic techniques can distinguish between amoebic dysentery and bacillary dysentery?

A

Stool microscopy, antigen detection, and PCR can help identify amoebic dysentery, while culture and identification of bacteria like Shigella are used for bacillary dysentery.

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22
Q

What is the role of cysteine proteases in the pathogenicity of Entamoeba histolytica?

A

Cysteine proteases degrade host tissues and aid in the invasion of the intestinal lining, contributing to tissue damage and symptoms.

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23
Q

Why is PCR considered a more reliable diagnostic tool for Entamoeba histolytica infections?

A

PCR can specifically detect E. histolytica DNA, differentiating it from non-pathogenic amoebae and offering high sensitivity and specificity.

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24
Q

How does the epidemiology of E. histolytica differ between developing and developed countries?

A

In developing countries, poor sanitation and water quality contribute to higher transmission rates, whereas in developed countries, cases are usually imported.

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25
Q

single-celled protozoa that move using pseudopodia (false feet) and can exist as free-living organisms or parasites.

A

Amoebae

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26
Q

Which form of Entamoeba histolytica is infectious?

A

cyst form

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27
Q

Which diagnostic method is commonly used to identify Entamoeba histolytica?

A

Microscopy of stool samples to detect cysts or trophozoites.

28
Q

What is the difference between Entamoeba histolytica and Entamoeba dispar?

A

Entamoeba histolytica is pathogenic, while Entamoeba dispar is non-pathogenic.

29
Q

What is a commensal amoeba?

A

commensal amoeba is an amoeba that lives in the host without causing harm.

30
Q

What is the main route of transmission for intestinal amoebae?

A

Fecal-oral transmission

31
Q

Can Entamoeba histolytica spread beyond the intestines?

A

Yes, it can spread to the liver, lungs, and other organs, causing extraintestinal infections.

32
Q

What is the most common extraintestinal complication of Entamoeba histolytica infection?

A

Amebic liver abscess.

33
Q

What is the role of cysts in the life cycle of amoebae?

A

Cysts are the dormant, resistant form that allows amoebae to survive outside the host and be transmitted.

34
Q

What is the function of trophozoites in the life cycle of amoebae?

A

Trophozoites are the active, feeding, and multiplying stage of amoebae that cause damage within the host.

35
Q

Which species of Entamoeba is commonly found in pigs and is considered non-pathogenic in humans?

A

Entamoeba polecki.

36
Q

What is the primary environmental condition that facilitates the transmission of amoebae?

A

Poor sanitation and contaminated water sources.

37
Q

How can amoebic infections be prevented?

A

By improving sanitation, ensuring clean drinking water, and practicing proper hygiene.

38
Q

Parasitic infections are either due to the unicellular or
multi-cellular

A

Protozoan

39
Q

locomotory apparatus of protozoan

A

cilia, flagella, and pseudopodia

40
Q

two layers of cytoplasm

A

ectoplasm and endoplasm

41
Q

Nuclear membrane enveloping a fine reticulum filled with
nuclear sap and chromatin

A

Nucleoplasm

42
Q

two types of nucleoplasm or nuclear membrane

A

vesicular and granular

43
Q

 Most invasive of the Entamoeba parasites
 Only member of the family to cause colitis and amebic liver
abscess (ALA)

A

Entamoeba histolytica

44
Q

Presence of nuclear-encoded mitochondrial genes such as

A

pyridine nucleotide transhydrogenase and HSP 60

45
Q

Inhibits protein glycosylation

A

Tunicamycin

46
Q

release of enzymes and destroying
target cells then ingesting them afterwards

A

Cytophagocytosis

47
Q

breaks down mucin layer and
extracellular matrix of mucosal cells before the attachment
of amoeba

A

Cysteine proteinases

48
Q

Used for receptor-mediated adherence of amoeba/ameba to
its target cell

A

Galactose inhibitable adherence lectin (Gal lectin)

49
Q

Amebic phagocytosis of
killed or viable target cells (cell engulfment)

A

apoptotic death

50
Q

Manifestation of Infection

A

-Asymptomatic
-Amebic colitis
-Ameboma
-Amebic liver abscess (ALA)
-Pleuropulmonary amebiasis
-Secondary amebic meningoencephalitis
-Renal Involvement
-Genital Involvement

51
Q

5 bacteria in Bacillary Dysentery

A

 Shigella
 Salmonella
 Campylobacter
 Yersinia
 Escherichia coli

52
Q

Body defense against E. histolytica

A

-Innate / Natural immunity
-Adaptive Immunity

53
Q

Diagnosis for E. Histolytica

A
  1. Microscopic Examination
  2. Direct fecal smear (DFS)
  3. Concentration Methods
  4. Stool Culture
  5. Polymerase Chain Reaction (PCR), ELISA, Isoenzyme analysis
  6. Ultrasound, MRI and CT scan (radiographic studies)
  7. Serological Tests
  8. Aspiration of Tissue
  9. Colonoscopy
54
Q

An invasive procedure to check the status of the sigmoid colon

A

Sigmoidoscopy

55
Q

treatment for invasive amebiasis

A

Metronidazole

56
Q

treatment for asymptomatic cyst passers; also given after the course of metronidazole for invasive amebiasis

A

Dilozanide furoate

57
Q

5-nitroimidazole derivatives
are also effective for invasive amebiasis

A

Tinidazole and secnidazole

58
Q

 Does not need to be treated
 Presence of these organisms in stool/feces may be indicative of
food/water contamination
 Can easily be prevented and controlled through:
 Proper human waste disposal
 Good personal hygiene

A

COMMENSAL AMOEBAE

59
Q

three genera of commensal amoebae that may
be differentiated through their morphological features

A

Entamoeba
Endolimax
Iodamoeba

60
Q

 Morphologically similar to E. histolytica  Differ in DNA and rRNA and isoenzyme pattern
 May only be distinguished via molecular differentiation (e.g. PCR)

A

Entamoeba dispar

61
Q

 First detected in sewage
 Morphologically indistinguishable from E. histolytica and E.
dispar but differs biochemically (isoenzymes) and genetically
(DNA and RNA)

A

Entamoeba moshkovskii

62
Q

Physiologically unique: osmotolerant, able to grow at room
temperature and survive at temperatures ranging from 0 to 41°C

A

Entamoeba moshkovskii

63
Q

 Relatively similar to E. histolytica but smaller and more sluggish
 Does not ingest RBC

A

Entamoeba hartmanni

64
Q

 Largest intestinal amoeba
 Considerably more common than other human amoebae
 Harmless inhabitant of the colon
 Can survive putrefaction (decomposition/decaying)

A

Entamoeba coli

65
Q

-Found in intestines of monkeys and pigs (zoonotic – transmitted
from animals)
-Rarely infects humans

A

Entamoeba polecki

66
Q

 First amoeba of humans to be described
 Only found in the mouth
 Only amoebae that is not intestinal (all other amoebae
discussed are intestinal amoebae)

A

Entamoeba gingivalis

67
Q

 Smallest intestine-dwelling amoebae infecting humans
 Live both in vertebrates and invertebrates
 Lives in the human large intestine near the cecum

A

Endolimax nana

paras Lecture (5 decks)

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