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Parasitology > Chapter 3 - Amebas > Flashcards

Chapter 3 - Amebas Flashcards

0
Q
  1. Excystation occurs where?
A

Ileocecal area of intestine.

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1
Q
  1. Phylum and subphylum of amoebae?
A

Phylum Sarcomastigophora

Subphylum Sarcodina

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2
Q
  1. Replication is accomplished by?
A

Multiplacation of nucleus via asexual binary fission.

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3
Q
  1. Conditions that trigger encystation?
A

Ameba overpopulation
pH change
Food supply
Available oxygen

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4
Q
  1. Standard microscopic procedures include examination of specimens for amebas using what methods?
A 
Saline wet preparations (motility)
Iodine wet preparations (structure)
Permanent stains (refractive and invisible structures)
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5
Q
  1. Amoebae with alternative diagnosis techniques?
A

Entamoeba histolytica
Naegleria fowleri
Acanthamoeba spp.

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6
Q
  1. Disease caused by amoeba?
A

Amebiasis.

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7
Q
  1. The only INTESTINAL amoeba considered to be a pathogen?
A

Entamoeba histolytica.

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8
Q
  1. Extraintestinal amebas cause symptoms involving areas such as?
A

Mouth, eye, and brain.

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9
Q
  1. Class of amebas?
A

Class Lobosea.

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10
Q
  1. Examples of intestinal amebas?
A

Entamoeba histolytica, E. hartmanni,
Entamoeba coli, E. polecki,
Endolimax nana, Iodamoeba bütschlii.

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11
Q
  1. Examples of extraintestinal amebas?
A

Entamoeba gingivalis
Naegleria fowleri
Acanthamoeba species.

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12
Q
  1. Entamoeba histolytica’s common associated diseases or condition names?
A

Intestinal amebiasis
Amebic colitis
Amebic dysentery
Extraintestinal amebiasis.

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13
Q
  1. What are chromatoid bars?
A

Structures (in the nucleus) that contain condensed RNA material.

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14
Q
  1. What is a diffuse glycogen mass?
A

A cytoplasmic area without defined borders that is believed to represent stored food. As the cyst matures, it disappears.

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15
Q
  1. As a result of nuclear division, a single cyst of E. histolytica produces how many motile trophozoites?
A

Eight.

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16
Q
  1. Vectors of E. histolytica?
A

Flies and cockroaches.

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17
Q
  1. How many percent of world population is infected by E. histolytica?
A

10%

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18
Q
  1. Cold countries with E. histolytica?
A

Alaska, Russia, and Canada.

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19
Q
  1. The range of symptoms varies and depends on what factors?
A

Location of parasite in the host

Extent of tissue invasion.

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20
Q
  1. Factors responsible for asymptomatic carrier state?
A

Parasite is low-virulence strain,
Inoculation into the host is low,
Patient’s immune system is intact.

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21
Q
  1. Medications for asymptomatic E. histolytica-infected individuals?
A

Paromomycin,
Diloxanide furoate (Furamide),
Metronidazole (Flagyl).

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22
Q
  1. Medications for symptomatic intestinal amebiasis?
A 
Iodoquinol,
Paromomycin,
Diloxanide furoate (Furamide).
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23
Q
  1. Medications for extraintestinal amebiasis?
A

Metronidazole (Flagyl) or tinidazole.

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24
Q
  1. Uncontaminated water is accomplished by?
A

Boiling, treating with iodine crystals,

Filtration and chemical treatment.

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25
Q
  1. Who studied the stool of a patient suffering from dysentery?
A

Loesch (late 1880’s)

*stool-dog-further study

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26
Q
  1. A nonpathogenic ameba that is morphologically identical to E. histolytica?
A

Entamoeba dispar.

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27
Q
  1. Average size (and size range) of E. histolytica trophozoites and cysts?
A

T: 12-25 um (8-65 um).
C: 12-18 um (8-22 um).

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28
Q
  1. Average size (and size range) of Entamoeba hartmanni trophozoites and cysts?
A

T: 8-12 um (5-15 um).
C: 7-9 um (5-12 um).

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29
Q
  1. Cytoplasmic inclusions of E. histolytica trophozoites?
A

Ingested RBC’s.

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30
Q
  1. Cytoplasmic inclusions of E. hartmanni trophozoites?
A

Ingested bacteria.

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31
Q
  1. The geographic distribution of E. hartmanni is?
A

Cosmopolitan.

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32
Q
  1. E. hartmanni was at one time designated as?
A

“Small race” E. histolytica, because of the many similarities between the two organisms.

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33
Q
  1. What is a karyosome?
A

A small mass of chromatin inside a nucleus.

“karyosomal chromatin”

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34
Q
  1. Average size (and size range) of Entamoeba coli trophozites and cysts?
A

T: 18-27 um (12-55 um).
C: 12-25 um (8-35 um).

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35
Q
  1. Cytoplasmic inclusions of E. coli trophozoites?
A

Vacuoles containing bacteria.

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36
Q
  1. The morphologic differentiation of E. coli and E. histolytica, as well as their pathogenicity, was not established until when?
A

The early 1900s.

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37
Q
  1. Average size (and size range) of Entamoeba polecki trophozoites and cysts?
A

T: 12-20 um (8-25 um).
C: 12-18 um (10-20 um).

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38
Q
  1. Cytoplasm (and inclusions) of Entamoeba polecki?
A

Granular and vacuolated

Ingested bacteria and food particles

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39
Q
  1. Peculiarities of E. polecki cysts?
A

One nucleus,
Inclusion mass,
Spherical to oval.

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40
Q
  1. What is an inclusion mass?
A 
A nondescript oval or round mass,
Seen in 50% of E. polecki cysts,
Non-glycogen-containing,
Elusive and doesn't have defined borders,
Makeup is unknown.
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41
Q
  1. E. polecki is considered what?
A

A parasite of pigs and monkeys.

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42
Q
  1. Highest prevalence of E. polecki occurs where?

Where else?

A

Papua, New Guinea.

Southeast Asia, France, USA

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43
Q
  1. Note on E. polecki?
A

All reported cases of E. polecki in USA in 1985 occured in SEA refugees who settled in Rochester, Minnesota.

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44
Q
  1. Symptom of patients with E. polecki?

And treatment?

A

Diarrhea.
(Metronidazole [Flagyl] and
diloxanide furoate [Furamide]).

45
Q
  1. Average size (and size range) of Endolimax nana trophozoites and cysts?
A

T: 7-10 um (5-12 um).
C: 7-10 um (4-12 um).

46
Q
  1. Peculiarities of Endolimax nana?
A

Large and blotlike karyosomes,
Absence of peripheral chromatin,
Spherical, ovoid, or ellipsoid cysts.

47
Q
  1. Endolimax nana are primarily found where?
A

Warm, moist regions of the world.

48
Q
  1. Average size (and size range) of Iodamoeba bütschlii trophozoites and cysts?
A

T: 12-18 um (8-22 um).
C: 8-12 um (5-22 um).

49
Q
  1. Peculiarities of Iodamoeba bütschlii?
A

One nucleus, large, central karyosome surrounded by refractive achromatic granules;
No chromatoid bars;
Ovoid, ellipsoid, triangular cyst;

50
Q
  1. Methods for lab diagnosis of Iodameoba bütschlii?
A

Iodine wet preps (Glycogen mass),

Trichrome staining.

51
Q
  1. Iodamoeba bütschlii is found where?
A

Worldwide and has a higher prevalence in tropical regions than in temperate regions.

52
Q
  1. Notes on Iodamoeba bütschlii?
A

Its nucleus resembles a basket of flowers;

Contaminated hog feces have been implicated as source of infection with I. bütschlii.

53
Q
  1. (Size range) of Entamoeba gingivalis trophozoites?
A

(8-20 um).

54
Q
  1. Cytoplasmic inclusions of E. gingivalis?
A

Digested WBCs and epithelial cells,
Bacteria,
Ingested RBCs.

55
Q
  1. Peculiarities of E. gingivalis?
A

Only ameba that ingests WBCs,

There’s no known cyst stage.

56
Q
  1. Specimens for E. gingivalis?
A

Mouth scrapings (gingival area);
Tonsillar crypts, pulmonary abscess, sputum;
Vaginal and cervical material.

57
Q
  1. E. gingivalis lives where?
A

Around the gum line of the teeth in the tartar and gingival pockets of unhealthy mouths;
Tonsillar crypts and bronchial mucus;
Vaginal and cervical specimens.

58
Q
  1. E. gingivalis acts as a what?
A

Scavenger, which feeds on disintegrated cells.

59
Q
  1. Infections of E. gingivalis are contracted via?
A

Mouth-to-mouth (kissing),

Droplet (contaminated drinking utensils).

60
Q
  1. E. gingivalis are frequently recovered where?
A

In patients suffering from pyorrhea alveolaris. It appears that the trophozoites thrive under disease conditions but do not produce symptoms of their own.

61
Q
  1. Note on E. gingivalis?
A

Discovered in 1849, it was the first ameba recovered from a human specimen.

62
Q
  1. The only amoeba with three morphologic forms?
A

Naegleria fowleri.

63
Q
  1. Naegleria fowleri’s three morphologic forms?
A

Ameboid trophozoite,
Flagellate form,
Cyst.

64
Q
  1. Size range (and shape) of Naegleria fowleri ameboid trophozoites, flagellate forms, and cysts?
A

AT: 8-22 um (elongate: broad anterior, tapered posterior),
F: 7-15 um (pear-shaped)
C: 9-12 um (round)

65
Q
  1. Peculiarities of N. fowleri?
A

One nucleus, large central karyosome minus peripheral chromatin,
2 flagella, thick cell wall.

66
Q
  1. Specimens for N. fowleri?
A

CSF, tissues, and

nasal discharge.

67
Q
  1. Methods in EXAMINING N. fowleri?
A

Saline and iodine wet preparations,
Culturing (ameboid trophozoites show a characteristic trailing effect when placed on agar plates that have been previously inoculated with gram-negative bacilli.)

68
Q
  1. Naegleria fowleri trophozoites are contracted by?
A

Swimming in contaminated water and inhaling contaminated dust.
They enter the nasal mucosa and often migrate to the brain.

69
Q
  1. N. fowleri is primarily found where?
A 
Warm bodies of water (lakes, streams, ponds, swimming pools),
Contaminated dust (Nigeria: warm climate).
70
Q
  1. Disease caused by N. fowleri?
A

Primary amebic meningoencephalitis (PAM).

-occurs when ameboid trophozoites of N. fowleri invades the brain, causing rapid tissue destruction.

71
Q
  1. Symptoms of PAM?
A

Fever, headache, sore throat, nausea, vomiting;
Symptoms of meningitis: stiff neck, seizures;
Smell and taste alterations, blocked nose, Kernig’s sign.

72
Q
  1. What is Kernig’s sign?
A

Diagnostic sign for meningitis, where the patient is unable to fully straighten his or her leg when the hip is flexed at 90 degrees because of hamstring stiffness.

73
Q
  1. What happens to the PAM patient if left untreated?
A

Death usually occurs 3 to 6 days after onset.

74
Q
  1. Medications for PAM?
A

Amphotericin B,
Rifampin or miconazole,
Rifampicin.

75
Q
  1. Mechanism of amphotericin B and miconazole?
A

Damage the cell wall of Naegleria, inhibiting the biosynthesis of ergosterol and resulting in increased membrane permeability, which causes nutrients to leak out of the cells.

76
Q
  1. Mechanism of rifampicin?
A

Inhibits RNA synthesis in the Naegleria by binding to beta subunits of DNA-dependent RNA polymerase, which in turn blocks RNA transcription.

77
Q
  1. The first cases of PAM were reported by whom?
A

Carter and Fowleri: Australia, 1965;

Butt and Patras: USA, 1966.

78
Q
  1. One noteworthy species that would possibly infect humans in the future?
A

Naegleria australiensis.

  • exists in Asia, Australia, Europe, USA.
  • pathogenic in mice (by intranasal instillation.)
79
Q
  1. Lab techniques aimed at CLASSIFYING, IDENTIFYING, and SPECIATING Naegleria?
A

PCR assay, monoclonal antibody testing,
Flow cytometry, DNA hybridization;
DNA restriction fragment length polymorphism (RFLP).

80
Q
  1. Average size (and size range) of Acanthamoeba trophozoites and cysts?
A

T: 25 um (12-45 um),
C: —–(8-25 um).

81
Q
  1. Peculiarities of Acanthamoeba species?
A

One nucleus,
Large karyosome & no obvious peripheral chromatin,
T: spinelike pseudopods - “acanthopodia”,
C: double cell wall - inner smooth, outer jagged cell wall.

82
Q
  1. Specimens of choice for Acanthamoeba spp.?
A

CSF, brain tissue, and corneal scrapings.

83
Q
  1. Suspected corneal scrapings (for Acanthamoeba spp.) may be cultured on what?
A

Non-nutrient agar plates seeded with gram-negative bacteria (specifically, a viable strain of Escherichia coli).

84
Q
  1. What are tracks?
A

These are set of marks produced on the agar (as Acanthamoeba organisms feed on Escherichia coli).

85
Q
  1. Technique of choice for SPECIATING Acanthamoeba? (For STAINING?)
A

Indirect immunofluorescent antibody staining.

Calcofluor white - Acanthamoeba cysts - fungi

86
Q
  1. First route of Acanthamoeba spp. into the human body?
A

Aspiration or nasal inhalation: T&C enter via lower respiratory tract or through ulcers in the mucosa or skin, migrate via hematogenous spread (ie, transported through the bloodstream) and invade the CNS. Victims are immunocompromised or debilitated.

87
Q
  1. Second route of Acanthamoeba spp. into the human body?
A

Direct invasion of the eye:
Contact lens wearers (soft c.l., contaminated homemade nonsterile saline solutions);
Those who have experienced trauma to the cornea.

88
Q
  1. Acanthamoeba species responsible for most CNS and eye infections in humans?
A

Acanthamoeba castellanii.

89
Q
  1. Acanthamoeba spp. associated with only CNS infection?
A

A. astronyxis,
A. divionensis,
A. griffini,
A. healyi.

90
Q
  1. Acanthamoeba spp. associated with only eye infection?
A

A. hatchetti,
A. lugdunensis,
A. polyphaga.

91
Q
  1. Acanthamoeba spp. associated with both CNS and eye infections?
A

A. castellani,
A. culbertsoni,
A. rhysodes.

92
Q
  1. Animals known to contract Acanthamoeba infections?
A

Rabbits, beavers, cattle,

Water buffalo, dogs, and turkeys.

93
Q
  1. Diseases caused by Acanthamoeba spp.?
A

Granulomatous amebic encephalitis (GAE) - CNS;

Acanthamoeba keratitis - cornea of the eye.

94
Q
  1. Symptoms of Granulomatous amebic encephalitis (GAE)?
A

Headaches, seizures, stiff neck, nausea, vomiting;
Granulomatous lesions of the brain.
*symptoms develop slowly.

95
Q
  1. Other body organs that Acanthamoeba spp. invade?
A

Kidneys, pancreas, prostate, and uterus.

*granulomatous lesions form.

96
Q
  1. Symptoms of Acanthamoeba keratitis?
A

Severe ocular pain and vision problems;

Perforation of the cornea and subsequent loss of vision.

97
Q
  1. Medications for GAE and Acanthamoeba keratitis?
A

GAE: sulfamethazine.
AK: itraconazole, ketoconazole, miconazole,
Propamidine isethianate (best), and rifampin.

98
Q
  1. Acanthamoeba shares many characteristics with?
A

The gram-negative bacteria Pseudomonas aeruginosa, which frequently occurs in standing water as an eye pathogen. It is believed that P. aeruginosa inhibits the activity of Acanthamoeba spp.

99
Q
  1. Testing methods aimed at DIFFERENTIATING Acanthamoeba spp.? (For TAXONOMIC CLASIFICATION?)
A 
Monoclonal antibodies and
flow cytometry (differentiating);
DNA RFLP (taxonomic classification).
100
Q
  1. Medium that supports E. histolytica in culture?
A

TYI-S-33.

101
Q
  1. Immunologically based procedures for E. histolytica?
A 
Antigen tests,
Enzyme-linked immunosorbent assay (ELISA),
Indirect hemagglutination (IHA),
Gel diffusion precipitin (GDP),
Indirect immunofluorescence (IIF).
102
Q
  1. Symptoms of amebic colitis?
A

Diarrhea, abdominal pain and cramping,
Chronic weight loss, anorexia,
Chronic fatigue, and flatulence.

103
Q
  1. Motility of E. hartmanni?
A

Nonprogressive,

finger-like pseudopods.

104
Q
  1. Motility of E. polecki?
A

Sluggish, nonprogressive (normal cons.),

Unidirectional, progressive (diarrheal).

105
Q
  1. Motility of Endolimax nana?
A

Sluggish, nonprogressive.

Blunt, hyaline pseudopods.

106
Q
  1. Motility of Iodamoeba bütschlii?
A

Sluggish, progressive.

107
Q
  1. Cytoplasm of I. bütschlii?
A

Coarsely granular and vacuolated.

108
Q
  1. Motility of E. gingivalis?
A

Active, varying pseudopod appearance.

109
Q
  1. Motility of Naegleria fowleri?
A

Sluglike, blunt pseudopods.

Jerky movements or spinning flagella.

110
Q
  1. Motility of Acanthamoeba spp.?
A

Sluggish, spinelike psudopods.

Parasitology (8 decks)

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