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MicroBio - Parasitology > Protozoa > Flashcards

Protozoa Flashcards

1
Q

Cytoplasm contains

A

Ultramicrospcopic organelles

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2
Q

Protozoan nuclei:

A

Macronucelus

Micronuclues

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3
Q

Long hair-like structures; characteristic of mastigophorans

A

Flagella

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4
Q

Short hair-like structures; surrounds the organism, often in rows

A

Cilia

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5
Q

Common life stage:

A

Trophozoit

Cyst

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6
Q

Dormant stages, produced by many of the protozoans
Capable of protection: During adverse environmental conditions
Generally non-feeding
Non-motile
Size: Usually smaller than trophozoites of the same species

A

Cyst

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7
Q

Metabolic stage
Active, vegetative; feeding
Capable of movement: Motility dependent on organelles
Size: Varied, ultramicroscopic to 1.0 mm
Shape: Varied, mostly subspherical; dependent upon cytoplasmic structure and organelles

A

Trophozoite

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8
Q

Cyst wall: Secreted scleroproteins (keratin-like or elastin-like albuminoids)

Glycogen vacuoles: Food storage vacuoles

Chromatoidal bodies: Composed of RNA-protein complex; crystalline; resemble viral particles; 0.3 to 1.0μm helical bodies; aggregate in crystalline array and become visible; serve as storage for Ribosomes

A

Cyst

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9
Q

Disease characteristics
Intestinal amebiasis
Non-dysenteric colitis
Amebic dysentery

A

Entamoeba histolytica

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10
Q

Tissue lysing enzymes: Cytolysins; proteolytic secretions

Ulceration: Penetration of the mucosal crypts; extension into submucosa forming FLASK-SHAPED lesions

Amebomas (amebic granulomas): Granulation tissues; tumors

A

Entamoeba histolytica

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11
Q

Collect three specimens: One every other day
Avoid contact with water or urine
Liquid stools: Examine within 30 minutes
Perform direct examination in physiological saline and Lugol’s iodine
Perform concentration technique

A

Lab ID:

Feces

Entamoeba histolytica

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12
Q

Charcot-Leyden crystals: Formed from the breakdown of eosinophilic blood cells; indication of bleeding or inflammation of the intestinal mucosa

A

Microspcopic examination

Entamoeba histolytica

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13
Q

Trophozoite form
Cytoplasm: Clean
Appearance: Finely granular
Inclusions: Occasional RBCs (in case of dysentery); few bacteria or debris in vacuoles

A

Lab ID:

Entamoeba histolytica

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14
Q

Nucleus:
Centrally located endosome

‘bulls eye’

A

Entamoeba histolytica

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15
Q

Worldwide distribution, but mostly in tropical areas with poor sanitation

Acquired through ingesting the quadrinucleate cyst on contaminated food or water.

A

Entamoeba histolytica

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16
Q

Causes amoebic dysentery. 10% extraintestinal invasion to liver, lungs, brain.

A

Entamoeba histolytica

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17
Q

Causes flask shaped ulcers

A

Entamoeba histolytica

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18
Q

Trophozoites often contain ingested RBCs (diagnostic), but need molecular testing to be sure.

A

Entamoeba histolytica

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19
Q

Often confused with Entamoeba histolytica

“Nonpathogenic”

A

Entamoeba Coli

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20
Q

Nucleus: Vesicular, dispersed type
Number: One
Peripheral chromatin: Coarse granules; irregular size and distribution
Karyosome: Small (larger than Entamoeba histolytica); usually eccentric

A

Entameoba coli

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21
Q

Cytoplasm
Appearance: Vacuolated, coarsely granular
Inclusions: Yeast (may include spores of Sphaerita), molds, bacteria, etc.
Motility: Sluggish; non-directional with blunt, poorly defined, pseudopodia

A

Entamoeba coli

Trophozoite form

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22
Q

Mature cysts of ___ ___ characteristically have eight nuclei, rarely 16.

A

Entamoeba coli

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23
Q

Nonpathogenic commensal.

Worldwide distribution

An indicator of poor hygiene.

A

Entamoeba coli

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24
Q

Cysts will have 5 or more nuclei with ECCENTRIC ENDOSOME

A

Entamoeba coli

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25
Q

Disease: Giardiasis

A

Giardia Lamblia

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26
Q

Incidence: Higher in children and young adults

Symptoms:
Irritation to the intestinal mucosa
Recurrent diarrhea (dehydration)
A

Giardia lamblia

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27
Q

Malabsorption

Large numbers of parasites attached to the intestinal mucosa:

Block absorption
Inhibits fat absorption:

Mechanical and chemical interference
Excludes absorption of fat soluble vitamins: Primarily VITAMIN A

A

Giardia lamblia

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28
Q

Habitat: Small intestine
Reservoir hosts: Beavers, small mammals, herbivores
Infective form: Mature quadrinucleated cyst
Mode of infection: Ingestion (may come from springs, creeks, or swimming pools

A

Giardia lamblia

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29
Q

Lab ID:
Feces and duodenal contents

Serological techniques, EIA, ELISA for antigen
Flourescent for presence in feces

A

Giardia lamblia

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30
Q

Trophozoite form: “wry little face“
Size: 9 to 20μm
Shape: Pear-shaped
Dorsal surface: Convex
Ventral surface: Concave with sucking disc
Nucleus: Two (bi-symmetrical arrangement)

A

Giardia lamblia

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31
Q

Trophozoite form: “wry little face“
Cytoplasm
Flagella: 8
Anterior: 2 (crossing at the midline)
Ventral: 4 (2 just behind the ventral notch; 2 behind the median bodies)
Caudal: 2 (extending from the posterior end)

A

Giardia lamblia

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32
Q

Worldwide distribution, common in daycare centers and institutionalized populations.

A

Giardia lamblia

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33
Q

Causes blunting of small intestinal villi and malabsorption, often of fats.
Symptoms of persistent diarrhea, gas, greasy stools, can become chronic or carriers.

A

Giardia lamblia

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34
Q

Irregular patterns of cysts and trophs in stool samples, but are diagnostic. Molecular methods are available (PCR, antigen)

A

Giardia lamblia

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35
Q

Pathogenicity
In females: Vaginitis, pruritus, strawberry cervix
In males: Urethritis, prostatovesiculitis
Habitat: Genitourinary tract
Mode of infection: Sexual contact

A

Trichomonas vaginalis

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36
Q

Lab ID:

Specimen source: Vaginal and urethral discharges, prostatic exudates
Trophozoite
Size 8 to 30μm
Flagella: 4 anterior
Undulating membrane: 1/3 to 1/2 the length of the organism

A

Trichomonas vaginalis

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37
Q

Pathogenicity: Considered nonpathogenic but often recovered from diarrheic stools
Habitat: Colon
Mode of infection: Ingestion, direct contact/sexual contact (prominent in homosexual communities)

A

Pentatrichomonas hominis

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38
Q 
Laboratory identification
Specimen source: Feces
Trophozoite
Size: 8 to 20μm
Flagella: 5 anterior and 1 posterior
Undulating membrane: Full length
A

Pentatrichomonas hominis

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39
Q

Pathogenicity: Considered to be nonpathogenic in the mouth (reported thoracic abscesses and respiratory infections)
Habitat: Mouth
Mode of infection: Direct contact

A

Trichomonas tenax

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40
Q

Worldwide distribution, humans only

Acquired through sexual intercourse or passed to infants during birth

A

Trichomonas

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41
Q

T. vaginalis is pathogenic, the other two are easily confused commensals.

T. vaginalis causes itching, petechial hemorrhaging, discharge (strawberry cervix)

A

Trichomonas

42
Q

Often asymptomatic in men
Increased risk of HIV passing or infection
Diagnosis: No cyst, 4 anterior flagella with half body undulating membrane

A

Trichomonas

43
Q

Causes balantidiasis, balantidial dysentery

Diarrhea and secondary complications

A

Balantidium coli

44
Q

Note: Only pathogenic ciliate.

A

Balantidium coli

45
Q 
Life cycle: 
Habitat: Cecum
Reservoir hosts: Swine, hogs
Infective form: Cyst stage
Mode of infection: Ingestion
A

Balantidium coli

46
Q

Nucleus: Two
Macronucleus: Large, elongated (kidney-bean shape)
Micronucleus: Minute, spherical

A

Balantidium coli

47
Q

Trophozoite form
Cytoplasm
Cytopyge: Excretory opening at posterior end of cell
Contractile vacuoles: One or two; pulsating (osmoregulatory function)

A

Balantidium coli

48
Q

Cytoplasm
Transparent cyst wall
Remnants cilia and gullet

A

Balantidium coli

49
Q

Worldwide distribution, but endemic in Japan, South Africa, C & S America, New Guinea

Acquired by eating contaminated food and water with feces from humans or animals.

A

Balantidium coli

50
Q

Causes ulcer in large intestine similar to E. histolytica, but very rarely travels to other organs.

Diagnosis: ID ciliated trophozoite or cyst in stool sample.

A

Balantidium coli

51
Q

Pathogenicity
Causes Primary Amebic Meningoencephalitis (PAM)
Central nervous system involvement
Rapid progression with high mortality

A

Naegleria fowleri

52
Q

Lab ID:

Specimen source: Cerebral spinal fluid

NOTE: Finding the trophozoite in the spinal fluid is sufficient reason to initiate treatment

A

Naegleria fowleri

53
Q

Wide distribution, thermotolerant, found in hot springs, water above 37 degrees Celsius.

Free living amoeba, but can infect humans through the nasal cavity.

Causes primary amoebic encephalitis (PAM).

A

Naegleria fowleri

54
Q

Death can occur within 5 days, rapid diagnosis and treatment essential.

Diagnosis: Amoeba isolated from CSF

A

Naegleria fowleri

55
Q

Pathogenesis: Terramebiasis

A

Acanthamoeba species

56
Q

Meningoencephalitis: Subacute; chronic (prominent species are A. castellani and A. culbertsoni)

A

Acanthamoeba species

57
Q

Keratitis: Severe damage to eyes; blindness (prominent species are A. castellani and A. polyphaga),early on tied heavily to homemade contact lens solutions

A

Acanthamoeba species

58
Q

Habitat: Usually free living; skin, central nervous system and corneal regions of the eye
Reservoir hosts: A variety of mammals and invertebrates (oysters, grasshoppers and snails)
Infective form: Amebic trophozoites or cysts
Mode of infection: Uncertain

A

Acanthamoeba species

59
Q

Lab ID:

Specimen source: Exudates, tissue sections, CSF

A

Acanthamoeba species

60
Q

Identification of ______ species: Requires differentiation from N. fowleri

_______: No flagellated stage
Presence of trophozoites and cysts in tissue indicative of ______ species

A

Acanthamoeba species

61
Q

More ubiquitous environmentally, cysts survive desiccation well. Immune compromised individuals more at risk.

A

Acanthamoeba spp.

62
Q

Known to cause keratitis after entering eye through non-sterile contact lens solution.

A

Acanthamoeba spp.

63
Q

Causes a slow granulomatous amoebic encephalitis (GAE). Can enter through breaks in skin and respiratory tract.
Diagnosis: Amoeba isolated from eye or brain tissue.

A

Acanthamoeba spp.

64
Q

Leishmania has 3 types of disease:

A

a) visceral leishmaniasis
b) cutaneous leishmaniasis
c) mucocutaneous leishmaniasis

65
Q

Discovered by Ronald Ross in 1903 (Leishman and Donovan)

66
Q

Common names: Kala-azar, Dum-Dum fever

A

Leishmania donovani complex

67
Q

Darkening of the skin (Kala-azar, black poison)
Destruction of reticuloendothelial cells and histiocytes throughout the body
Hepatosplenomegaly
Frequently fatal (95% for untreated cases)
Immunity: Gamma globulins; only after recovery from initial infection

A

Visceral leishmaniasis

Leishmania donovani complex

68
Q

Common name: Oriental sore

A

Leishmania tropica

69
Q

Initial lesion: Shallow, dry scaly ulcerated lesion
Ulceration: Crater-like with thickened edges
Secondary bacterial infections common
Ulcers leave disfiguration
Seldom fatal
Immunity: Self-healing process confers immunity

A

Cutaneous leishmaniasis

Leishmania tropica

70
Q

Common name: “Baghdad boil”

A

Leishmania major

71
Q

Initial lesion: Shallow, dry scaly ulcerated lesion
Ulceration: Crater-like with thickened edges
Secondary bacterial infections common
Ulcers leave disfiguration
Seldom fatal
Immunity: Self-healing process confers immunity

A

Cutaneous leishmaniasis (like tropica)

Leishmania major

72
Q

Common names: Espundia, uta, chiclero ulcer

A

Leishmania braziliensis/L. panamensis

73
Q

Ulcers with moist centers
Secondary lesions: Destruction of the nasal septum; masses of necrotic tissue
Marked deformities
Frequently fatal

A

Mucocutaneous leishmaniasis

Leishmania braziliensis/L. panamensis

74
Q

Habitat: Phagocytic macrophages of the reticuloendothelial system
Intermediate host: Sandflies of the genus Phlebotomus
Reservoir hosts: Cats, dogs, other mammals
Infective stage: Promastigote
Mode of infection: Injection by the bite of the vector

A

Leishmania

75
Q 
Specimen source
Tissue impression smears and sections (stained by Wright-Giemsa)
Exudates or scraping of lesions
Buffy coat preparations of venous blood
Bone marrow aspirations
Culture on Novy, MacNeal and Nicolle (NNN) medium
Animal inoculation: Hamsters
Serological testing

b) Looking for amastigotes!!!

A

Leishmania

76
Q

Nearly worldwide distribution

Causes 3 different diseases based on species
Visceral, cutaneous, mucocutaneous

A

Leishmania spp

77
Q

Acquired through the bite of an infected sandfly. Promastigotes injected into the skin which become amastigotes once phagocytized.

A

Leishmania spp

78
Q

Symptoms: vary with species, but fever (twice daily), splenomegaly, skin nodules progressing to ulcers.
Diagnosis: Tissue samples from edge of ulcer, PCR and stain for amastigotes in blood or tissue

A

Leishmania spp

79
Q

Discovery:
Sleeping Sickness known in Europe since the 1700s. Discovered in 1895 by Bruce in African cattle: First recovered from humans in 1902.

A

Trypanosoma

80
Q

Trypanosomes were first observed in the blood of amphibians (frogs, etc.), but since then many other species have been discovered in the blood of many vertebrates, including fish, reptiles, birds and mammals. Much research and investigation has been conducted on this genus because of the great debilitation of infections in humans and domestic animals.

A

Trypanosoma

81
Q

Common name: African sleeping sickness

A

Trypanosoma brucei

82
Q

West African sleeping sickness

Affects humans more (reservoir host), spread by riverine TseTse fly

A

T. brucei gambiense

83
Q

East African sleeping sickness

Affects game animals more (reservoir host), savanna-woodland TseTse fly

A

T. brucei rhodesiense:

84
Q

Pathogenesis: Often fatal in untreated cases
Localized inflammatory reaction near entry site
Invasion of lymph nodes: Winterbottom’s sign (posterior cervical lymph nodes involved)

A

Trypanosoma brucei

85
Q

Invasion of central nervous system (CNS)
Disinclination to exertion and lack of interest
Reflexes retarded: Difficulty in articulation, incoherent speech, loss of coordination
Lapses of diurnal sleep
Coma: Usually terminal
Evades immune system by varying surface antigens (1000 VSGs)

A

Trypanosoma brucei

86
Q

Duration:

CHRONIC may last for several years

A

T. brucei gambiense

87
Q

Easily cured during circulatory invasion; fatal in 12 to 18 months, ACUTE

A

T. brucei rhodesiense

88
Q

Habitat: Circulatory system, central nervous system, lymph nodes, spleen and other organs
_____?: Domestic animals
_____?: Game animals

A

T. brucei gambiense: Domestic animals

T. brucei rhodesiense: Game animals

89
Q

Infective stage: Metacyclic trypomastigote

Mode of infection: Bite of tsetse flies

A

Trypanosoma brucei

90
Q

Specimen source: Blood or CSF, thick and thin blood smears

_____ from a lymph node, _____ in blood

A

gambiense from a lymph node,

rhodesiense in blood

91
Q

Common name: Chagas disease

A

Trypanosoma cruzi

92
Q

Pathogenesis: South American trypanosomiasis

A

Trypanosoma cruzi

93
Q

Localized severe inflammation: Chagoma; periorbital swelling, ROMANA’s SIGN
Invasion of host cells: Cardiomyopathy
Multiple cardiac symptoms
Congestive heart failure
Mega-disease: Enlargement of visceral organs; dilatation of digestive tract
Frequently fatal

A

Trypanosoma cruzi

94
Q

Habitat: Circulatory and reticuloendothelial systems; heart muscle; bone marrow, etc.

Intermediate hosts (vectors): Reduviid bugs (KISSING BUGS)

Reservoir hosts: Various mammals; wood rats, opossums, armadillos

A

Trypanosoma cruzi

95
Q

Infective stage: Metacyclic trypomastigote

Mode of infection: Contamination of infected bug feces in the bite wound; also transfusion and organ transplants

A

Trypanosoma cruzi

96
Q

Which of these organisms tend to infect liver tissue?

A. Giardia lamblia
B Leishmania major
C. Entamoeba histolytica
D. Paragonimus westermani

A

C. Entamoeba histolytica

97
Q

What would be the best treatment option for giardiasis?

A. Metronidazole
B. Artemisinin
C. Aspirin
D. Fluoroquinolone

A

A. Metronidazole

98
Q 
Which of these diseases has been termed the “Baghdad boil”?

A. Trypanosomiasis
B. Cryptosporidiosis
C.  Acanthamoeba infection
D.  Leishmaniasis
A

Leishmania major

99
Q

periorbital swelling (T. Cruzi)

A

ROMANA’s SIGN

100
Q

Mega-disease: Enlargement of visceral organs; dilatation of digestive tract

MicroBio - Parasitology (14 decks)

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