2 - DIAGNOSTIC PARASITOLOGY Flashcards

1
Q

specimens used in the clinical lab

A
  • stool
  • urine
  • blood
  • lymphatic fluids
  • sputum
  • csf
  • biopsy
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2
Q

Most common method of diagnosis in parasites (protozoans and metazoans)
Best collected in clean, wide-mouthed containers made of waxed cardboard or plastic with tight-fitting lid to ensure retention of moisture and prevent spillage

A

examination of fecal specimens

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3
Q

recommended time of examination for liquid and soft stools

A

within half hour

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4
Q

recommended time of examination for fully-formed stool

A

within 3-4 hours

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5
Q

liquid and soft stools contain what type of parasites

A

protozoan trophozoites

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6
Q

fully-formed stools may contain what type of parasite?

A

protozoan cysts

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7
Q

? may be found in both liquid and fully-formed stools

A

helminth eggs

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8
Q

parasite stages detected in examination of fecal specimens

A
  1. cyst
  2. trophozoites
  3. oocysts
  4. eggs
  5. larvae
  6. adult worm
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9
Q

examination of 3 specimens must be collected ?

A

every other day

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10
Q

substances that interfere with stool examinations

A
  1. urine contamination
  2. castor or mineral oil
  3. barium, bismuth, kaolin, milk of magnesia, antacids]
  4. antibiotics/antimalarials
  5. enemas
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11
Q

amount of formed stool collected

A

2-5 grams

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12
Q

amount of watery stool collected

A

5-6 tablespoons

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13
Q

examination techniques for fecal specimens

A
  1. wet mount technique
  2. concentration techniques
  3. permanently stained smears
  4. culture
  5. immunoassay (antigen detection) - Giardia spp, Cryptosporidium spp, Entamoeba histolytica
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14
Q

Stool preservatives

A
  1. formalin
  2. Schaudinn’s solution
  3. polyvinyl alcohol
  4. sodium acetate formalin
  5. modified PVA
  6. two-vial system
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15
Q

recommended ratio of fixative to stool

A

3:1 (3 parts fixative, 1 part stool)

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16
Q

all purpose fixative

A

formalin

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17
Q

concentrations of formalin

A

5% — for cysts and protozoans
10% — for metazoans

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18
Q

advantages of formalin

A
  • easy to prepare
  • preserves specimens for several years
  • long shelf life
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19
Q

disasvantages of formalin

A

not suitable for permanent stains

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20
Q
  • fixative for permanent staining
  • contains mercuric chloride
  • can cause disposal problems
A

Schaudinn’s solution

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21
Q
  • acts as an adhesive for the stool specimen when preparing slide for staining
  • combined with Schaudinn’s fixative
A

Polyvinyl Alcohol

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22
Q
  • useful for fixation of parasite
  • cannot be used in permanent staining because it will lead to unsatisfactory result
A

merthiolate-iodine-formalin

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23
Q
  • used for permanent stains, direct mounts, and concentration procedures
  • does not contain mercury
  • quality is not good
A

Sodium Acetate-Formalin

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24
Q

in modified PVA, mercuric chloride is replaced by ?

A

copper sulfate and zinc sulfate

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25
Q

components of MIF

A
  • merthiolate — staining component; AKA thimerosal
  • iodine — staining component
  • formalin — preservative
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26
Q
  • one portion of specimen is fixed in three parts of 5%-10% buffered formalin
  • one portion in three parts of polyvinyl alcohol fixative
A

Two-vial technique

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27
Q

macroscopic examination

A
  • color (brown, LB, DB)
  • consistency (formed, soft, loose, watery)
  • presence of mucus, blood, larval, adult worms, proglottids
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28
Q

Type 1

A
  • separate hard lumps
  • very constipated
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29
Q

Type 2

A
  • lumpy and sausage like
  • slightly constipated
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30
Q

Type 3

A
  • a sausage shape with cracks in the surface
  • normal
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31
Q

Type 4

A
  • like a smooth, soft sausage or snake
  • normal
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32
Q

Type 5

A
  • soft blobs with clear-cut edges
  • lacking fiber
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33
Q

Type 6

A
  • mushy consistency with ragged edges
  • inflammation
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34
Q

Type 7

A
  • liquid consistency with no solid pieces
  • inflammation and diarrhea
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35
Q

macroscopic findings

A
  • macroscopic parasites
  • blood-tinged mucus
  • bloody mucus
  • bright red blood
  • occult blood
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36
Q

macroscopic parasites

A

pinworms, tapeworm proglottids, helminths

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37
Q

blood-tinged mucus

A

trophic amoebae

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38
Q

bloody mucus

A

amoebic ulcerations in the large intestine

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39
Q

bright red blood

A

bleeding hemorrhoids

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40
Q

occult blood

A

other gastrointestinal disorders, intestinal bleeding

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41
Q

microscopic examination

A
  1. DFS
  2. concentration techniques
  3. permanent stain
    - wheatley’s trichrome stain
    - iron hematoxylin stain
    - modified acid fast stain
    - microsporidia stain
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42
Q
  • most easily performed parasitological test
  • most useful when fresh specimens, liquid stools, or duodenal aspirates are examined for motile trophozoites/helminth larvae
A

Direct Wet Mount / Direct Fecal Smear

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43
Q

DFS process

A

small amount of stool is mixed with a drop of 0.85% saline and Lugol’s iodine and covered with a coverslip

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44
Q

alternative for DFS

A
  • modified D’Antoni’s iodine solution and Gram’s iodine
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45
Q

saline smear findings

A

huge amount of eggs, trophozoites, and cysts

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46
Q

iodine smear findings

A

eggs, cysts
(no trophozoites since iodine kills them)

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47
Q

additional mounting medium for DFS

A

buffered methylene blue

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48
Q

more sensitive in detecting cysts, larvae, and eggs, to prevent false positives

A

concentration techniques

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49
Q

concentration techniques

A
  • sedimentation
  • flotation
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50
Q

the heavier parasites settle at the bottom as a result of gravity or centrifugation

A

sedimentation

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51
Q

lighter parasite cysts and eggs rise to the surface of a solution of high specific gravity

A

flotation

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52
Q

sedimentation procedures

A
  1. Formalin Ether Concentration Technique (FECT)
  2. Acid Ether Concentration Techniques (AECT)
  3. Mini Parasep SF Kit
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53
Q
  • reagents: 10% formalin, ether
  • recommended for protozoans, helminth larvae, and eggs
A

formalin ether concentration technique

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54
Q
  • reagent: 40 % hydrochloric acid, ether
  • recommended for helminth (Trichuris, Capillaria, and trematode) eggs only
A

Acid Ether Concentration Techniques (AECT)

55
Q
  • reagents: 10% formalin, Triton C
  • minimalist preparation
A

Mini Parasep SF Kit

56
Q

flotation techniques

A
  1. zinc sulfate (ZnSO4) flotation
  2. brine flotation
  3. sheather’s sugar flotation
57
Q
  • reagent: 33% ZnSO4
  • specific gravity: 1.18-1.20
  • most common flotation technique
A

Zinc Sulfate Flotation

58
Q

reagent: saturated table salt (NaCl)
disadvantage: not applicable for operculated eggs

A

brine flotation

59
Q

reagent: boiled sugar with phenol
most recommended method for coccidian oocyst

A

sheather’s sugar flotation

60
Q
  • provides a permanent record of a patient’s specimen
  • allows review by consultants should difficulties arise in identification
A

permanent stains

61
Q

widespread acceptance because of its simplicity, reliability, and cost-effectiveness

A

Wheatley’s Trichrome Stain

62
Q

appropriate specimens for WTS

A

fixed in Schaudinn’s fixative or PVA fixative

63
Q

? -preserved specimens may be stained with trichrome, but results are less satisfactory

A

SAF- or MIF-

64
Q
  • previously more difficult to perform than the trichrome stain
  • may stain clearer and sharper than trichrome
A

Iron Hematoxylin Stain

65
Q

modified iron hematoxylin stain that may prove useful by incorporating ?

A

carbol fuchsin

66
Q

Modified iron hematoxylin stain that may prove useful by incorporating carbol fuchsin, allowing concurrent staining of acid-fast organisms such as

A

Cryptosporidium, Cyclospora, and Cystoisospora

67
Q
  • Detects oocysts of Cryptosporidium, Cyclospora, and Cystoisospora
A

modified acid-fast stain

68
Q

acid fast-staining techniques

A
  • modified Kinyoun method
  • modified acid-fast dimethyl sulfoxide
  • auramine-O
69
Q

stain for microsporidia (specifics)

A
  • Enterocytozoon bieneusi
  • Encephalitozoon intestinalis
70
Q

Modified trichrome stain uses an increased (10-fold) concentration of ? with increased staining time

A

chromotrope 2R

71
Q

additional techniques for examination of enteric parasites

A
  1. Cellulose Tape Technique for Pinworms
  2. Kato Thick Smear
  3. Egg Counting Techniques
  4. Egg Hatching Method
  5. Nematode Culture and Recovery Techniques
72
Q

Test for Enterobius vermicularis

A

Cellulose Tape Technique for Pinworms

73
Q

In Cellulose Tape Technique, specimens should be collected:

A
  • late night
  • first thing in the morning before bathing or defecation
74
Q
  • Qualitative test for detecting helminth eggs
  • Simple technique for mass stool examinations
  • Good for detecting eggs with thick egg shells
A

Kato Thick Smear

75
Q

how much stool is needed for Kato Thick Smear?

A

50-60mg

76
Q

materials for Kato Thick Smear

A

cellophane, glycerine, malachite green solution

77
Q

kato thick smear material that acts as a coverslip

A

cellophane

78
Q

kato thick smear material that acts as a cleaning reagent

A

glycerine

79
Q

kato thick smear material that provides color and minimizes brightness

A

malachite green solution

80
Q

Egg Counting Techniques

A
  1. Kato Katz
  2. Stoll Egg Count
81
Q

Uses measured amount of stool (quantitative)

A

Kato Katz

82
Q

additional equipment for Kato Katz

A
  • wire mesh
  • template
83
Q

wire mesh is for?

A

filtering stool sample

84
Q

template is for?

A

standardizing measurements

85
Q
  • Reagent: 0.1N NaOH
  • Dilution of the sample in sodium hydroxide
  • To count 24-hour stool sample
A

Stoll Egg Count

86
Q
  • Analysis of schistosomiasis
  • Detects the presence of eggs in light infections and determines their viability
A

Egg Hatching Method

87
Q

Materials for Egg Hatching Method

A

Urine/stool + water + Erlenmeyer Flask

88
Q

Hatched ? are positively phototropic and move towards/near the light

A

miracidia

89
Q

Stool is incubated in a humid environment to encourage egg hatching

A

Nematode Culture and Recovery Techniques (Coproculture)

90
Q

Nematode Culture and Recovery Techniques (Coproculture)

A
  1. Harada Mori Filter Paper Strip Culture
  2. Charcoal Culture
  3. Baermann Funnel Technique
91
Q
  • Larvae migrate from the feces into a paper strip, where they may be readily detected
  • Detects Hookworms and Strongyloides spp
A

Harada-Mori Filter Paper Strip Culture

92
Q
  • Larvae migrate into a dampened gauze pad, which is then placed in water, allowing the larvae to settle out
  • Charcoal simulates soil to encourage eggs to hatch
A

Charcoal Culture

93
Q
  • Sensitive and reliable method for recovery of Strongyloides and other nematode larvae from stool
  • Fecal sample is placed on several layers of gauze on top of a wire screen that is suspended in a funeral
  • Bottom of the funnel is clamped off, and water is added to the level of gauze
  • Larvae actively migrate through the gauze and settle to the bottom of the funnel
A

Baermann Funnel Technique

94
Q

Objects that Might Resemble Enteric Parasites

A

White blood cells/macrophages/squamous and columnar epithelial cells
Yeast and starch granules
Pollen and fungal conidia
Plant fibers
Pieces of vegetables or vegetable skins

95
Q

White blood cells/macrophages/squamous and columnar epithelial cells

A

Amoeba

96
Q

Yeast and starch granules

A

Protozoan Cyst

97
Q

Pollen and fungal conidia

A

Helminth eggs

98
Q

Plant fibers

A

Nematode larvae

99
Q

Pieces of vegetables or vegetable skins

A

Adult worms or proglottids

100
Q
  • Hexagonal bipyramidal crystal
  • Localized in the granules and cytoplasm of eosinophil and basophil
  • Presence indicated parasitic infection
  • Encountered during observation of KOH preparation of sputum
A

Charcot-Leyden crystals

101
Q

Examination of Blood

A

Thick and Thin Blood Smear
Buffy Coat Smear
Blood Concentration Technique

102
Q
  • For species identification
  • Spread over the slide in a thin layer, yielding intact, non-overlapping cellular elements
A

Thin Smear

103
Q
  • Used for diagnosis
  • Concentrated in a small area that is many cell layers deep
A

Thick Smear

104
Q

Concentration Techniques

A

Buffy Coat Smears
Membrane Filtration
Knott’s Concentration

105
Q

Diagnosis of Leishmania, Trypanosomes, Microfilariae
These do not reside in RBC

A

Buffy Coat Smears

106
Q

Lysed blood + 5-um Membrane filter

A

Membrane Filtration

107
Q

Blood + 2% Formalin = Centrifuge
Sediment: check for Microfilariae

A

Knott’s Concentration

108
Q

Blood for examination may be obtained by ?

A

fingerstick, earlobe puncture, venipuncture

109
Q

? anticoagulant is preferred

A

EDTA

110
Q

Best blood stain

A

Giemsa

111
Q
  • Host cell and parasite chromatin stains vividly but the hemoglobin in erythrocytes is only a pale red
  • Only stain that allows visualization of the erythrocyte stippling that occurs with infection by certain malarial parasites
A

Giemsa stain

112
Q

Alternative stain

A

Wright stain

113
Q

Stains parasite less well than Giemsa
Stains erythrocytes, producing a busier background

A

Wright

114
Q

Fresh Giemsa stain must be made each day of use by diluting stock solution into

A

phosphate-buffered water

115
Q

Buffered water must be maintained at

A

pH 6.8-7.2

116
Q

Urine

A

Trichomonas vaginalis
Schistosoma haematobium

117
Q

CSF

A

Trypanosoma spp.
Naegleria fowleri
Angiostrongylus cantonensis
Taenia solium (cysticercus larvae)

118
Q

Duodenal material

A

Entero test (Enteric capsule test)
Giardia lamblia
Strongyloides stercoralis

119
Q

Sigmoidoscopy material

A

Entamoeba histolytica

120
Q

Vaginal and urethral discharges, prostatic secretions

A

Trichomonas vaginalis

121
Q

Sputum

A

Paragonimus westermani, Pneumocystis jirovecii

122
Q

Skin biopsy

A

Onchocerca spp., Mansonella spp.

123
Q

Muscle biopsy

A

Trichinella spp.

124
Q

Rectal biopsy

A

Schistosomes eggs

125
Q

Lymph Node biopsy

A

Adult filarial worms

126
Q

Tissue Culture biopsy

A

Leishmania spp., Trypanosoma spp.

127
Q

Skin Hypersensitivity Tests

A

Bachman Skin Test
Casoni Skin Test
Dr. Montenegro Intradermal Test

128
Q

Bachman Skin Test

A

Trichinella spiralis

129
Q

Casoni Skin Test

A

E. granulosus

130
Q

Dr. Montenegro Intradermal Test

A

Leishmania spp

131
Q
  • Tests that can detect current infection
  • Can be performed without microscopy skills
  • Rapid, allows batch processing
  • Disadvantage: False-positives, cross-reactions
A

Immunoassays (Antigen Detection)

132
Q

Histidine-rich Protein II (HRP-II)

A

Plasmodium falciparum

133
Q

Parasite Lactate Dehydrogenase (pLDH)

A

Plasmodium spp

134
Q

Trichomonas vaginalis antigen

A

Trichomonas vaginalis