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Parasitology-Lab > U1 - Lab Safety and Specimen Handling to Disposal > Flashcards

U1 - Lab Safety and Specimen Handling to Disposal Flashcards

1
Q

Toxic substances are handled under?

A

a safety hood

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2
Q

parasites that will be thriving in the host

A

helminths

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3
Q

type of host during adult stage

A

definitive host

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4
Q

type of host during larval stage

A

intermediate host

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5
Q

type of host during the egg stage

A

parasite in diagnostic stage

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6
Q

types of helminth

A
  1. nematode
  2. trematode
  3. cestode
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7
Q

T/F:
When a specimen is “fixed”, it means that everything is already killed; hence, it is not infectious because it is already preserved.

A

True

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8
Q

best way to preserve the eggs and prevent development

A

warm/ heated 10% formalin

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9
Q

key in the laboratory

A

safety

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10
Q

difference between standard and universal precautions

A

standard: everything is infectious
universal: all samples are highly infectious

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11
Q

What should be practiced in the laboratory?

A

standard precautions

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12
Q

potential risks in the para lab

A
  1. ingestion of eggs/ ova
  2. skin penetration of infective larva
  3. infection of non-parasitic agents
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13
Q

T/F:
fixed stool specimens in formalin is no longer infectious

A

False;
may still be infectious

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14
Q

can still develop and are infectious even in preserved in formalin

A

Ascaris eggs

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15
Q

special factor in blood specimen collection

A

timing

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16
Q

T/F:
Blood should be collected before treatment is initiated.

A

True

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17
Q

Why is timing important?

A

to ensure that the parasite will not be missed

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18
Q

When these are suspected, blood smears should be examined without delay.

A

Malaria and Babesiosis

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19
Q

T/F:
Only one blood smear is needed.

A

False;
multiple blood smears might be needed

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20
Q

reason why multiple blood smears are needed

A

Parasitemia or the presence of parasites in the blood could actually fluctuate

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21
Q

exhibit periodicity and is seen in lymphatic fluids

A

Microfilariae

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22
Q

What type of blood samples are collected to detect parasitic infections?

A

venous and capillary

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23
Q

multiple specimens recommended for adequate yield of 1 parasite

A

fecal specimen

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24
Q

Criteria for fecal specimen container

A
  1. clean
  2. wide-mouthed
  3. made of waxed carboard or plastic
  4. has a tight-fitting lid
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25
Q

Why should the lid of the container be tight-fitting?

A

to ensure retention of moisture
to prevent accidental spillage

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26
Q

Fecal specimen should be submitted with these information

A
  1. patient’s name
  2. age
  3. sex
  4. date/time of collection
  5. requesting physician
  6. requested procedure
  7. presumptive diagnosis
  8. prior infections
  9. travel history
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27
Q

Specimen protocol:
___ specimens are collected every other day to consider the adequate or minimum necessary for the detection of ova and parasite with no more than ___ days

A

3
7

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28
Q

Specimen protocol:
___ specimens are collected every other day to consider the adequate or minimum necessary for the detection of intestinal amebiasis with no more than ___ days

A

> 6
10

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29
Q

information on the fecal specimen container

A
  1. patient’s name
  2. patient’s ID number
  3. date and time of collection
  4. requesting physician
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30
Q

3 types of stool consistency

A

watery
semi-formed
formed

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31
Q

amount of trophozoites from greatest to least in different types of stool consistency

A
  1. watery (greatest)
  2. semi-formed
  3. formed (least)
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32
Q

amount of cyst from greatest to least in different types of stool consistency

A
  1. formed (greatest)
  2. semi-formed
  3. watery (least)
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33
Q

time validity for examination of structures:
watery:
semi-formed:
formed:

A

watery: 30 minutes
semi-formed: 1 hour
formed: up to 24 hours

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34
Q

Stool is refrigerated at what temperature?

A

3-5 C

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35
Q

Important factors to consider

A
  1. intake of drugs/ medicinal substances
  2. intake of antibiotics
  3. amount of stool to be collected
  4. contamination with toilet water, urine or soil must be prevented
  5. age of stool sample is very important for diarrheic specimens
  6. delay in examination of specimens
  7. temporary storage of fecal samples
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36
Q

5 examples of drugs or medicinal substances

A
  1. antacids
  2. anti-diarrheals
  3. barium
  4. bismuth
  5. laxatives
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37
Q

deferral for intake of drugs or medicinal substances

A

1 week from last intake

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38
Q

effect of intake of drugs or medicinal substances

A

leaves crystallized residues

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39
Q

usually decreases the number of protozoans for several weeks

A

antibiotics

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40
Q

deferral for protozoan treatment/ anti-protozoan drugs

A

3-4 weeks after treatment

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41
Q

duration of deferral for anti-helminthic drugs

A

5-6 weeks after last intake

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42
Q

amount of fecal specimen for routine stool examination

A

formed: thumb-sized
watery: 5-6 tbsp.

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43
Q

effect of contamination with toilet water, urine, or soil

A
  1. can destroy protozoan trophozoites
  2. may contain free-living organisms that would complicate diagnosis of infections
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44
Q

Age of stool sample is very important for?

A

diarrheic specimens

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45
Q

Trophozoites are likely to die within _________ after passage

A

30 minutes to 1 hour

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46
Q

Why does stool require preservation?

A

to ensure that parasites are present in identifiable stage

47
Q

effect of prolonged refrigeration

A

desiccation (drying)

48
Q

effect of refrigeration

A

trophozoites: killed
helminth eggs: usually not damaged
protozoan cysts: usually not damaged

49
Q

prohibitions of fecal storage

A
  1. never freeze
  2. never incubate
  3. never put in clean ref
50
Q

Where should the fecal specimen be refrigerated?

A

dirty ref

51
Q

3 examinations (gold standard for stool examination)

A
  1. direct stool examination (preserved sample)
  2. concentration methods (preserved sample)
  3. permanent smear (preserved sample)
52
Q

T/F:
Motility of trophozoites can be observed in the preserved sample.

A

False

53
Q

type of sample preserved by trophozoites

A

fresh sample

54
Q

5 Stool Preservatives

A
  1. Formalin
  2. Schaudinn’s Solution
  3. Polyvinyl Alcohol (PVA)
  4. Merthiolate-Iodine Formalin (MIF)
  5. Sodium Acetate-Acetic Acid Formalin (SAF)
55
Q

an all-purpose fixative

A

formalin

56
Q

Formalin 5% and 10% concentration purposes

A

5% concentration: protozoan cysts
10% concentration: helminth eggs and larvae

57
Q

Formalin may be buffered with _________ ____________ to preserve the morphological characteristics of the organisms

A

sodium phosphate

58
Q

FECT stands for?

A

formalin-ether/ ethyl acetate concentration technique (FECT)

59
Q

used to preserve fresh stool in preparation for staining the stool smears

A

Schaudinn’s solution

60
Q

best preservative for the parasites

A

Schaudinn’s solution

61
Q

What chemical does Schaudinn’s solution contain?

A

mercuric chloride

62
Q

T/F:
Mercuric chloride is highly toxic to humans, and problems regarding its disposal may arise.

A

True

63
Q

Stool: Fixative Ratio

A

1:3

64
Q

Using formalin, stool must be fixed within how many minutes?

A

30 minutes

65
Q

preservative designed for fresh stool specimens or samples from the intestinal mucosal surface for permanent staining

A

Schaudinn’s solution

66
Q

a plastic resin which serves to adhere a stool sample onto a slide

A

polyvinyl alcohol (PVA)

67
Q

PVA is normally incorporated into?

A

Schaudinn’s solution

68
Q

T/F:
PVA is normally incorporated into Schaudinn’s solution, but actual fixation is done by the Schaudinn’s.

A

True

69
Q

main advantage of using PVA

A

related to the preservation of protozoan cysts and trophozoites for permanent staining

70
Q

stools preserved using this PVA can be concentrated using _____ and can be shipped to any laboratory for further examination.

A

FECT

71
Q

Drawback of PVA

A

use of mercuric chloride

72
Q

preservatives with mercuric chloride

A

Schaudinn’s solution
Polyvinyl alcohol (PVA)

73
Q

As PVA is combined with Schaudinn’s solution, what are the bases?

A

Zinc sulfate
Copper sulfate
Mercuric chloride

74
Q

In modified PVA copper or zinc, permanent smears can be made and stained with?

A

trichrome

75
Q

T/F:
In modified PVA, copper is preferred over zinc.

A

False;
zinc over copper

76
Q

T/F:
Modified PVA has mercuric chlorode.

A

False;
none

77
Q

contains merthiolate (also called thimerosal) and iodine which act as staining components

A

Merthiolate-Iodine-Formalin (MIF)

78
Q

merthiolate is also called?

A

thimerosal

79
Q

staining components of Merthiolate-Iodine-Formalin (MIF)

A

merthiolate/ thimerosal
iodine

80
Q

preservative component of MIF

A

formalin

81
Q

useful for the fixation of intestinal protozoans, helminth eggs, and larvae

A

Merthiolate-Iodine-Formalin (MIF)

82
Q

preservative that is useful for field surveys

A

Merthiolate-Iodine-Formalin (MIF)

83
Q

preservative for all common types of stools and aspirates

A

Merthiolate-Iodine-Formalin (MIF)

84
Q

can be a substitute for Schaudinn’s solution

A

MIF

85
Q

T/F:
Using MIF, protozoans, eggs, and larva are identified without further staining in temporary wet mounts

A

True

86
Q

preservative that has the advantage of not containing mercuric chloride

A

Sodium acetate-acetic acid formalin (SAF)

87
Q

T/F:
Images of organisms fixed in SAF - not as sharp after staining compared with those fixed in PVA or Schaudinn’s solution

A

True

88
Q

a liquid fixative with a long shelf-life

A

Sodium acetate-acetic acid formalin (SAF)

89
Q

preservative that is used in concentration techniques, permanent staining, and fecal immunoassays

A

Sodium acetate-acetic acid formalin (SAF)

90
Q

preservative where the sediment obtained is used for the preparation of permanent smears

A

Sodium acetate-acetic acid formalin (SAF)

91
Q

Pros and cons of fresh stool

A

Pros:
1. stool fixatives are not required
2. trophozoite motility observation
3. low cost
4. good morphology of the organism
5. can be used for direct wet exam, concentration methods, permanent staining, immunoassays, special staining, etc.

Cons
1. excessive lag time between stool fixation or processing
2. trophozoites may disintegrate, yielding to a false-negative result

92
Q

Pros and cons of preserved stool

A

Pros:
1. organism morphology is preserved when lag time between stool passage and fixation is short
2. delivery time is not critical
3. can be used for concentration methods, permanent staining, immunoassays, special staining, etc.

Cons:
1. expensive
2. disposal of specimens in mercuric chloride

93
Q

Pros and cons of formalin

A

Pros:
1. useful for stool conc.
2. easy to prepare
3. long shelf life
4. formalized stools can be used with some immunoassay kits

Cons:
1. does not preserve trophozoites well
2. does not adequately preserve the morphology of the organism
3. morphologic details may fade through time
4. pose a potential health hazard for lab scientist

94
Q

Pros and cons of Schaudinn’s solution

A

Pros:
1. good preservation of morphology of protozoan trophozoites and cysts
2. easy preparation of permanent stained smears

Cons:
1. less suitable for concentration procedures
2. contains mercuric chloride
3. inadequate preservation of morphology of helminth eggs and larvae, coccidia, and microsporidia
4. poor adhesion of liquid or mucoid specimens to slides

95
Q

In Schaudinn’s solutions, are trophozoites destroyed?

A

killed but not destroyed

96
Q

In Schaudinn’s solutions, is the trophozoite’s motility preserved?

A

motility: not preserved
morphology: preserved

97
Q

Pros and cons of PVA

A

Pros:
1. good preservation of morphology of protozoan trophozoites and cysts
2. used widely for permanent stained smears
3. long shelf life at room temperature

Cons:
1. environmental and health hazard (mercuric chloride)

98
Q

Pros and cons of MIF

A

Pros:
1. components both fix and stain organisms
2. easy to prepare
3. long shelf life
4. useful for field surveys
5. suitable for conc procedures

Cons:
1. not suitable for permanent smears stained with trichrome
2. inadequate preservation of morphology of protozoan trophozoites
3. iodine interferes with other stains and fluorescence
4. iodine may cause distortion of protozoa

99
Q

Pros and cons of SAF

A

Pros:
1. suitable for both conc procedures and preparation of permanent stained smears
2. easy to prepare
3. long shelf life
4. suitable for acid-fast, safranin staining methods
5. compatible with fecal immunoassay kits

Cons:
1. requires adhesives
2. permanent stains not as good as with PVA or Schaudinn’s fixative

100
Q

Fresh stool
direct wet mount:
conc procedure:
permanent staining:

A

direct wet mount: yes
conc procedure: yes
permanent staining: yes

101
Q

Formalin
direct wet mount:
conc procedure:
permanent staining:

A

direct wet mount: yes
conc procedure: yes
permanent staining: no

102
Q

Schaudinn’s solution
direct wet mount:
conc procedure:
permanent staining:

A

direct wet mount: no
conc procedure: no
permanent staining: yes

103
Q

PVA
direct wet mount:
conc procedure:
permanent staining:

A

direct wet mount: no
conc procedure: no
permanent staining: yes

104
Q

Modified PVA

A

direct wet mount: no
conc procedure: no
permanent staining: yes

105
Q

MIF
direct wet mount:
conc procedure:
permanent staining:

A

direct wet mount: yes
conc procedure: yes
permanent staining: no

106
Q

SAF
direct wet mount:
conc procedure:
permanent staining:

A

direct wet mount: yes
conc procedure: yes
permanent staining: yes

107
Q

After processing fresh stool sample, discard all consumables in a container with?

A

bleach solution

108
Q

bleach solution ratio

A

1:10 or 10% sodium hypochlorite solution

109
Q

What are the consumables that must be discarded in a container with bleach solution

A

applicator sticks
slides

110
Q

Remaining unprocessed fresh samples may be preserved or discarded in a?

A

yellow waste container

111
Q

T/F:
Stool must be tightly sealed inside the pilot container.

A

True

112
Q

T/F:
Lugol’s iodine component should always be freshly prepared since it is unstable.

A

True

113
Q

T/F:
Stool contaminated with toilet water must be rejected for analysis.

A

True

Parasitology-Lab (8 decks)

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