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Parasitology > LAB- Laboratory Safety and Specimen Collection, Handling and Disposal > Flashcards

LAB- Laboratory Safety and Specimen Collection, Handling and Disposal Flashcards

1
Q

Precaution that treats everything inside the laboratory as infectious

A

Standard Precaution

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2
Q

Precaution that treats blood and other bodily fluids as infectious

A

Universal Precaution

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3
Q

Is key in the laboratory: practice preventive measures

A

Safety

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4
Q

Potential risks in the laboratory

A
  • Ingestion of eggs/ova
  • Skin penetration of infective larva
  • Infection of non-parasitic agents
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5
Q

Most commonly used preservative for stool

A

Formalin
(Fixed stool specimens for formalin may still be infectious)
(Ascaris contains three thick layers that allows for the specimen to live even after being preserved in formalin)

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6
Q

Why is timing a major factor for blood specimens?

A

As more time goes by, some parasites may be killed through lysis

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7
Q

What are some examples of blood parasites?

A

Malaria and babesiosis
(Malaria can be seen inside your blood and is usually transmitted inside the blood)
(Babesiosis are transmitted through White tailed deer ticks)

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8
Q

When Malaria and babesiosis are suspected, blood smears should be examined without delay. What type of smear is needed?

A

Both thick and thin smears

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9
Q

What type of blood is used for blood specimens?

A

Venous blood or capillary blood specimens

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10
Q

Parasitic nematodes in the family Onchocercidae that grows and develops inside mosquitos that exhibits periodicity

A

Microfilariae (seen in blood)

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11
Q

Fecal specimen is best collected in?

A

Sterile cup
(clean, wide-mouthed containers made of waxed cardboard or plastic with a tight-fitting lid to ensure retention of moisture and to
prevent accidental spillage)

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12
Q

Why does the sterile cup used for fecal specimen need to be tightly sealed?

A

Because fecal samples could come in different consistency (e.g. diarrhea, constipation). Also ensures that Fecal samples won’t be dried out as trophozoites might be disintegrated

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13
Q

Fecal specimens should contain the following 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
    (7-9 is filled out in the requisition form)
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14
Q

Protocols in stool collection for oocyte and parasites

A

Must have 3 specimens collected with no more than 7 days (e.g. collect every other day)

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15
Q

Protocol in stool collection for intestinal amoeba

A

Must have 6 specimens with no more than 10 days

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16
Q

Important factors to consider for intake of drugs

A
  • Antacids
  • Anti-diarrheals
  • Barium
  • Bismuth
  • Laxatives
    (These drugs decrease the amount of parasites found in the stool, same with antibiotics which decreases protozoans for several weeks)
    (wait 3-4 weeks after treatment for protozoans to collect for fecalysis)
    (Wait 5-6 weeks after treatment of helminths)
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17
Q

Amount of stool to be collected:

A
  • Dictated by the techniques that will be used
  • For stool examinations
    - Thumb sized for formed
    - 5-6 tablespoons for watery
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18
Q

What is most likely to be seen in a watery stool

A

Trophozoites (stable for about 30 minutes) (Is labile so easily deteriorates)

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19
Q

What is most likely to be seen in semi-formed stool

A

Both cysts and trophozoites (stable for about 1 hour)

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20
Q

What is most likely to be seen in formed stool

A

Cysts (stable for about 24 hours)

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21
Q

Should specimens contaminated with toilet water, urine, or soil be accepted for fecalysis? Why or why not?

A

▪ can destroy protozoan trophozoites
▪ may contain free-living organisms that would complicate
diagnosis of infections

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22
Q

Why is age of stool important for diarrheic specimens?

A

As trophozoites are seen in diarrheic specimens, they tend to die within 30 to 60 minutes

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23
Q

What should be done when there is an expected delay in examination?

A

Should be required to add preservatives (Note that trophozoites does not like preservatives, you can preserve them but they lose motility)

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24
Q

Golden standard for stool examination

A

Direct stool examination- Fresh sample
Concentration samples- Preserved sample
Permanent smear- Preserved sample

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25
Q

Preservation of specimens. Pros of fresh stool

A
  • Stool fixatives are not required
  • Possible observation of trophozoite motility
  • Low cost
  • Can be used for direct wet exam, concentration methods, permanent staining, immunoassays, special staining, etc.
  • Presents good morphology of the organism
26
Q

Preservation of specimens. Cons of fresh stool

A
  • May have excessive lag time between stool fixation or processing
  • Trophozoites may disintegrate, yielding to a false-negative result
27
Q

Preservation of specimens. Pros of preserved stool

A
  • Organism morphology is preserved when lag time between stool passage and fixation is short
  • Delivery time is not critical
  • Can be used for concentration methods, permanent staining, immunoassays, special staining etc.
28
Q

Preservation of specimens. Cons of Preserved stool

A
  • Expensive
  • Disposal of specimens in mercuric chloride
29
Q

Temporary storage of fecal samples should be kept at what temperature?

A

Refrigerated within 3-5 degrees Celsius (Prolonged refrigeration can bring about desiccation)

30
Q

Cons of Refrigerating stool samples

A

Kills trophozoites and could freeze stool samples, wag ifreeze. (Never keep them in incubators

31
Q

Does refrigeration damage helminth eggs and protozoans?

A

No

32
Q

All purpose fixative for the recovery of protozoans and helminth eggs and larvae

A

Formalin

33
Q

Concentration recommended for protozoan cysts

A

5% concentration of formalin

34
Q

Concentration recommended for helminth eggs

A

10% concentration of formalin

35
Q

Stool : Fixative Ratio

A

1:3
(Should be fixed within 30 minutes)

36
Q

Pros of using formalin

A
  • Overall useful for stool concentration
  • Easy to prepare, long shelf life
  • Formalinized stools can be used with some immunoassay kits
37
Q

Cons of using formalin

A
  • Does not preserve trophozoite
  • Does not adequately preserve the morphology of the organism
  • Morphologic details may fade through time
  • Pose a potential health hazard for lab scientist/handlers
38
Q

What buffer is used on formalin to preserve the morphological characteristics of the organism

A

Sodium phosphate

39
Q

Solution used for concentrating preserved stool using?

A

Formalin ether/Ethyl Acetate Concentration Technique (FECT)

40
Q

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

A

Schaudinn’s solution (5 stars for permanent staining)

41
Q

Fixative that contains mercuric chloride

A

Schaudinn’s solution
(Mercuric chloride is very toxic to humans)

42
Q

Fixative that uses plastic resin which serves to adhere a stool sample onto a slide

A

Polyvinyl alcohol (PVA)

43
Q

How long before you need to refix with formalin?

A

10 years

44
Q

Normally incorporated into the Schaudinns solution

A

PVA (Fixation is done by Schaudinns)

45
Q

Main advantage of PVA

A

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

46
Q

Drawback of PVA

A

Use of mercuric chloride

47
Q

Advantages of PVA

A
  • Good preservation of morphology of protozoan trophozoites and cysts
  • Used widely for permanent stained smears
    Long shelf-life at room temp
48
Q

Disadvantages of PVA

A

Environmental and health hazard as the solution contains mercuric chloride

49
Q

Preparation of Schaudinns fixative

A

600 ml of Mercuric Chloride (saturated aqueous solution) and 300 ml of 95% ethyl alcohol

50
Q

Advantages of Schaudinns

A
  • Good preservation of morphology of protozoan and cysts
  • Easy preparation of permanent stained smears
51
Q

Disadvantages of Schaudinns

A
  • Less suitable for concentration procedures
  • Contains mercuric chloride
  • Inadequate preservation of morphology of helminth eggs and larvae, coccidia, and microsporidia
  • Poor adhesion of liquid or mucoid specimens to slides (Hence why PVA is used)
52
Q

Contains merthiolate and iodine which acts as staining preservative

A

Merthiolate-Iodine-Formalin (MIF)
(Iodine is used for staining, while Formalin is used as the preservative)

53
Q

Additional info for MIF (Tinamad na ako mag input ng extra shit ni maam)

A
  • Preservative for wet mount smears
  • Useful for field surveys
  • For all common types of stools and aspirates
  • Protozoans, eggs and larva are identified without further staining of temporary wet mounts
54
Q

Advantages of MIF

A
  • Components both fix and stain organisms
  • Easy to prepare
  • Long shelf life
  • Useful for field survey
  • Suitable for concentration procedures
55
Q

Disadvantages of MIF

A
  • Not suitable for permanent smears stained with trophozoites
  • Inadequate preservation of morphology of protozoan trophozoites
  • Iodine interferes with other stains and fluorescence
  • Iodine may cause distortion of protozoa
56
Q

Fixative used for organisms are not as sharp as PVA or Schaudinn’s solution

A

Sodium acetate-acetic acid formalin (SAF) (acetic acid is used to lyse confusing stuff)
(Advantage of not containing Mercuric chloride)

57
Q

SAF preparation

A
  • 1.5 g of sodium acetate
  • 2.0 ml of Glacial acetic acid
  • 4.0 ml of Formaldehyde, 37– 40% solution
  • 92.0 ml of distilled water
58
Q

Advantages of SAF

A
  • Suitable for both concentration procedures and preparation of permanent stained smears
  • Easy to prepare and has long shelf-life
  • Suitable for acid fast, safranin staining methods
  • Compatible with fecal immunoassay kits
59
Q

Disadvantages of SAF

A

Requires adhesives

60
Q

Liquid fixative with a long shelf-life

A

SAF

61
Q

Where should you discard all used consumables?

A

Container with bleach solutions

62
Q

What should you do with unprocessed fresh samples

A

Either preserve or discard in a yellow waste container (should be tightly sealed inside the pilot container)

Parasitology (3 decks)

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