Laboratory Safety and Sample Collection

Question 1

“Treat all sample infectious”

Answer 1

Standard Precaution

Question 2

“All sample can induce bloodborne pathogens”

Answer 2

Universal Precaution

Question 3

Potential risks in parasitology laboratory

Answer 3

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

Question 4

True or false. Fixed stool using specimens are already free from pathogens.

Answer 4

False. They are still infectious.

Question 5

When should blood specimens be collected?

Answer 5

Before treatment is initiated

Question 6

Capacity of fecal sample container

Answer 6

0.5 pint or approx. 240 ml

Question 7

Labile stage and feeding form of protozoans

Answer 7

Trophozoites

Question 8

How many stools samples should be collected and how frequent?

Answer 8

3 specimens collected within 6-7 days (no more than 7 days)

Question 9

How many stools samples should be collected for intestinal amebiasis and how frequent?

Answer 9

No more than 6 specimens collected within 10 days

Question 10

How many weeks of deferment if the patient is taking antiprotozoan?

Answer 10

3-4 weeks

Question 11

How many weeks of deferment if the patient is taking helminthic drugs?

Answer 11

5-6 weeks

Question 12

Drugs that require 1 week deferment

Answer 12

o Antacids
o Anti-diarrheal
o Barium
o Bismuth
o Laxatives

Question 13

Why does the intake of antibiotic affect the result of stool analysis?

Answer 13

They decrease the number of protozoan for several weeks

Question 14

Amount of stool to be collected

Answer 14

Thumb-sized (solid)
5-6 tablespoons (watery)

Question 15

Trophozoites are likely to die within _____ after passage

Answer 15

30 minutes to 1 hour

Question 16

Acceptable temperature of refrigerator for stool samples

Answer 16

3-5C (most optimal = 4C)

Question 17

An all-purpose fixative that can be an eye irritant

Answer 17

Formalin

Question 18

Concentration of formalin recommended for protozoan cysts

Answer 18

5%

Question 19

Concentration of formalin recommended for helminth eggs and larva

Answer 19

10%

Question 20

When using formalin as a fixative, the stool must be fixed within how many minutes?

Answer 20

30 minutes

Question 21

This fixative has Mercuric chloride in its stock solution, which is why it is often regarded as a dangerous fixative

Answer 21

Schaudinn’s solution

Question 22

Best option for permanent staining

Answer 22

Mercuric chloride

Question 23

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

Answer 23

Polyvinyl alcohol (PVA)

Question 24

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

Answer 24

Polyvinyl alcohol (PVA)

Question 25

True or false. For modified PVA, copper is preffered over zinc

Answer 25

False

Question 26

Function of iodine in Merthiolate-Iodine-Formalin (IMF)

Answer 26

Stain

Question 27

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

Answer 27

Merthiolate-Iodine-Formalin (IMF)

Question 28

Not suitable for permanent smears stained with trichrome

Answer 28

Merthiolate-Iodine-Formalin (IMF)

Question 29

Interferes with other stains and fluorescence; may cause distortion of protozoa

Answer 29

Iodine in IMF

Question 30

Has glacial acid that helps lyse the cells and albumin-glycerol which sticks the sample to the slide

Answer 30

Sodium acetate-acetic acid formalin (SAF)

Question 31

What fixatives can be used for direct wet mount preparation?

Answer 31

Formalin, MIF, SAF

Question 32

What fixatives can be used for concentration procedures?

Answer 32

Formalin, MIF, SAF

Question 33

What fixatives can be used for permanent staining?

Answer 33

Schaudinn’s solution, PVA, Modified PVA, SAF

Question 34

Predominant stage in watery sample

Answer 34

Trophozoites (processed within 30-60 mins)

Question 35

Predominant stage in formed sample

Answer 35

Cyst (may be processed for up to 24 hours)