Lab Safety and Specimen Collection

Question 1

Potential risks in parasitoloy lab

Answer 1

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

Question 2

True or False: fixed stool specimens in formalin are risk-free and non-infectious because of the fixative

Answer 2

False

Question 3

Has a thick outer layer made up of albumin

Answer 3

Ascaris lumbricoides

Question 4

Container for fecal specimen

Answer 4

Clean, wide-mouthed containers

Question 5

Capacity of fecal containers

Answer 5

0.5 pint or approx. 240 mL

Question 6

How many specimens within how many days should be collected for routine fecalysis?

Answer 6

3 specimens collected within 6-7 days (no more than 7 days)
Every other day is collected

Question 7

How many specimens within how many days should be collected for intestinal amebiasis?

Answer 7

No more than 6 specimens collected within 10 days

Question 8

How many weeks is the patient deferred from fecalysis if they are taking anti-protozoan drugs?

Answer 8

3-4 weeks

Question 9

How many weeks is the patient deferred from fecalysis if they are taking anti-helminthic drugs?

Answer 9

5-6 weeks

Question 10

Which drugs should be a cause of deferment for 1 week?

Answer 10

o Antacids
o Anti-diarrheals
o Barium
o Bismuth
o Laxatives

Question 11

Usually decreases the number of protozoans for several weeks

Answer 11

Antibiotics

Question 12

Size of formed stool that should be used

Answer 12

thumb-sized

Question 13

How much watery stool should be used

Answer 13

5-6 tablespoons

Question 14

How much time before trophozoites die?

Answer 14

30 minutes - 1 hour

Question 15

What should be the temperature of the refrigerator used for stool samples?

Answer 15

3-5 degrees celsius (4 degrees celsius is the most optimal)

Question 16

Does not preserve morphology (has time limitations)

Answer 16

Formalin

Question 17

Stool to fixative ratio for formalin

Answer 17

1:3

Question 18

Concentration of formalin that is recommended for protozoan cysts

Answer 18

5%

Question 19

Concentration of formalin that is recommended for helminth eggs and larva

Answer 19

10%

Question 20

Percentage of the stock solution of formalin

Answer 20

40%

Question 21

What solution can buffer formlin to preserve morphological characteristics of organisms

Answer 21

Sodium phosphate

Question 22

Morphology is preserved but not motility

Answer 22

Schaudinn’s solution

Question 23

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

Answer 23

Schaudinn’s solution

Question 24

Contains mercuric chloride (highly toxic to humans; problems of mercury disposal may arise)

Answer 24

Schaudinn’s solution

Question 25

The best option for permanent staining

Answer 25

mercuric chloride

Question 26

Not a fixative but an adhesive

Answer 26

Polyvinyl alcohol (PVA)

Question 27

o Normally incorporated into the Schaudinn’s solution (actual fixation is done by the Schaudinn’s)

Answer 27

Polyvinyl alcohol (PVA)

Question 28

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

Answer 28

Polyvinyl alcohol (PVA)

Question 29

Combination of fixative and temporary stain

Answer 29

Merthiolate-Iodine-Formalin (IMF)

Question 30

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

Answer 30

Merthiolate-Iodine-Formalin (IMF)

Question 31

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

Answer 31

Sodium acetate-acetic acid formalin (SAF)

Question 32

Has the advantage of not containing mercuric chloride

Answer 32

Sodium acetate-acetic acid formalin (SAF)

Question 33

not as sharp after staining compared to PVA or Schaudinn’s solution

Answer 33

Sodium acetate-acetic acid formalin (SAF)

Question 34

A liquid fixative with a long shelf-life

Answer 34

Sodium acetate-acetic acid formalin (SAF)

Question 35

What type of stool sample should be used for direct stool examination?

Answer 35

fresh sample

Question 36

What type of stool sample should be used for concentration methods?

Answer 36

Preserved and fresh sample

Question 37

What type of stool sample should be used for permanent smear?

Answer 37

preserved sample

Question 38

Possible observation of trophozoites motility

Answer 38

Fresh stool

Question 39

Can be used for direct wet exam, concentration methods, permanent staining, immunoassays, special staining, etc.

Answer 39

Fresh stool

Question 40

Presents good morphology of the organism as some preservative may alter the morphology of parasites

Answer 40

Fresh stool

Question 41

May have excessive lag time between stool fixation or processing

Answer 41

fresh stool

Question 42

Organism morphology is preserved when lag time between stool passage and fixation is short

Answer 42

preserved stool

Question 43

How much time is permitted to process a watery sample?

Answer 43

30-60 mins

Question 44

How much time is permitted to process a formed sample?

Answer 44

up to 24 hours

Question 45

What is predominant in formed sample?

Answer 45

Cysts

Question 46

What is predominant in watery sample?

Answer 46

trophozoites

Question 47

What consistency of stool samples has equal amounts of trophozoites and cysts?

Answer 47

soft & loose