Lab safety and Specimen Collection, Handling and Disposal

Question 1

the key in the laboratory

Answer 1

Safety

practice preventive measures to prevent any infections

Question 2

• Potential Risks

Answer 2

Ingestion of eggs / ova
skin penetration of infective larva
infection of non-parasitic agent

Question 3

Mode of transmission of parasites

Answer 3

ingestion of eggs

Question 4

most infective stage of parasite

Answer 4

eggs/ova

Question 5

Examples of larvae that can penetrate skin

Answer 5

Filariform larvae / Hookworm

Cercaria / Schistozomes

Question 6

TRUE OR FALSE

Fixed stool specimens may still be infectious

Answer 6

TRUE

Question 7

Examples of parasites that are infectious even when preserved with formalin

Answer 7

Ascaris Lumbricoides / Giant intestinal round worm

Question 8

Most common fixative / presevative

Answer 8

Formalin

Question 9

Fecal specimen is best collected in

Answer 9

Clean, wide-mouthed containers made of waxed cardboard or plastic with a tight-fitting lid

Question 10

Reason for the collection container of fecal specimen

Answer 10

to ensure retention of moisture and to prevent accidental spillage

Question 11

Drugs that can interfere with the detection and diagnosis of parasitic infection

Answer 11

• Antacids
  
  • Anti-diarrheals
  • barium
  • bismuth
  • Laxatives

Question 12

Antacids, Anti-diarrheals, barium, bismuth and Laxatives can cause

Answer 12

FALSE NEGATIVE result

Question 13

If a person has ingested laxative drugs, he should collect stool samples:

Answer 13

7 days / a week after last intake

Question 14

Intake of antibiotics can cause

Answer 14

FALSE NEGATIVE

Question 15

What happens when a person take antibiotics

Answer 15

decreases the number of protozoans (unicellular) for several weeks

Question 16

Most challenging parasite to identify

Answer 16

Protozoan parasite (Unicellular)

Question 17

Amount of stool to be collected in routing stool examination

Answer 17

Formed stool : thumb size

Water stool : about 5-6 tablespoons

Question 18

Contamination of these 3 should be avoided

Answer 18

Toilet water, urine, soil

Question 19

What happens when specimen is contaminated with toilet water, urine and soil

Answer 19

Can destroy protozoan trophozoites as they may contain free-living organisms that can complicate diagnosis

Question 20

Age of stool sample if very important for

Answer 20

diarrhetic specimens

Question 21

Protozoan trophozoites are commonly seen in

Answer 21

watery sample

Question 22

watery sample containing protozoan trophozoites must be processed

Answer 22

30 mins to 1 hour after passage

Question 23

Protozoan cysts are commonly seen in

Answer 23

formed sample

Question 24

Formed sample with protozoan cyst must be processed

Answer 24

within 24 hrs

Question 25

If examination of specimens will be delayed it must be

Answer 25

preserved to ensure that parasites are present in the identifiable stage

Question 26

Preserving the specimen is done to

Answer 26

prevent degradation of parasites

Question 27

Temporary storage of fecal sample is

Answer 27

in refrigerator

Question 28

prolonged refrigeration can cause

Answer 28

Desiccation

Question 29

In refrigeration these parasites are usually not damaged

Answer 29

Helminth eggs and protozoan cyst

Question 30

In temporary storage what must never be done

Answer 30

never freeze stool samples | Never keep them in incubators

Question 31

- all purpose fixative / preservative to prevent degradation

Answer 31

Formalin

Question 32

- cheapest and most common fixative

Answer 32

Formalin

Question 33

- May be buffered with sodium phosphate to preserve the morphological characteristics of organisms

Answer 33

Formalin

Question 34

Preserved stool can be concentrated using

Answer 34

formal-ether/ ethyl acetate concentration technique (FECT)

Question 35

In FECT samples should be

Answer 35

formalinized

Question 36

Advantage and disadvantage of Formalin

Answer 36

Cheapest | Not used for permanent staining

Question 37

5% conc formalin

Answer 37

protozoan cyst

Question 38

10% conc formalin

Answer 38

helminth eggs and larvae

Question 39

- Used to preserve FRESH STOOL in preparation for staining the STOOL SMEARS

Answer 39

Schaudinn's solution

Question 40

Schaudinn's solution contains highly toxic substance

Answer 40

Mercuric chloride

Question 41

Advantage and disadvantage of Schaudinn's

Answer 41

Recommended for permanent staining | Very toxic because of mercuric chloride

Question 42

- Partner of Schaudinn’s solution

Answer 42

Polyvinyl alcohol (PVA)

Question 43

- A plastic resin that serves to adhere a stool sample onto a slide

Answer 43

Polyvinyl alcohol (PVA)

Question 44

TRUE OR FALSE | Stools preserve in PVA can be concentrated using FECT

Answer 44

True

Question 45

Advantage and disadvantage of PVA

Answer 45

related to preservation of protozoan cysts and trophozoites for permanent staining use of mercuric chloride

Question 46

Merthiolate-iodine-formalin (MIF) / Thiomersal

Answer 46

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

Question 47

In MIF what preserves and what stains

Answer 47

Preserves / FIxates : Formalin | Stains : Iodine

Question 48

Used as substitute for permanent staining

Answer 48

Sodium acetate-acetic acid formalin (SAF)

Question 49

Images fixed in SAF are

Answer 49

not as sharp as those fixed in PVA and Schaudinns

Question 50

Liquid Fixative with long shelf life

Answer 50

Sodium acetate-acetic acid formalin (SAF)

Question 51

Container with stool preservative for protozoan trophozoites

Answer 51

Modified Cupric Sulfate - PVA