Laboratory: Concentration Techniques

Question 1

Used for light parasitic infection, when number of ova or adult worm is found in the feces in minimal portion or number

Answer 1

Concentration Techniques

Question 2

Minimal parasitic infection can result to true-positive in DFS. True or False?

Answer 2

False, minimal parasitic infection results to false-negative in DFS

Question 3

Purpose of Concentration Techniques

Answer 3

Aggregate parasites present into a small volume of the sample and to remove as much debris as possible that might hinder the laboratory technician’s ability to see any parasites present clearly

Question 4

Type of sample used in concentration techniques

Answer 4

Fresh/preserved

Question 5

Two Types of Concentration Technique

Answer 5

Flotation Method
Sedimentation Method

Question 6

In this technique, parasites are less dense than the solutions used and during centrifugation, they float to the surface

Answer 6

Flotation Method

Question 7

Reagents used in Flotation Method

Answer 7

Zinc sulfate
Magnesium sulfate
Brine
Sugar

Question 8

The reagents in Flotation Techniques should have what kind of specific gravity, higher or lower?

Answer 8

Higher

Question 9

How many minutes before parasites distort or shrinkage of cysts and eggs occur?

Answer 9

20 minutes

Question 10

Flotation Techniques are mostly used on what type of parasites?

Answer 10

Nematode eggs (except T. trichiura and C. philippinensis)
Protozoan cysts

Question 11

The ratio or comparison between the density of a certain substance to the density of another substance

Answer 11

Specific Gravity

Question 12

Higher SG, _; Lower SG, _

Answer 12

Higher concentration
Lower concentration

Question 13

Specific Gravity of water

Answer 13

1.00

Question 14

Flotation Technique that uses saturated table salt solution

Answer 14

Brine Flotation Method

Question 15

Components of saturated brine solution

Answer 15

NaCl - 40g
Distilled water - 100mL

Question 16

Eggs of _ and _ become badly shrunken in Brine Flotation Method

Answer 16

Hookworm
Schistosoma

Question 17

Brine Flotation Method is not useful for operculated eggs like Ascaris, Trichinella and Raillietina. True or False?

Answer 17

False, operculated eggs such as Opistorchis, Clonorchis and Heterophyids

Question 18

Ideal Specific Gravity for Flotation Technique

Answer 18

1.18-1.20

Question 19

Who developed Zinc Sulfate Flotation Technique and when?

Answer 19

Faust, 1938

Question 20

Percentage of Zinc Sulfate solution used

Answer 20

33%

Question 21

Most widely-used reagent

Answer 21

Zinc Sulfate Solution

Question 22

To ensure detection of all possible organisms in Zinc Sulfate Flotation Technique, both _ and _ must be examined

Answer 22

Surface film
Sediment

Question 23

SG used for fresh stool in Zinc Sulfate Flotation Technique

Answer 23

1.18

Question 24

SG used for preserved stool in Zinc Sulfate Flotation Technique

Answer 24

1.20

Question 25

Components of Zinc Sulfate Solution

Answer 25

Zinc Sulfate (dry crystal) - 330g Distilled water - 670 mL

Question 26

Type of stool not ideal for Zinc Sulfate Flotation Technique

Answer 26

Fatty stool

Question 27

Zinc Sulfate is what type of solution that causes lysis of parasites?

Answer 27

Hypertonic

Question 28

Considered best for the recovery of coccidian oocysts mainly Cryptosporidium spp

Answer 28

Sheather's Sugar Flotation Technique

Question 29

What solution is used in Sheather' Sugar?

Answer 29

Sugar boiled in phenol

Question 30

SG of sugar boiled in phenol

Answer 30

1.27

Question 31

Cryptosporidium spp. reacts to modified acid-fast stain and turns from _ to _?

Answer 31

Bright-red to purple

Question 32

Specie of Cryptosporidium in animals and humans

Answer 32

C. parvum

Question 33

Specie of Cryptosporidium primarily in humans

Answer 33

C. hominis

Question 34

In this technique, parasites are concentrated in the sediment of the tube following centrifugation and the sediment is examined microscopically

Answer 34

Sedimentation Techniques

Question 35

Reagents in Sedimentation Technique have what type of specific gravity, higher or lower?

Answer 35

Lower

Question 36

In Simple Gravity Sedimentation Technique, this is added to stool to allow parasites to settle down by gravity

Answer 36

Tap water

Question 37

What parasite hatches quickly in tap water?

Answer 37

Schistosoma spp.

Question 38

To prevent hatching of eggs in Simple Gravity Sedimentation Technique, _ is added

Answer 38

NSS (Normal Saline Solution)

Question 39

This solution enhances sedimentation or settling of parasites

Answer 39

Glycerinated water

Question 40

Percentage of glycerin solution in tap water

Answer 40

0.5%

Question 41

Sediments can be preserved in _ or _

Answer 41

5% formol-saline 10% formalin

Question 42

Recommended for the recovery of Trichuris, Capillaria and Schistosoma

Answer 42

Acid Ether Concentration Techniques

Question 43

Used to dissolve albuminous material

Answer 43

Hydrochloric acid

Question 44

Ether is flammable and explosive, it can be replaced with?

Answer 44

Ethyl acetate

Question 45

Dissolves neutral fats/lipids and carbohydrates in stool

Answer 45

Ether or ethyl acetate

Question 46

Percentage of hydrochloric acid in Acid Ether CT?

Answer 46

40%

Question 47

Loss of parasite to the plug of debris and destruction of protozoan cysts is possible in Acid Ether CT. True or False?

Answer 47

True

Question 48

Components of Hydrochloric acid

Answer 48

Concentrated hydrochloric acid - 40mL Distilled water - 60mL

Question 49

Most widely used sedimentation technique. Useful in the recovery of both helminth eggs and protozoan cysts; can be done with formalin-preserved and PVA-preserved samples

Answer 49

Formalin Ether/Ethyl Acetate CT

Question 50

All-purpose fixative

Answer 50

10% formalin

Question 51

Morphology is also better preserved in _ than in _

Answer 51

Formalin than in PVA

Question 52

Sediments from FECT can be stored for a long period of time. True or False?

Answer 52

True

Question 53

Component of 10% Formalin

Answer 53

Concentrated formaldehyde - 10mL Distilled water - 90mL

Question 54

Recommended for the better identification of protozoan cysts

Answer 54

Merthiolate Iodine Formalin Ether Concentration Technique

Question 55

Stain used in MIF Ether CT

Answer 55

Merthiolate and Iodine

Question 56

Components of Lugol's Iodine Solution

Answer 56

Iodine powdered crystals - 5g Potassium iodide - 10mL Distilled water - 90mL

Question 57

Components of Stock Merthiolate Formaldehyde Solution

Answer 57

Distilled water - 50mL Tincture of Merthiolate - 40mL Glycerin - 1mL Formaldehyde - 5mL

Question 58

It is necessary to use _ since this contains eosin which stains protozoan cysts and trophozoites along with iodine

Answer 58

Thimerosal or Tincture of Merthiolate

Question 59

Sedimentation techniques are also known as

Answer 59

Indirect Wet Mount

Question 60

Size of coverslips

Answer 60

22x22 mm

Question 61

Why are sedimentation methods more recommended?

Answer 61

They are more efficient and easier to perform accurately