Laboratory: Concentration Techniques Flashcards
Used for light parasitic infection, when number of ova or adult worm is found in the feces in minimal portion or number
Concentration Techniques
Minimal parasitic infection can result to true-positive in DFS. True or False?
False, minimal parasitic infection results to false-negative in DFS
Purpose of Concentration Techniques
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
Type of sample used in concentration techniques
Fresh/preserved
Two Types of Concentration Technique
Flotation Method
Sedimentation Method
In this technique, parasites are less dense than the solutions used and during centrifugation, they float to the surface
Flotation Method
Reagents used in Flotation Method
Zinc sulfate
Magnesium sulfate
Brine
Sugar
The reagents in Flotation Techniques should have what kind of specific gravity, higher or lower?
Higher
How many minutes before parasites distort or shrinkage of cysts and eggs occur?
20 minutes
Flotation Techniques are mostly used on what type of parasites?
Nematode eggs (except T. trichiura and C. philippinensis)
Protozoan cysts
The ratio or comparison between the density of a certain substance to the density of another substance
Specific Gravity
Higher SG, _; Lower SG, _
Higher concentration
Lower concentration
Specific Gravity of water
1.00
Flotation Technique that uses saturated table salt solution
Brine Flotation Method
Components of saturated brine solution
NaCl - 40g
Distilled water - 100mL
Eggs of _ and _ become badly shrunken in Brine Flotation Method
Hookworm
Schistosoma
Brine Flotation Method is not useful for operculated eggs like Ascaris, Trichinella and Raillietina. True or False?
False, operculated eggs such as Opistorchis, Clonorchis and Heterophyids
Ideal Specific Gravity for Flotation Technique
1.18-1.20
Who developed Zinc Sulfate Flotation Technique and when?
Faust, 1938
Percentage of Zinc Sulfate solution used
33%
Most widely-used reagent
Zinc Sulfate Solution
To ensure detection of all possible organisms in Zinc Sulfate Flotation Technique, both _ and _ must be examined
Surface film
Sediment
SG used for fresh stool in Zinc Sulfate Flotation Technique
1.18
SG used for preserved stool in Zinc Sulfate Flotation Technique
1.20
Components of Zinc Sulfate Solution
Zinc Sulfate (dry crystal) - 330g
Distilled water - 670 mL
Type of stool not ideal for Zinc Sulfate Flotation Technique
Fatty stool
Zinc Sulfate is what type of solution that causes lysis of parasites?
Hypertonic
Considered best for the recovery of coccidian oocysts mainly Cryptosporidium spp
Sheather’s Sugar Flotation Technique
What solution is used in Sheather’ Sugar?
Sugar boiled in phenol
SG of sugar boiled in phenol
1.27
Cryptosporidium spp. reacts to modified acid-fast stain and turns from _ to _?
Bright-red to purple
Specie of Cryptosporidium in animals and humans
C. parvum
Specie of Cryptosporidium primarily in humans
C. hominis
In this technique, parasites are concentrated in the sediment of the tube following centrifugation and the sediment is examined microscopically
Sedimentation Techniques
Reagents in Sedimentation Technique have what type of specific gravity, higher or lower?
Lower
In Simple Gravity Sedimentation Technique, this is added to stool to allow parasites to settle down by gravity
Tap water
What parasite hatches quickly in tap water?
Schistosoma spp.
To prevent hatching of eggs in Simple Gravity Sedimentation Technique, _ is added
NSS (Normal Saline Solution)
This solution enhances sedimentation or settling of parasites
Glycerinated water
Percentage of glycerin solution in tap water
0.5%
Sediments can be preserved in _ or _
5% formol-saline
10% formalin
Recommended for the recovery of Trichuris, Capillaria and Schistosoma
Acid Ether Concentration Techniques
Used to dissolve albuminous
material
Hydrochloric acid
Ether is flammable and explosive, it can be replaced with?
Ethyl acetate
Dissolves neutral fats/lipids and carbohydrates in stool
Ether or ethyl acetate
Percentage of hydrochloric acid in Acid Ether CT?
40%
Loss of parasite to the plug of debris and destruction of protozoan cysts is possible in Acid Ether CT. True or False?
True
Components of Hydrochloric acid
Concentrated hydrochloric acid - 40mL
Distilled water - 60mL
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
Formalin Ether/Ethyl Acetate CT
All-purpose fixative
10% formalin
Morphology is also better preserved in _ than in
_
Formalin than in PVA
Sediments from FECT can be stored for a long period of time. True or False?
True
Component of 10% Formalin
Concentrated formaldehyde - 10mL
Distilled water - 90mL
Recommended for the better identification of protozoan cysts
Merthiolate Iodine Formalin Ether Concentration Technique
Stain used in MIF Ether CT
Merthiolate and Iodine
Components of Lugol’s Iodine Solution
Iodine powdered crystals - 5g
Potassium iodide - 10mL
Distilled water - 90mL
Components of Stock Merthiolate Formaldehyde Solution
Distilled water - 50mL
Tincture of Merthiolate - 40mL
Glycerin - 1mL
Formaldehyde - 5mL
It is necessary to use _ since this contains eosin which stains protozoan cysts and trophozoites along with iodine
Thimerosal or
Tincture of Merthiolate
Sedimentation techniques are also known as
Indirect Wet Mount
Size of coverslips
22x22 mm
Why are sedimentation methods more recommended?
They are more efficient and easier to perform accurately
