Parasitology Laboratory Quiz1 Flashcards
Most common procedure performed in the area of Parasitology
Examination of a stool specimen for ova and parasites
Typical stool collection protocol
3 specimens
Up to 6 specimens in 14 days
For amebiasis
Stool sample from patients whose therapy includes?
Barium, Bismuth, or mineral oil
Patient’s whosever in therapy should be collected prior to the therapy or not until?
5 to 7 days after the completions of therapy
For patient’s who have taken antibiotics or antimalarial medication should be delayed for how many weeks?
2 weeks following therapy
Containers for stool collection
Clean, watertight container with a tight-fitting lid
Acceptable amount of stool
2 to 5 g ( often referred to as the size of walnut
According to blank thumb-sized specimen of formed stool 5 to 6 tablespoon of watery stool
Belizario et al
Temporary storage of fecal samples in a refrigerator
3-5 degree celcious is acceptable
Are killed by refrigeration
Trophozoites
Are usually damage
Helminth eggs and protozoan cysts
NEVER
Freeze stool samples
Keep them in incubations
Should not be allowed to be contaminate the stool specimen
Urine
Stool should not be blank from toilet bowl water
Not be retrieved
Used to demonstrate the motility of protozoan trophozoites
Fresh specimens
Should be examined within 30 minutes of passage
Liquid stool
Should be evaluated within 1hour of passage
Semi formed specimen’s
Can be held for 24 hours
Formed stool specimens
Substance that preserve the morphology of protozoa and prevent further development of certain helminth eggs and larvae
Fixatives
5% ideally preserves protozoan cyts
10% preserve’s helminths eggs and larvae
Formalin
Adhesive for the stool when preparing slides for staining
Most often combined with schaudinn solutions
Polyvinyl Alcohol (PVA)
Schaudinn Solutions contains?
Zinc sulfate, copper sulfate or mercuric chloride as a base)
Can be used for performing concentration techniques and permanent stained smears
It is a liquid fixative with long-shell life
Sodium acetate formalin
Other alternatives to mercury- based PVA are the use of substitutes compounds contain copper sulfate or zinc sulfate
Modified polyvinyl alcohol
Free of formalin and mercury and can be used for concentration techniques and permanent stained smears alter
Alternative single vial system’s
contains merthiolate (also called thimerosal) and iodine which act as staining components, while
formalin acts as the preservative
MERTHIOLATE-IODINE-FORMALIN
Determine: color and consistency
MACROSCOPIC EXAMINATION
Consistency or degree of moisture in a stool: can be classified as:
Formed
Semi-formed
Soft
Loose
Watery
Liquid stool
(+) protozoan trophozoites
Fully formed stools
(+) protozoan cysts
Liquid or formed stools
(+) Helminth eggs and larvae
color of the normal stool
Brown
Unusual colors of stools
purple, red or blue
should always be reported.
Presence of blood
responsible for the brown color of the stool
Stercobilin
suggests UPPER GIT Bleeding- esophagus, stomach and duodenum
Dark-colored blood
means LOWER GIT Bleeding ileum, jejunum, large intestine
Bright red blood
found in stool include adult worms, proglottids, pus & mucus
Gross Abnormalities
should be examined for parasites such as pinworms, tapeworm proglottids, and adult
worms
Surface of the stool
may suggest presence of amebic ulcerations in the large intestine
Blood and/or mucus in loose/liquid stool
usually associated with irritation & bleeding
Bright red blood on the surface of a formed stool
3 DISTINCT PROCEDURES: should be performed on a fresh specimen
- Direct Wet Preparations
- Concentrated Technique resulting in concentrated wet preparations
- Permanently stained smear
Main purpose: To detect the presence of motile protozoan trophozoites
o made by placing a drop of 0.85% saline on a glass slide (a 3- × 2-inch size is suggested) and mixing with a
small portion of unfixed stool using a wooden applicator stick or another mixing tool
DIRECT SALINE WET PREPARATION
Small portion of unfixed stool
About 2 mg of stool
is placed on the slide and the preparation is examined microscopically in a
systematic fashion.
22-mm square cover slip
should be scanned using the low power (10×) objective on the microscope,
and the power should only be increased when a suspicious object requires further investigation.
entire cover glass
kills the trophozoites present in a stool specimen.
Iodine
is placed over a glass slide and covered with cut
cellophane paper soaked in a mixture of glycerine and malachite green solution
50 to 60 mg of stool
is a clearing solution and malachite green is used to give color to the cellophane in order to give a pale green background to the eggs and to minimize the brightness of the microscopic field.
Glycerine
