LESSON#2: SPECIMEN COLLECTION AND PROCESSING

Question 1

should be examined within 1 hour of passage

Answer 1

Fresh specimen

Question 2

should be examined within 30 minutes

Answer 2

liquid specimen

Question 3

How long does formed or semi-formed stool should be used

Answer 3

Within 3-4 hours

Question 4

How long does watery stool should be used

Answer 4

30 minutes

Question 5

the motile stage of protozoans and are found in liquid samples. This is
more sensitive and fragile and must be processed within 30
minutes.

Answer 5

Trophozoites

Question 6

Common for intestinal parasites (protozoans and metazoans)

Answer 6

Fecal specimens

Question 7

Type of container to be used for fecal specimen

Answer 7

Screw cap tight fitting containers and Wide mouth containers for retention of moisture and prevent spillage

Question 8

Parasites detected in fecal sample

Answer 8

○ Cyst
○ Trophozoites
○ Oocyst
○ Eggs
○ Larvae
○ Adult worm

Question 9

most common examination method for fecalysis

Answer 9

Wet mount technique (Direct fecal smear)

Question 10

EXAMINATION OF FECAL SPECIMENS FOR ANTIGEN DETECTION

Answer 10

Immunoassay

Giardia spp.
Cryptosporidium spp.
Entamoeba histolyca

Question 11

SUBSTANCES THAT INTERFERE WITH STOOL SAMPLES

Answer 11

1. Urine samples - toxic to trophozoite
2. Barium, bismuth, kaolin, milk – crystalline particles
3. Antibiotics/antimalarials – diarrhea, quality of sample
4. Castor or Mineral Oil – oil droplets, can be an artifact, or may cause confusion
5. Enemas

Question 12

Recommended Ratio of Fixative to Stool

Answer 12

3:1

Question 13

6 Stool Preservatives

Answer 13

○ Formalin
○ Schaudinn’s Solution
○ Polyvinyl alcohol (PVA)
○ Sodium Acetate Formalin (SAF)
○ Modified PVA
○ Two-Vial System

Question 14

An all purpose fixative but not for permanent staining. A
5% concentration is recommended
for protozoan cysts, while a 10%
concentration is recommended
for helminth eggs and larvae.

Answer 14

Formalin

Question 15

used to
preserve fresh stool in preparation for
permanently staining the stool smears. It contains
mercuric chloride which is highly
toxic to humans.

Answer 15

Schaudinn’s solution

Question 16

a plastic
resin which serves to adhere a stool
sample onto a slide. It is normally
incorporated into the Schaudinn’s
solution

Answer 16

Polyvinyl alcohol (PVA)

Question 17

useful for
the fixation of intestinal protozoans,
helminth eggs, and larvae. Contains merthiolate and iodine which act as
staining components

Answer 17

Merthiolate-iodine-formalin (MIF)

Question 18

● Used for permanent stains, direct mounts and concentration procedures
● Does not contain mercury
● Quality is not good

Answer 18

SODIUM ACETATE-ACETIC AICD FORMALIN (SAF)

Question 19

● One portion of specimen is fixed in three parts of 5%-10% buffered formalin
● One portion in three parts of polyvinyl alcohol (PVA) fixative

Answer 19

TWO VIAL TECHNIQUE