Preservatives

Question 1

is an all purpose fixative

Answer 1

Formalin

Question 2

Formalin

5% concentration is recommended for_______

10% concentration is recommended for________

Answer 2

protozoan cysts

helminth eggs and larvae

Question 3

Formalin

The solution may be buffered with_______ to preserve the morphological characteristics of the organisms.

Answer 3

sodium phosphate

Question 4

is used to preserve fresh stool in preparation for staining the stool smears

Contains mercury

Answer 4

Schaudinn’s solution

Question 5

is a plastic resin which serves to adhere a stool sample onto a slide.

Answer 5

Polyvinyl alcohol (PVA)

Question 6

normally incorporated into the Schaudinn’s solution, therefore the actual fixation is done by the Schaudinn’s.

Answer 6

PVA

Question 7

The main advantage of using_____ is related to the preservation of protozoan cysts and trophozoites for permanent staining.

Answer 7

PVA

Question 8

One major drawback of PVA is the use of mercuric chloride. Some laboratory technologists have suggested replacing this compound with____

Answer 8

cupric sulfate

Question 9

MIF

act as staining components

acts as the preservative

Answer 9

merthiolate (also called thimerosal) and iodine

formalin

Question 10

It is useful for the fixation of intestinal protozoans, helminth eggs, and larvae.

Answer 10

MIF

Question 11

component should always be freshly prepared since it is unstable.

Answer 11

Lugol’s iodine

Question 12

Staining of preserved stools in___ yields unsatisfactory results.

Answer 12

MIF

Question 13

has the advantage of not containing mercuric chloride.

Answer 13

Sodium acetate-acetic acid formalin (SAF)

Question 14

Images of organisms fixed in____, however, are not as sharp after staining compared with those fixed in PVA or Schaudinn’s solution.

Answer 14

SAF

Question 15

It is a liquid fixative with a long shelf-life.

Answer 15

SAF

Question 16

Examination of_____ specimens collected every _____is considered the minimum necessary to perform an adequate O & P evaluation

Answer 16

three

other day

Question 17

Examination of three specimens collected every other day is considered the minimum necessary to perform an adequate O & P evaluation (Garcia, 2003; Clinical and Laboratory Standards Institute, 2005). This procedure ensures an optimum interval for recovery of those parasites that are known to shed diagnostic forms intermittently, especially (2)

Answer 17

Giardia lamblia and Strongyloides stercoralis.

Question 18

Additional sensitivity may be achieved in detecting these parasites, as well as Entamoeba histolytica, using____.

Answer 18

purgation