Lab Test 2 4/28/15

Question 1

Which genera of parasites can be detected and identified by examination of a peripheral blood smear?

Answer 1

Leishmania, Plasmodium, Trypanosoma, Loa, Brugia, and Babesia

Question 2

What are the four components of the procedure for the laboratory examination of a stool specimen for ova and parasites?

Answer 2

Macroscopic exam, direct microscopic exam, concentration, permanent stain smear

Question 3

Name the two procedures commonly used for the concentration of a stool specimen and give the principle of each procedure

Answer 3

Formalin-ethyl acetate, sedimentation; zinc-sulfate, floatation

Question 4

Why is it useful to perform the direct examination of a stool specimen using both saline and iodine

Answer 4

Saline: used to view anything motile, especially helminth eggs.
Iodine: used to observe cyst of protozoa. Darkens nuclei of cyst of protozoa (to see how many)

Question 5

Name several artifacts that can be found in ova and parasite preparations.

Answer 5

Plant fibers, pollen rains, meat fibers, epithelial cells, Charcot-Leyden crystals, and WBCs

Question 6

What is a scotch tape preparation and for what organism is it used?

Answer 6

Enterobius vermicularis (pinworms); touch stick surface to anal opening of child at bedtime or before waking. Used to collect eggs from perianal area

Question 7

How soon after collection should a semi-solid or liquid stool be examined?

Answer 7

Within 30 minutes of passage

Question 8

If a formed stool cannot be examined on the day of collection,
what steps should be taken?

Answer 8

Put specimen in preservative within 30 minutes and refrigerate

Question 9

What stage of a protozoan (cyst or troph) is most likely to be seen in a liquid stool?

Answer 9

Troph

Question 10

What stage of a protozoan (cyst or troph) is most likely to be seen in a formed stool?

Answer 10

Cyst

Question 11

What fixative should be used with a liquid stool?

Answer 11

PVA (poly vinyl alcohol)

Question 12

what fixative should be used with a formed stool?

Answer 12

10% formalin

Question 13

What type of container is best to use for the collection and transporting of a stool specimen?

Answer 13

Clean and dry, does not need to be sterile

Question 14

Name several specimens other than stools that might be examined for ova and parasites.

Answer 14

Duodenal aspirates, perianal swabs, sputum, urine, blood, tissue biopsy

Question 15

What are Charcot-Leyden crystals?

Answer 15

Artifacts found in stool specimens, spindle shaped structures

Question 16

What is Charcot-Leyden crystals significance?

Answer 16

Indicates inflammation, parasitic infections, or allergic reactions

Question 17

Of what are Charcot-Leyden crystals thought to be composed?

Answer 17

Ruptured eosinophil granules

Question 18

Name several species of protozoa that have “emerged” as significant pathogens in recent years due to the spread of AIDS.

Answer 18

Pneumocystis carinii, Cryptosporidium, Toxoplasma gondii