3.2 Sample Detection: Staining Part 2

Question 1

What is a wet mount?

Answer 1

sample preparation technique where a small liquid culture containing a microorganism is added to the slide and covered with a glass coverslip

Question 2

What is the purpose of the glass coverslip in a wet mount?

Answer 2

protect the objective and hold microorganism in place

Question 3

What are wet mounts normally used to visualize?

Answer 3

motility and behavior of an organism

Question 4

What is simple staining?

Answer 4

uses a solution of positively charged dye to bind to and stain the negatively charged membrane of the microorganism

Question 5

What are common dyes that are used in simple staining?

Answer 5

methylene blue
crystal violet
safranin
fuchsin

Question 6

What is simple staining usually used to visualize?

Answer 6

size, shape, and arrangement of cells

Question 7

What is negative staining?

Answer 7

use of a negatively charged dye to stain everything except the microorganism

Question 8

What is a common stain used in negative staining?

Answer 8

nigrosin (India ink)

Question 9

What is negative stain contraindicated for and why?

Answer 9

pathogenic samples because it may not kill the microorganism

Question 10

What is acid fast staining also known as?

Answer 10

Ziehl Neelsen stain

Question 11

What is an acid fast stain?

Answer 11

differential stain used to identify bacterial stains showing high degree of resistance to decolorization

Question 12

What is the most common bacteria that uses an acid fast stain?

Answer 12

mycobacterium tuberculosis

Question 13

What dye is used in acid fast staining?

Answer 13

red dye carbolfuchsin

Question 14

What is the structure of the bacteria that will remain red in an acid fast stain after the decolorization wash step?

Answer 14

cells with a thick lipid based protective membrane

Question 15

What is the next step after the decolorization step in an acid fast stain?

Answer 15

counterstaining with methylene blue to stain the non-acid-fast bacterium

Question 16

What samples obtained from patients are normally stained using the acid fast staining technique?

Answer 16

sputum samples

Question 17

What is a glemsa stain?

Answer 17

differential stain often used in clinical settings

Question 18

What is the glemsa stain used for?

Answer 18

blood smears to determine the presence of absence of pathogenic bacteria

Question 19

What colors do the cells in a blood smear appear after a glemsa stain?

Answer 19

human blood cells appear purple and bacterial cells appear pink

Question 20

What is the glemsa stained most often used for to diagnose?

Answer 20

malaria and blood parasites