Stain Procedure, Principles, and Interpretation

Question 1

Gram Stain

Answer 1

Fix slide with heat or methanol
Flood with crystal violet (1 min) and rinse
Flood with Gram’s iodine (1 min) and rinse
Decolorize and immediately rinse until runoff is clear
Flood with safranin (1 min) and rinse
Air dry

Question 2

Gram Stain Principle and Interpretation

Answer 2

Gram positive organisms have thick peptidoglycan layers in their cell walls, allowing them to retain crystal violet after decolorizing phase and have a purple coloring
Gran negative organisms have thin peptidoglycan layer in their cell walls that get damaged by decolorizer and will leak the crystal violet
In turn they will take up the counterstain (safranin) and have a red/pink coloring

Positive = Purple (Ex. Staph aureus)
Negative = piNk (Ex. E coli)

Question 3

Acid Fast Stain

Question 4

Acid Fast Stain Principle and Interpretation

Question 5

Modified Acid Fast Stain

Question 6

Modified Acid Fast Stain Principle and Interpretation

Question 7

KOH and Calcofluor White

Question 8

KOH and Calcofluor White Principle and Interpretation

Question 9

Trichrome Stain

Question 10

Trichrome Stain Principle and Interpretation

Question 11

Giemsa Stain

Question 12

Giemsa Stain Principle and Interpretation

Question 13

Acridine Orange Stain

Question 14

Acridine Orange Stain Principle and Interpretation

Question 15

Pneumocystis Stain

Question 16

Pneumocystis Principle and Interpretation