(Part 1) 1.13 Gram stain

Question 1

Provides a rapid presumptive identification of pathogens

Answer 1

Gram stain

Question 2

Who devised Gram stain?

Answer 2

Hans Christian Gram

Question 3

Color of Gram neg?

Answer 3

Pink

Question 4

Color of Gram positive

Answer 4

Purple/Violet

Question 5

Reagents of Gram stain?

Answer 5

Crystal violet (10 -30 secs)
Iodine (2x as long as CV)
Acetone (10 sec)
Safranin (30 sec)

Question 6

Fixes primary stain in to the cell wall

Answer 6

Mordant

Question 7

Main target of pimary stain

Answer 7

Peptidoglycan

Question 8

What is the color of gram neg during decolorization?

Answer 8

Clear

Question 9

Crystal violet stains both gram pos and neg?

T or F

Answer 9

T

Question 10

Reason for why Gram negaive washes away primary stain?

Answer 10

Thin peptidoglycan

Contains lipids that can wash away the primary stain when decolorizer is applied

Question 11

What is the counter stain in gram stain?

Answer 11

Safranin

Question 12

Most critical step in gram staining that allows differentiation of gram negative and gram positive?

Answer 12

Decolorization

Question 13

All cocci are Gram positive except?

Answer 13

Neisseria
Veillonela
Moraxela

NVM

Question 14

All bacilli are gram negative except?

Answer 14

Bacillus
Mycobacterium
Actinomycetes
Arcanobacterium
Corynebacterium
Clostridium
Nocardia
Erysipelothrix
Listeria
Lactobacillus
Propionibacterium

BMAACCNELLP

Question 15

Common test perform in the laboratory for gram positive?

Answer 15

Catalase test

Oxidase test

Question 16

Ommision of Crystal violet resulted to?

Answer 16

Pink color

Question 17

Omission of Mordant resulted to?

Answer 17

Pink color

Question 18

Omission of Decolorizer resulted to?

Answer 18

All Violet

Question 19

Omission of Safranin resulted to?

Answer 19

Gram positive: Violet
Gram negative: Clear/Colorless

Question 20

Applying gram stain to old cultures may result to?

Answer 20

Pink color

Because of deterioration of cell wall, Primary stain may not be applied

Question 21

Excessive heat fixation during gram stain may result to?

Answer 21

Pink

Cell wall may be destroyed

Question 22

Over decolorization during gram stain may result to?

Answer 22

Pink

Excessive decolorization may remove all violet colors even in Gram-positive bacteria

Question 23

Excessive washing during gram stain may result in?

Answer 23

Pink/colorless

Regardless of which part of the procedure, excessive washing may remove the bacteria in the stain. or even the primary stain.

Question 24

Gram iodine is acid or alkaline?

Answer 24

Alkaline

Question 25

What to evaluate when examining gram stain in microscope?

Answer 25

Gram Reaction
Morphology
Arrangement
Presence of inflammatory cells

Others:
Squamous
tissue debris
Report absence of bacteria is any

Question 26

How to report the relative amount of bacteria?

Answer 26

Rare, Few, Moderate, Many
1+, 2+, 3+, 4+