Clinical Bacteriology - Laboratory - Differential Staining

Differential stain

What type of stain is gram staining?

Crystal violet, Gram's iodine, Acetone alcohol, Safranin

Enumerate the staining reagents in chronological order

Primary staining, Mordant, Decolorization, Counterstaining

Enumerate the steps of staining in chronological order

Purple

Crystal violet color

Primary stain

Purpose of Crystal violet

Mordant

Purpose of Gram's iodine

Decolorizer

Purpose of Acetone alcohol

Counterstain

Purpose of Safranin

Crystal violet

Stain used for primary staining

Gentian violet

Alternative for crystal violet in primary staining

Hexamethyl-para-rosaniline chloride

Crystal violet chemical name

60 seconds

Primary staining duration in seconds

Gram's iodine

Reagent used for Mordant

60 seconds

Mordant duration in seconds

Mordant

This bridges the primary stain to the cell wall of the organism

Brown

Gram's iodine color

Mordant

This intensifies the stain in the cell wall of a gram-positive organism

Acetone alcohol

Reagent used in decolorization

Differentiation

Other name for decolorization step

5 seconds

Max amount of time for decolorization

Colorless

Acetone alcohol color

Safranin

Stain used for counterstaining

45 seconds

Counterstaining duration

Secondary stain

Other name for counterstain

Red

Safranin color

Thick peptidoglycan layer in its cell wall

What is responsible for the gram staining reaction of Gram-positive organisms?

Thin peptidoglycan layer in its cell wall

What is responsible for the gram staining reaction of Gram-negative organisms?

Heat fixation

This step opens the cell wall of the organism prior to staining

Crystal violet-Iodine complex

It is the complex formed when the mordant is added to crystal violet (primary stain).

Counterstain

What stain is washed off from Gram-positive organisms?

Gram-negative

Which organism's cell wall, based on their gram-staining reaction, has bigger holes during the decolorization step? Causing the CV-I complex to escape.

Thick peptidoglycan layer with teichoic acid

Gram-positive organism cell wall description

Insoluble to alcohol

What is the characteristic of gram-positive cell walls that cause them to retain their primary stain?

Disaccharides, amino acids

Composition of Gram-positive cell wall

Amino acids

Which component of the gram-positive cell wall is insoluble to alcohol?

Lipopolysaccharides, peptidoglycan

What are the outer and inner layers of a Gram-negative cell wall?

Peptidoglycan

What is the inner layer of a gram-negative cell wall made of?

Lipopolysaccharides

What is the outer layer of a gram-negative cell wall made of?

Gram-negative

Most antibiotic resistant are (What gram-staining reaction?) because of their cell wall

Soluble to alcohol

What is the characteristic of gram-negative cell walls that causes primary stains to be washed off?