VMC 211: General Veterinary Microbiology (1+1)

STAINING METHODS

• Staining techniques may be broadly classified into simple and differential staining.

Simple staining

• In simple staining basic stains are used to stain the negatively charged particles. Usually the bacterial cell wall components and nucleic acids carry a negative charge which strongly attract the basic stain with the positively charged chromogen.
• The morphology and arrangement of the bacteria are visualized by simple staining. The basic stains commonly used for simple staining are methylene blue, crystal violet and carbol fuchsin.

Differential staining

• Differential staining uses atleast three reagents.
• The first reagent is called primary stain, the second reagent is called a decolourizer and the third one is called counter stain.
• The primary stain imparts colour to all the cells. The decolourizer is used to establish a colour contrast. The counter stain stains the cells that are decolourised.