Staining aims to visualize bacteria that are very tiny and also devoid of any color. Staining procedures are meant to give color to the organisms to make it easier to see them under the microscope.
Procedures:
1. Simple Stains - make use of single dye which can either be water-or-alcohol-based. It is used primarily to color the organism and demonstrate its shape and basic structures. Examples are crystal violet, carbon fuchsin, methylene blue, and saffranin.
2. Differential Stains - used to differentiate one group of bacteria from another group.
Types:
1) Gram Stain - distinguishes gram-positive bacteria from gram-negative bacteria.
•Gram-positive bacteria stain purple or blue while gram-negative bacteria stain red or pink.
•Examples of Gram-positive bacteria are all cocci bacteria except for Neisseria, Veillonella, and branhamella. Examples of Gram-negative bacteria are all bacilli except for Corynebacterium, Clostridium, Bacillus, and Mycobacterium.
2) Acid-Fast Stain - stain used for those bacteria with a high lipid content in their cell wall.
Methods:
•Ziehl-Neelsen Stain - known as "hot method" because it requires steam-bathing the organism with the aqueous dye.
•Kinyoun Stain - known as "cold method", as it does not utilize heat for staining.
