What are the principles of differential staining?

In differential staining, multiple dyes are used to differentiate between various microorganisms or structures within a sample. Examples include Gram staining and acid-fast staining. Gram staining divides bacteria into two categories based on their cell wall structure. It involves applying crystal violet dye, followed by iodine treatment, an alcohol wash, and then a counterstain with safranin. Gram-positive bacteria retain the violet dye and appear purple under a microscope, while Gram-negative bacteria take up the red safranin and appear pink. Acid-fast staining method targets bacteria with a waxy coating on their cell walls. It involves staining with carbol fuchsin, applying heat, washing with acid-alcohol, and then counterstaining with methylene blue.