Answer:
The Gram stain is a laboratory test that checks for bacteria at the site of a suspected infection or in certain bodily fluids. It is a differential method of staining used to assign bacteria to one of two groups (gram-positive and gram-negative) based on the properties of their cell walls.
The gram staining procedure involves four major steps:
1. Staining with crystal violet - Flood air-dried, heat-fixed smear of cells for 1 minute with crystal violet staining reagent.
2. Fixing the dye - Add a few drops of Gram’s iodine (mordant) which forms a complex with crystal violet.
3. Applying a decolorizer - Rapid decolorization with alcohol, acetone, or a mixture of alcohol and acetone.
4. Counter-staining - Counterstaining with safranin