What is the order of reagents used in the Gram stain?
Answers
The Gram stain is now used to differentiate intact,
morphologically similar bacteria into two groups based on cell color after
staining. In addition, cell form, size and structural details are evident. Such
preliminary information provides important clues to the type of organism
present and the further techniques required to characterize them.
Crystal Violet (primary stain) = stains bacterial
cell
Iodine = mordant, bind the stain
Alcohol-acetone = differentiates bacteria by
retaining or not crystal violet, within their cell wall
Safranin = counter stain for some fastidious
microorganisms. This will dye the colorless cells.
Gram positive = the cells that retain the primary
stain will appear blue or purple
Gram negative = Cells that stain with the counterstain
will appear pink or red
iodine
decolorizer
safranin