Kinyoun stain

The Kinyoun method or Kinyoun stain (cold method), developed by Joseph J. Kinyoun, is a procedure used to stain acid-fast species of the bacterial genus Mycobacterium. It is a variation of a method developed by Robert Koch in 1882. Certain species of bacteria have a waxy lipid called mycolic acid, in their cell walls which allow them to be stained with Acid-Fast better than a Gram-Stain. The unique ability of mycobacteria to resist decolorization by acid-alcohol is why they are termed acid-fast. It involves the application of a primary stain (basic fuchsin), a decolorizer (acid-alcohol), and a counterstain (methylene blue). Unlike the Ziehl–Neelsen stain (Z-N stain), the Kinyoun method of staining does not require heating. In the Ziehl–Neelsen stain, heat acts as a physical mordant while phenol (carbol of carbol fuchsin) acts as the chemical mordant. Since the Kinyoun stain is a cold method (no heat applied), the concentration of carbol fuschin used is increased.