Define Ziehl-Neelsen Staining Technique?

Ziehl-Neelsen staining is used for staining these bacteria. The technique was discovered first by Robert Koch during his pioneering investigations on tuberculosis and was the fore-runner of Ziehl-Neelsen stain used today for diagnosis of these organisms in laboratory. Acid fast bacteria are called so because once these cells get stained with basic fuchsin, these resist decolourization with acid alcohol as can be seen in margin illustiation. This acid fastness red stain is due to high lipid content particularly of mycolic acid in their cell wall. Mycolic acid, is a group of branched chain hydroxyl lipids, which bind covalently to peptidoglycan of cell wall giving the cell surface a waxy, hydrophobic consistency.