What does it mean when aculture is acid fast?
Principle: Some bacteria contain a waxy lipid, mycolic acid, in there cell wall. This lipid makes the cells more durable and is commonly associated with pathogens. Acid fast cell walls are so durable that the stain (carbol fuschin) must be driven into the cells with heat. The cells are then decolorized with acid-alcohol, all other cells will decolorize with this strong solvent, but acid fast bacteria will not.