Although no definative evidence has been presented, the high lipid content (especially the mycolic acid component ) of mycobacteria is thought to be related to the mechanism of acid fastness. It has long been known that even light mechanical injury to the cell wall will cause them to lose the acid fast characteristic, suggesting that permeation through cell membranes might be an improtant part of the mechanism. Carbol fuchsin is used to stain the slide. Acid alcohol is used to decolorize the slide. It has been sugested that the dye replacement power of the counter stain could be used to decolorize and counter stain at the same time. It has been shown that acid alcohol increases the differentiation obtained, and gives superior results. After decolorization, the slide may be counter stained with methylene blue or brilliant green. The acid fast organisms will appear red while non-acid fast organisms will stain blue or green.
|483A-8oz||Kinyoun Carbol Fuchsin||8 oz.|
|Kinyoun Carbol Fuchsin||1 gallon|
|311A-8oz||Acid Alcohol Decolorizer||8 oz.|
|311A-1gl||Acid Alcohol Decolorizer||1 gallon|
|675A-8oz||Methylene Blue 1%||8 oz.|
|675A-1gl||Methylene Blue 1%||1 gallon|
|460A-8oz||Brilliant Green 1%||8 oz.|
|460A-1gl||Brilliant Green 1%||1 gallon|
Organisms being stained by an acid fast method are usually taken from a solid or liquid medium on (in) which they have been cultured from their original source (e.g. wounds, throat, swabs, sputum, etc.). An aqueous suspension is made, in the case of the solid medium, by taking a small amount of the material and suspending it in a drop of distilled water on a microscope slide. Care should be taken not to make the smear too thick. In the case of a liquid medium, a drop is used directly from the culture container. However, due to the solids from the medium, this method is not always satisfactory. The suspension made by either method is air dried, then "fixed" by passing rapidly through a Bunsen burner flame two or three times. Allow the smear to cool before staining.
Note: Staining times may vary to suit the individual.