acidfastfärgningens

Acid-fast staining is a differential staining technique used in microbiology to identify bacteria that have a waxy cell wall, specifically those containing mycolic acids. This unique property makes them resistant to decolorization by acids or alcohols, hence the term "acid-fast." The most common application of this staining method is the identification of Mycobacterium species, including Mycobacterium tuberculosis, the causative agent of tuberculosis.

The procedure typically involves the use of a primary stain, such as carbolfuchsin, which is applied to the bacterial smear and then heated to facilitate penetration through the waxy cell wall. Following this, a decolorizing agent, usually an acid-alcohol solution, is used. Acid-fast bacteria will retain the carbolfuchsin stain and appear red or pink. Non-acid-fast bacteria, lacking the waxy component, will be decolorized and then take up a counterstain, typically methylene blue, appearing blue or green.

Another important acid-fast genus is Nocardia. The resistance to decolorization is the key characteristic that distinguishes acid-fast organisms. This staining method is crucial for the initial diagnosis and presumptive identification of mycobacterial infections in clinical laboratories, guiding further diagnostic steps and treatment. Variations of the acid-fast stain exist, such as the Kinyoun method, which does not require heating but uses a higher concentration of carbolfuchsin and phenol.