kaltacidfastFärbung

KaltazidfastFärbung, also known as cold acid-fast staining, is a differential staining technique used in microbiology. It is a variation of the traditional acid-fast staining method, which is primarily employed to identify bacteria with a waxy cell wall, most notably those belonging to the genus Mycobacterium. The key difference in the cold method lies in the temperature at which the staining reagents are applied.

In the standard Ziehl-Neelsen acid-fast staining, heat is used to drive the primary stain, carbolfuchsin, into the cell wall. This heating process can be hazardous and requires specific equipment. The KaltazidfastFärbung, however, omits the heating step. Instead, a higher concentration of carbolfuchsin or a longer exposure time at room temperature is used to achieve penetration of the waxy mycolic acids in the bacterial cell wall.

The staining procedure typically involves applying a primary stain (carbolfuchsin), followed by a decolorizing agent (acid-alcohol), and then a counterstain (methylene blue). Acid-fast bacteria, due to their resistance to decolorization conferred by their mycolic acid-rich cell walls, retain the red color of the carbolfuchsin. Non-acid-fast bacteria, lacking this characteristic, are decolorized and take up the blue color of the counterstain. This method is particularly useful in laboratories where heating equipment is unavailable or when dealing with potentially dangerous specimens where the risks associated with heating are a concern. Despite the modified application, the principle and diagnostic value remain largely the same as the hot method.