ZiehlNeelsenFärbungen

ZiehlNeelsenFärbungen refers to a differential staining technique used in microscopy, most commonly for the identification of acid-fast bacilli. Acid-fast bacteria are a group of bacteria that, once stained, resist decolorization by acids. This characteristic is primarily due to the high mycolic acid content in their cell walls.

The ZiehlNeelsen staining procedure involves several key steps. First, a heat-fixed smear of the sample is treated with a concentrated solution of carbolfuchsin, a primary stain, and heated to allow the stain to penetrate the waxy cell wall. Following this, the smear is decolorized with an acid-alcohol solution. Non-acid-fast bacteria, lacking the significant mycolic acid content, will be decolorized at this stage. Acid-fast bacteria, however, retain the carbolfuchsin stain. The smear is then counterstained, typically with methylene blue. This counterstain colors the non-acid-fast bacteria and the background material, making the red, acid-fast bacilli stand out clearly under the microscope.

This staining method is particularly important in the diagnosis of tuberculosis, caused by Mycobacterium tuberculosis, which is an acid-fast organism. It is also used for identifying other mycobacteria and some species of Nocardia. While effective, the ZiehlNeelsen technique can be time-consuming and requires careful control of heating and decolorization steps to achieve accurate results. Variations of this method exist, such as the Kinyoun stain, which does not require heating but uses a more concentrated carbolfuchsin solution.