Ziehl neelsen acid fast stain
From WikiLectures
Ziehl-Neelsen Acid Fast Stain[edit | edit source]
Acid-fast staining is intended for acid-resistant bacteria of the genus Mycobacterium and Nocardia. According to Gram, these microorganisms do not stain due to a cell wall that contains lipids with mycolic acids. These lipids do not absorb dyes poorly and must therefore be dyed hot (dyes so absorbed cannot be washed off even by decolorization with solvents containing strong acids (acid resistance) or bases).
Acid-resistant bacteria are colored pink to red with carbolfuchsin. The contrasting background is green or blue.
Ziehl-Neelsen staining procedure:
- Carbolfuchsin is applied to the fixed preparation and heated with a torch (hot dyeing).
- Subsequently, we decolorize the specimen with acid alcohol while tilting the slide.
- Rinse the specimen in running water.
- Then stain the slide with malachite green (or methylene blue) for 30 seconds.
- Rinse the specimen in running water.
- Leave to dry
