Ziehl-Neelsen stain
The Ziehl-Neelsen stain was first described by two german doctors; Franz Ziehl (1859-1926), a bacteriologist and Friedrich Neelsen (1854-1894), a pathologist. It is a special bacteriological stain used to identify acid-fast mycobacteria. It can also be used to stain few other bacteria like Nocardia. The reagents used are Ziehl-Neelson carbol fucshin, acid alcohol and methylene blue.
Procedure
- Add Ziehl-Neelson carbol fucshin to the slide for five minutes while applying heat.
- This is followed by a gentle wash with water to cool the slide.
- Acid alcohol is now added to decolorize the slide.
- Wash the slide in water again and counterstain with methylene blue for one to two minutes.
- The acid-fast bacteria retain the red color, and are therefore seen red against a blue background.