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

1. Add Ziehl-Neelson carbol fucshin to the slide for five minutes while applying heat.
2. This is followed by a gentle wash with water to cool the slide.
3. Acid alcohol is now added to decolorize the slide.
4. Wash the slide in water again and counterstain with methylene blue for one to two minutes.
5. The acid-fast bacteria retain the red color, and are therefore seen red against a blue background.