Ziehl Neelson Stain for Acid Fast Bacilli

Solutions required

1. Strong carbol fuchsin
2. Acid alcohol - 1% hydrochloric acid in 70% alcohol
3. Methylene blue - 0.1% aqueous

Method

1. Heat fix smear by passing through Bunsen flame ~ 3 sec
2. Flood slide with carbol fuchsin solution and heat until steaming - 10 min
3. Rinse with water
4. Decolourise in acid alcohol - 1 to 2 min
5. Rinse with water
6. Counterstain with methylene blue - 30 sec
7. Rinse with water
8. Blot dry and examine under oil immersion

Results

• Acid fast bacilli - Red
• Background and other organisms - Blue