Auramine phenol stain explained

Auramine phenol stain is a stain used in clinical microbiology and histology to identify tuberculosis mycobacteria.

There are two types of auramine phenol stains, 1 and 2 to stain mycobacterium species and cryptosporidium respectively. Both are fluorescent stains. The bacteria or the parasites appear brilliant greenish yellow against dark background.^[1] Mycolic acids of the mycobacteria keep this stain when decolorising with the acid alcohol. The method is more rapid and sensitive than ZN technique.^[2]

Method

• Smears are prepared just like that for ZN staining
• Stain with Auramine-Phenol for 20 mins
• Rinse with water
• Decolourise in acid alcohol
• Rinse with water
• Counterstain with 0.1% potassium permanganate for 30 seconds
• Rinse and air dry^[3]

Notes and References

1. Web site: Microbiology training log. 19 November 2012.
2. Web site: Comparison of the value of two different sputum staining for diagnosis of acid-fast bacilli. 19 November 2012.
3. Web site: Parasitology stains . 19 November 2012 . dead . https://web.archive.org/web/20110410183546/http://www.diasys.com/products/parasitology/fixatives-reagents-and-stains/parasitology-stains/ . 10 April 2011 .