Auramin-o Staining
Auramine is preferred to Ziehl-Neelson staining due to its sensitivity, although it does require a fluorescent microscope and slightly more expensive reagents.
Procedure
Smears are airdried and fixed, using either methanol (3-5 min) or heat.
Auramine-O (1:1000 solution, dissolved in ethanol, phenol, and distilled water) is flooded onto the cells to stain mycolic acid.
After 15 minutes, the slides are washed with tap water and then decolorized using HCl (0.5% in ethanol).
After 3-5 minutes, slides are again washed in tap water before being counterstained with potassium permanganate (0.5%) for 30-60 seconds. Slides are washed for a last time and airdried for 10-45 minutes.
Slides are examined using thes