Auramine–rhodamine stain

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

The auramine–rhodamine stain (AR) is a lab method used to see acid-fast bacteria, especially Mycobacterium, under a fluorescence microscope. When present, these bacteria glow reddish-yellow. AR staining is cheaper and more sensitive than Ziehl–Neelsen staining, so it’s often used as a screening test, though it’s less specific and may pick up non-target organisms. The stain is a mix of auramine O and rhodamine B. It is carcinogenic and should be handled with care.