auramine

Auramine is a fluorescent dye used in microbiology to detect acid-fast bacteria. The term commonly refers to auramine O, a basic fluorochrome that is often used in combination with rhodamine as the auramine-rhodamine stain. When bound to the waxy cell walls of mycobacteria, the dye emits bright yellow to green fluorescence under blue- or near-ultraviolet light, allowing easy visualization against a dark background.

In diagnostic practice, specimens such as sputum are stained with an auramine O solution, decolorized with acid-alcohol, and examined under a fluorescence microscope. Acid-fast organisms glow brightly, while non–acid-fast material remains comparatively nonfluorescent. This method is generally more sensitive than traditional Ziehl-Neelsen staining and enables rapid screening for mycobacterial infection, though it can yield false positives from debris and requires appropriate equipment and training.

Auramine staining is widely used to detect Mycobacterium tuberculosis and other acid-fast bacteria, and is commonly employed as a screening tool in clinical microbiology labs. Results are typically confirmed with additional tests, such as culture or molecular methods, to establish species identification and drug susceptibility.

Safety and handling considerations include that auramine dyes are hazardous chemicals. They should be stored protected from light and handled with appropriate personal protective equipment and ventilation. Proper disposal of stained slides and chemical waste must follow institutional and regulatory guidelines.