Describing bacteria that have been stained and continue to hold the stain after treatment with an acidic solution. For example, tuberculosis bacteria are acid-fast when stained with a carbol fuchsin preparation.
In bacterial staining, pertaining to bacteria that do not decolorize after application of acid-alcohol but keep a dark stain. Members of the genus Mycobacterium are acid-fast.
One notable attribute exhibited by specific bacteria, particularly those accountable for tuberculosis, is their ability to withstand the acidic properties of the dyes employed to stain specimens during microscopic analysis.
The term used to describe bacteria that are difficult to stain for microscopic observation, but once stained, they retain the stain even when exposed to acids, is known as acid-fast bacteria. The most common example of acid-fast bacteria is the tubercle bacillus.