How many acid fast organisms are there?
It is impossible to provide an exact answer to this question. The main idea is that acid-fast organisms are difficult to characterize using standard microbiological techniques. Keep in mind the fact that acid-fastness is a physical property of certain bacteria to resist to decolorization by acids during staining procedures. Not too many people know the fact that acid-fast bacteria can be visualized by fluorescence microscopy using specific fluorescent dyes. It is interesting to know that the most popular technique used to identify acid-fast bacteria is the Ziehl-Neelsen stain.