Which are the Acid-fast organisms ?

•These comprise a group of organisms which, like the gram-positive and gram-negative groups, have been named after staining reaction.

Characteristics: 

This group of rod-shaped bacteria possesses large amounts of mycolic acid in the cell wall.

•The presence of mycolic acid makes the bacteria very difficult to stain, but when heat or other agents are used to force carbolfuchsin into the cytoplasm, the bacteria resist decolorization with a dilute acid-alcohol solution.

•Therefore, they are said to be acid-fast.

•Many bacterial spores exhibit the phenomenon of acid fastness.

•The mycobacteria  falls under this acid-fast organisms and include species in the genus Mycobacterium.

•Many mycobacteria are free-living

 Members: Two notable pathogens which exists in the group are:

5.1: Mycobacterium tuberculosis, the cause of tuberculosis in humans and cattle (bovine TB) and tuberculosis in rodents.

5.2: Mycobacterium leprae, which causes leprosy.