<prompt> Which of the following are AFB positive with 5 sulphuric acid -M. aviumM. lepraeM. tuberculosisNocardia  <response>: Procedure : 1. The smear is stained by a strong solution of carbon fuchsin with the application of heat 2. It is then decolorized with 20 SULPHURIC ACID and counterstained with a contrasting dye such as methylene blue 3. The acid-fast bacteria retain the fuchsin color while others take the counterstain Mycobacterium leprae resists decolorization with 5 SULPHURIC ACID Ref: Ananthanarayan panikers Textbook of Microbiology 9th edition pg no 14 