Which of the following are AFB positive with 5% sulphuric acid -
- M. avium
- M. leprae
- M. tuberculosis
M. leprae is less acid fast than M. tuberculosis. Hence 5% sulfuric acid instead of 20% is employed for decolourisation after staining with carbol fuschin.
ACID FAST STAINING
- After staining with aniline dye, acid fast organisms resist decolourisation with acids.
- Method most commonly used is modified Ziehl Neelsen.
Acid fastness depends upon
- Mycolic acid
- Integrity of cell wall