Cytochrome P-450 in drug-resistant Mycobacterium tuberculosis

Methods for the isolation and spectrophotometric determination of cytochrom e P-450 in mycobacteria were standardized. Cytochrome P-450 levels were est imated in Mycobacterium tuberculosis organisms sensitive to both isoniazid and rifampicin and resistant to any of the two drugs. Cytochrome P-450 was isolated and its presence was shown in M. smegmatis, M. fortuitum, M. chelo nae and M. tuberculosis H(37)Rv. The cytochrome P-450 content was significa ntly elevated in M. tuberculosis, resistant to both isoniazid and rifampici n when compared with the corresponding sensitive strains. It therefore appe ars that cytochrome P-450 might play a role in causing drug resistance in t uberculosis.