Abstract: Objective To analyze the growth and drug resistant characteristics of rifampin-depending Mycobacterium tuberculosis strains (rdm) in BACTEC in order to identify rdm in clinic.Methods The rdm was indentified by the previous L-J cultivation.Suspension (10^-4mg/ml 0.1ml) was inoculated in 7H12 liquid media containing lifampin.Their growth index (GI) was detected by BACTEC and the bacteria in the media were weighted and stained by acid-fast staining.Results The resistance to rifampin was detected in media containing 1～96μg/ml of rifampin.The sensitivity to rifampin was detected in the media containing 384μg/ml of rifampin.The weight of the rdm in the media containing 6,8,10,12 and 24μg/ml was 87、125、116、104 and 65mg respectively,that were marked higher than that of control (35mg).The weight of rdm in the media containing rifampin (192～384μg/ml) was 1.9～3.6 times that of control.The bodies of rdm in the media containing rifampin were larger and deeper stained in the acid-fast staining compared with the control.Conclusion The rdm grows vigorously in media containing rifampin of 6～24μg/ml,but it grows much weakly in the media containing no rifampin.

Key words: M.tuberculosis, Rifampin