TABLE 1.

Initial drug susceptibility results for 82 clinical strains of M. tuberculosis as determined by the MB/BacT and BACTEC MGIT 960 methods in comparison with the BACTEC 460TB system^a

System and phenotype	No. of strains with the indicated phenotype as determined by the BACTEC 460TB method
	INH		RIF		EMB		STR
	R	S	R	S	R	S	R	S
MB/BacT
R	47	2	14	1	9	0	12	0
S	1	32	0	67	3	70	6	64
BACTEC MGIT 960
R	45	0	14	1	11	0	17	3
S	3	34	0	67	1	70	1	61

^aDrug concentrations used for MB/BacT and MGIT 960 testing were 0.1 μg/ml for isoniazid, 1 μg/ml for rifampin, 5 μg/ml for ethambutol, and 1 μg/ml for streptomycin. Drug concentrations used for BACTEC 460TB testing were 0.1 μg/ml for isoniazid, 2 μg/ml for rifampin, 7.5 μg/ml for ethambutol, and 6 μg/ml for streptomycin. INH, isoniazid; RIF, rifampin; EMB, ethambutol; STR, streptomycin; S, susceptible; R, resistant.