Abstract: Objective To investigate the relationship between drug resistance gene mutation and drug resistance level in M.tuberculosis .Methods 108 M.tuberculosis clinical isolated strains from sputum specimens were tested by PCR-SSCP and traditional drug susceptibility tests.Results The gene mutation rate of SM,RFP and INH resistance clinical isolated strains was 78.5%,68.2% and 70.5% respectively,and the mutation rate of SM,RFP and INH high concentration resistance isolated strains was 86.5%,89.3%,84.3% respectively.But the mutation rate of low level of resistance strains was 28.5%, 16.5% and 7.1%.Conclusion The gene mutation was in relation with drug resistance level of M.tuberculosis .The gene mutation rate was higher in high level of resistance isolated strains than in low level of resistance isolated strains.

Key words: M.tuberculosis, Drug resistance, PCR-SSCP