Abstract: Objective To evaluate the significance of DNA sequencing and PCR-SSCP in susceptibility analysis of M.tuberculosis to rifampin.Methods Analyzed the susceptibility to refampin of 25 rifampin-sensitive and 41 rifampin-resistant clinical isolates of M.tuberculosis by DNA sequencing and PCR-SSCP.Results No mutation was found in 25 rifampin-sensitive strains by DNA sequencing.while 38 of 41 rifampin-resistant strains had mutations in rifampin resistant determination region (RRDR) of rpoB gene,the mutation rate was 92.7%(38/41);25 rifampin-sensitive strains had same PCR-SSCP gel profile with M.tuberculosis H₃₇R_v,while 38 of 41 rifampin-resistant strains showed different SSCP profile that could differentiate its from control,indicating the possible existence of sequence alterations in the region of rpoB gene.The accordance rate of DNA sequencing and PCR-SSCP was 93.9%(62/66),compared with DNA sequencing,the sensitivity of PCR-SSCP was 92.1%(35/38),the specialty of PCR-SSCP was 96.4%(27/28).Conclusion DNA sequencing is valuable in rifampin susceptibility test;PCR-SSCP is useful in rifampin resistance strains screening.

Key words: DNA sequencing, PCR-SSCP, Drug resistance, Mycobacterium tuberculosis