Abstract: Objective To observe the mutations of rpsL gene in M.tuberculosis streptomycin-resistant isolates,and to develop a new method for detecting drug resistance.Method Analyzing the mutations of rpsL gene codon 43 in M.tuberculosis clinical isolates with PCR-RFLP.Results M.tuberculosis strain H 37 R V was used as a control.The rpsL gene fragments from 13 drug-sensitive strains could be digested by restriction endonuclease MboⅡ.31(83.8%)of 37 streptomycin resistant strains were not restricted by MboⅡ.2 of 12 non-streptomycin-resistant strains hadn't also sites of MboⅡ.Conclusions Most M.tuberculosis streptomycin-resistant strains could be observed the mutations situated at codon 43 of genes encoding the ribosomal S12 protein (rpsL).PCR-RFLP might become a simple,rapid and reliable means of detecting drug resistance in clinical isolates.

Key words: M.tuberculosis, Drug resistance polymerase chain reaction, Restriction fragment length polymorphism