武汉地区结核分枝杆菌链霉素耐药分离株rpsL基因分子特征研究

Molecular characterization of rpsL genes of streptomycin-resistant clinical isolates of mycobacteria tuberculosis in Wuhan

探讨武汉地区结核分枝杆菌链霉素(SM)耐药临床分离株rpsL基因分子特征。收集71株临床分离株,采用刃天青法测定临床分离株对SM的最低抑菌浓度(MIC),同时用直接测序法分析rpsL基因的突变情况;用RD105基因缺失检测法鉴定71株临床分离株中"北京基因型"菌株。结果显示20株SM敏感株rpsL基因未发现突变(MICs<0.25 mg/L);51株SM耐药株中,35株(68.6%)检测到rpsL基因突变,主要发生在第43位和88位密码子,MIC1 mg/L的SM耐药株(低水平耐药株)总突变率低于MIC2mg/L(高水平耐药株);北京基因型与耐药株的相关性不大。研究表明SM耐药菌株rpsL基因突变类型存在地域差异;rpsL突变与SM高水平耐药的相关性在本研究中关联度不大;"北京基因型"菌株在武汉地区呈流行趋势。

To explore the molecular characteristics of the mutations in rpsL genes of streptomycin（ SM）-resistant clinical isolates of Mycobacteria tuberculosis in Wuhan. Resazurin was used to determine the SM minimum inhibitory concentration（ MIC） of 71 clinical isolates and direct sequencing analysis was used to detect rpsL genes,RD105 gene deletion was used to identify the Beijing genotype in the 71 clinical isolates. The results show that no mutation was found in the 20 SM susceptible isolates and the MICs of the 20 SM susceptible isolates were 〈0. 25 mg /L; of the 51 SM-resistant isolates,35（ 68. 6%） carried mutations in rpsL gene,with rpsL Lys43 Arg and Lys88 Arg being the most common rpsL mutations. Among SM-resistant isolates with MIC≤1 mg /L（ low-level resistant） and MIC≥2mg / L（ high resistant）,3 out of 6 and 32 out of 45 isolates carried mutations. Mutations in rpsL gene of SM-resistant isolates varied due to geographical differences; and mutations in rpsL had no associated with SM high-level resistance; in addition,the Beijing genotype were prevalent in Wuhan,which should arouse our attention.