应用PCR—直接测序法测定结核分支杆菌rpsL基因突变的研究

目的：了解我国结核分支杆菌耐链霉素（Ｓｔｒｅｐｔｏｍｙｃｉｎ，ＳＭ）分离株ｒｐｓＬ基因突变情况，建立快速检测结核分支杆菌耐药基因型的分子药敏试验方法。方法：通过聚合酶链反应（ＰｏｌｙｍｅｒａｓｅＣｈａｉｎＲｅａｃｔｉｏｎ，ＰＣＲ）－单链构象多态性（Ｓｉｎｇｌｅ－ｓｔｒａｎｄｅｄＣｏｎｆｏｒｍａｔｉｏｎＰｏｌｙｍｏｒｐｈｉｓｍ，ＳＳＣＰ）、ＰＣＲ－限制性片段长度多态性（ＲｅｓｔｒｉｃｔｉｏｎＦｒａｇｍｅｎｔＬｅｎｇｔｈＰｏｌｙｍｏｒｐｈｉｓｍ，ＲＦＬＰ）和ＰＣＲ－直接测序法（ＤｉｒｅｃｔＳｅｑｕｅｎｃｉｎｇ，ＤＳ）分析３８株结核分支杆菌耐ＳＭ分离株的ｒｐｓＬ基因。结果３８株耐ＳＭ分离株中，２５株ＳＳＣＰ异常、不被ＭｂｏⅡ消化、ＤＳ分析４３位密码子ＡＡＧ→ＡＧＧ突变；１株ＳＳＣＰ异常、可被ＭｂｏⅡ消化、ＤＳ分析３３位密码子ＧＴＡ→ＡＴＡ突变；１２株ＳＳＣＰ正常、可被ＭｂｏⅡ消化、ＤＳ分析未见异常；未发现８８位密码子突变。结论：大多数结核分支杆菌耐ＳＭ是由于其ｒｐｓＬ基因４３位密码子突变所致，采用ＰＣＲ－ＳＳＣＰ、ＰＣＲ－ＲＦＬＰ和ＰＣＲ－ＤＳ方法可快速测定部分结核分支杆菌ＳＭ耐药基因型。

Studies on the detection of rpsL gene mutations inM.tuberculosis by PCRdirect sequencing

Objective: To understand the mutations of streptomycinresistant genes in M.tuberculosis clinical isolates, and to develop a new molecular method for detecting drug resistance. Method: Analyzing the rpsL genes in 38 strains of M.tuberculosis streptomycinresistant isolates with PCRSSCP, PCRRFLP and PCRDS. Results M.tuberculosis strain H37Rv was used as a control. Of 38 streptomycinresistant isolates, 25 isolates displayed abnormal rpsL SSCP profiles, were not digested by MboII, and had AAGAGG mutations at codon 43; one displayed abnormal SSCP profile, was digested by MboII, and had GTAATA mutation at codon 33; 12 exhibited normal rpsL genes with PCRSSCP, PCRRFLP, PCRDS. There were no mutations found at codon 88. Conclusions: Resistance to streptomycin in most M.tuberculosis isolates is due to the mutations situated at codon 43 of genes encoding the ribosomal S12 protein (rpsL). PCRSSCP, PCRRFLP and PCRDS, ans it might become simple, rapid and reliable diagnostic tests for streptomycin resistance in some clinical isolates.