Background China is one of the high burden countries of Mycobacterium tuberculosis （TB） infection globally, with high incidence and mortality. We studied the molecular characteristics of rifampin （RIF） and isoniazid （INH） resistant Mycobacterium tuberculosis strains from Beijing, China, in order to find out the genetic marker for rapid detection of specific drug resistance.Methods Forty pansusceptible and 81 resistant strains of Mycobacterium tuberculosis isolated from Beijing, China during 2002-2005 were analyzed. The modified rifampin oligonucleotide （RIFO） assay based on reverse line blot hybridization was used to detect mutations in the 81 bp hot-spot region of rpoB gene, which is associated with RIF resistance. The INH resistance associated genes, regulatory region mab-inhA （-15C/T） and structural gene katG S315T were detected by reverse line blot hybridization and PCR-restriction fragment length polymorphism （RFLP） method respectively. All the strains were typed by spoligotying and the Beijing genotype was further subdivided by NTF locus analysis. The distribution of drug resistance associated mutations in the above genes was compared in these groups. Results Sixty-five （91.5%） of 71 RIF resistant and 52 （92.9%） of 56 multidrug-resistant （MDR, i.e. resistant to at least RIF and INH） strains were found to harbor mutations in the rpoB hot-spot region. No mutation was detected in RIF sensitive strains. The specificity and sensitivity of the modified RIFO assay were 100% and 91.5%, respectively, katG315 AGC〉ACC and inhA-15C〉T mutations were found in 40 （60.6%） and 10 （15.2%） of 66 INH resistant strains, respectively; 7.6% of INH-resistant strains had mutations in both of these genes. Therefore, a combined use of both katG315 and inhA-15 identified 68.2% of INH-resistant strains. The Beijing genotype accounted for 91.7% of total strains and was further subdivided into ＂modern＂ （76.6%） and ＂ancestral＂ （23.4%） group. There is no significant difference
探讨反向线性杂交技术(reverse line blot assay,RLB)在结核分枝杆菌利福平(RFP)耐药性快速检测中的应用价值。采用RLB将包含rpoB基因核心区的扩增产物与标记特异性探针的膜进行杂交,共对121株结核分枝杆菌进行RFP耐药性检测,并将结果与常规药敏实验进行比较。结果发现,121株中有71株对RFP耐药,56株为多重耐药株;采用RLB共检测到65株RFP耐药株rpoB基因核心区存在突变,其灵敏度为91.5%(65/71);50株RFP敏感株中均未检测到突变,则特异性为100%(51/51);56株多耐药菌株中,92.9%(52/56)存在rpoB基因核心区突变。因此,用RLB检测结核分枝杆菌RFP耐药株具有快速,高效,特异性和灵敏度高的优点,且可用于多耐药菌株的筛选,具有推广和潜在的临床应用价值。
