Khadka J B, Rai S K, Shrestha S, Maharjan B, Bhatta D R, Ghimire P
Central Department of Microbiology, Tribhuwan University, Nepal.
Nepal Med Coll J. 2011 Sep;13(3):147-51.
We studied the rifampicin (RIF) and isoniazid (INH) resistant genes in Mycobacterium tuberculosis isolated from sputum samples of re-treated TB cases using phenotypic drug susceptibility test (DST) and rapid molecular method (Genotype; MTBDR plus, Hains Life Science, Nehren, Germany). Of the total 207 isolates included in this study, 90 (42.0%) were RIF resistant, 107 (50.7%) were INH resistant whereas 86 (41.5%) were multidrug resistant (MDR) by DST. According to genotypic analysis, 37.0% (77/207) were RIF resistant, 50.2% (105/207) INH resistant and 70 (33.8%) were MDR. Among the total 90 RIF resistant isolates, 85.5% (77/90) showed mutation in 81 bp of rpoB gene and the mutation locus were distributed as follows; MUT1 Asp516Val (16.7%; 15/90), MUT2A His526Tyr (6.6%; 6/90), MUT2B His526Asp (5.5%; 5/90) and MUT3 Ser531Lue (56.7%; 51/90). Among the total 107 INH resistant isolates, the mutation located in katG gene was 98.1% (105/107) and in inhA MUT1 gene was (16.8%; 18/107). The mutation locus were distributed as follows; MUT1 Ser315Thr (77.6%; 83/107), MUT2 Ser315Ile (3.7%; 4/107) in katG and in inhA MUT1Cys15Thr (16.8%; 18/107). The highest frequency of mutations in rpoB gene was found at the region of codon Ser531Leu (56.7%) while the frequency of mutation in katG and inhA gene were found at the region of codon Ser315Thr (77.6%) and Cyst15Thr (17.1%), respectively. The rapid molecular test kit used in this study was found to be sensitive as well as specific for detection of RIF and INH resistant gene and also helpful in early detection of MDR-TB.
我们使用表型药敏试验（DST）和快速分子方法（Genotype；MTBDR plus，德国内伦海因斯生命科学公司），对从复治结核病患者痰标本中分离出的结核分枝杆菌中的利福平（RIF）和异烟肼（INH）耐药基因进行了研究。在本研究纳入的207株分离株中，通过DST检测，90株（42.0%）对RIF耐药，107株（50.7%）对INH耐药，而86株（41.5%）为多重耐药（MDR）。根据基因分型分析，37.0%（77/207）对RIF耐药，50.2%（105/207）对INH耐药，70株（33.8%）为MDR。在90株RIF耐药分离株中，85.5%（77/90）的rpoB基因81bp处发生突变，突变位点分布如下：MUT1 Asp516Val（16.7%；15/90）、MUT2A His526Tyr（6.6%；6/90）、MUT2B His526Asp（5.5%；5/90）和MUT3 Ser531Lue（56.7%；51/90）。在107株INH耐药分离株中，katG基因的突变率为98.1%（105/107），inhA MUT1基因的突变率为（16.8%；18/107）。突变位点分布如下：katG基因中的MUT1 Ser315Thr（77.6%；83/107）、MUT2 Ser315Ile（3.7%；4/107），inhA MUT1基因中的Cys15Thr（16.8%；18/107）。rpoB基因的最高突变频率出现在密码子Ser531Leu区域（56.7%），而katG和inhA基因的突变频率分别出现在密码子Ser315Thr区域（77.6%）和Cyst15Thr区域（17.1%）。本研究中使用的快速分子检测试剂盒被发现对检测RIF和INH耐药基因既敏感又特异，也有助于早期检测耐多药结核病。
