吉林省耐多药结核分枝杆菌rpoB及katG基因突变特征分析

目的分析吉林省耐多药结核分枝杆菌临床分离株rpoB、katG基因突变特点,为建立本省快速耐多药检测方法提供参考。方法对吉林省耐多药结核分枝杆菌菌株扩增rpoB、katG基因测序后比对分析。结果耐多药结核分枝杆菌rpoB、katG基因的突变率分别为83.53%和70.6%,突变类型包括点突变、联合突变和缺失。在rpoB基因中,82.30%突变发生在RRDR区域,最常见突变位点为rpoB 531、rpoB 526、rpoB 516。KatG基因突变率为70.6%,最常见突变位点为katG315,占所有突变的68.55%。结论吉林省耐多药结核分枝杆菌最常见突变位点为rpoB531、rpoB 526、rpoB 516和katG 315。     

艾滋病合并结核病患者结核分枝杆菌耐药基因突变特征分析

目的了解云南省艾滋病合并结核病患者中结核分枝杆菌(MTB)耐利福平RNA聚合酶β亚单位编码基因(rpoB)和耐异烟肼过氧化氢酶-过氧化物酶编码基因(katG)、烯酰基还原酶编码基因(inhA)突变特点。方法采用基因芯片技术,对该省208例艾滋病合并结核病患者标本进行MTB利福平耐药相关基因rpoB和异烟肼耐药相关基因katG、inhA分析。结果 208例标本中共34例(16.3%)耐药,其中单耐利福平6例(2.9%),单耐异烟肼10例(4.8%),二者同时耐药18例(8.7%)。24例利福平耐药MTB的rpoB基因突变位点主要为531(TCG→TTG),占66.7%(16/24);28例异烟肼耐药MTB的基因突变位点主要为katG基因315(AGC→ACC),占78.6%(22/28)。结论云南省艾滋病合并结核病患者中MTB利福平和异烟肼耐药基因突变具有多态性,其中耐利福平rpoB基因的主要突变位点为531(TCG→TTG),耐异烟肼katG、inhA基因的主要突变位点为katG基因315(AGC→ACC)。     

耐药结核分枝杆菌基因突变分析

目的 探讨结核分枝杆菌耐药表型与基因突变位点之间的相互关系.方法 采用序列特异性引物分别扩增92株结核分枝杆菌利福平耐药基因rpoB,异烟肼耐药基因katG、inhA、ahpC,链霉素耐药基因rrs、rpsL,乙胺丁醇耐药基因embB及喹诺酮耐药基因gyrA,SSCP筛选出突变序列,DNA测序分析突变性质.结果 59株利福平耐药株rpoB基因突变检出率94.9%(56/59),以Ser450Trp突变最多;90株异烟肼耐药株中,katG基因突变检出率38.9%(35/90),以Ser315Thr最多,3株检出inhA基因突变,ahpC基因无突变检出;34株喹诺酮耐药株中gyrA基因突变检出率82.4%(28/34),主要为Asp94Gly,其次为Ala90Val;31株链霉素耐药株中,15株检出rrs突变,最常见为A514C和A1041G,10株发生rpsL Lys88Arg突变,总的链霉素基因突变检出率为77.4%(24/31);31株乙胺丁醇耐药株中embB 基因突变检出率19.4%(6/31),主要为Met306Val.结论 耐药结核分枝杆菌耐药情况较为严重,以DNA测序为基础的基因突变分析能快速有效地检测结核分枝杆菌的rpoB、katG、gyrA、rrs、rpsL、embB 等耐药分子标识,显示了西安地区耐药性结核分枝杆菌的突变特点,为结核病的临床诊断和合理用药提供了实验依据.     

基因芯片法用于检测长沙地区结核分枝杆菌耐药性研究

目的了解长沙市中心医院2013年1月1日至2014年9月30日临床分离的1 031株结核分枝杆菌对利福平和异烟肼的耐药性。方法将结核分枝杆菌培养阳性,并经鉴定为结核分枝杆菌的1 031株菌株,采用绝对浓度法进行常规药敏检测,同时应用基因芯片技术检测利福平和异烟肼耐药相关的rpoB、katG和inhA基因上的位点突变,并对2种结果进行比较。结果基因芯片法检测利福平耐药性中,其敏感株896株,耐药株135株;检测异烟肼耐药性为敏感株901株,耐药株130株。与绝对浓度法比较,基因芯片检测利福平耐药结果与其一致的菌株共1 011株(包含敏感株894株,耐药株117株),符合率为98.00%;基因芯片检测异烟肼耐药结果与其一致的菌株共1 005株(包含敏感株890株,耐药株115株),符合率为97.48%。与利福平耐药相关的rpoB基因的突变位点最常见的为531TCG→TTG突变,占耐药株的51.11%;其次为526CAC→TAC突变耐药株的10.37%;526CAC→GAC共11株菌株突变,占耐药菌株的8.15%。异烟肼耐药主要是由katG315AGC→ACC位突变引起,占耐药株的83.85%,inhA-15C→T突变仅占12.30%。结论基因芯片法与绝对浓度法结果高度一致,可成为筛查利福平和异烟肼耐药性的快速有效方法,长沙地区结核分枝杆菌利福平和异烟肼耐药以rpoB531,526及katG315突变位点为主。     

应用多重PCR-单链构象多态性分析同时检测耐异烟肼和利福平的结核分枝杆菌

目的 探讨应用多重PCR-单链构象多态性分析(multiplexpulymerase chain reaction-single strand conformation polymorphism,multi-PCR-SSCP)方法快速、特异地同时快速检测结核分枝杆菌对异烟肼和利福平耐药性的效能.方法 根据结核分枝杆菌的inhA序列、katG序列、rpoB序列,分别设计出3对特异性寡聚核苷酸引物.采用multi-PCR-SSCP技术,一次性检出耐异烟肼和利福平的结核分枝杆菌.新方法的有效性通过116株临床分离株(70株耐异烟肼,66株耐利福平)的验证.结果 名 Multi-PCR-SSCP方法检测临床分离株基因突变的有效性,以细菌培养和药敏试验结果为金标准.116株临床分离株和H37Rv标准株中除了4株katG缺失突变,其余菌株3个基因katG、inhA和rpoB在单基因PCR中都扩增成功.与H37Rv标准株相比,46株katG基因突变,14株inhA基因突变,58株rpoB基因突变.38株katG和rpoB,4株inhA和rpoB,4株inhA和katG同时突变,还有2株3个基因都有突变.multi-PCR-SSCP对于耐异烟肼和利福平的结核分枝杆菌检出的敏感度分别为80%、82%,特异度分别为100%和92%.结论 multi-PCR-SSCP方法敏感、特异,能同时快速有效地检测耐多药结核分枝杆菌,有望成为临床指导用药的好方法,为深入研究耐药基凶检测奠定了良好的基础.     

结核分枝杆菌对利福平和异烟肼耐药基因突变快速检测方法的建立

目的建立结核分枝杆菌对利福平和异烟肼耐药基因突变的快速检测方法。方法根据结核分枝杆菌标准株H37Rv序列，自行设计覆盖rpoB、katG、inhA基因突变区的系列寡核苷酸探针，并检测临床样品中结核分枝杆菌的基因突变情况，以此来判断耐药结果。结果在56个利福平耐药菌株中，有50个菌株都在rpoB基因上榆出有突变，利福平耐药突变检出率为89．3％（50／56）；有30个利福平敏感菌株rpoB基因上都未检出突变。有58个异烟肼培养的耐药菌株中有47个在katG或inhA基因上检出有突变，异烟肼耐药突变检出率为81．0％（47／58）；有30个异烟肼敏感菌株katG或inhA基因上未检出突变。结论用膜芯片检测结核分枝杆菌对利福平和异烟肼的耐药性，具有较高的特异性和敏感性，可用于临床结核分枝杆菌耐药性的检测。     

结核分枝杆菌耐利福平和异烟肼相关基因快速检测的应用研究

目的 利用DNA芯片检测技术直接检测痰标本中结核分枝杆菌耐利福平(RFP)、异烟肼(INH)相关的耐药基因(rpoB、katG/inhA),评价DNA芯片检测技术临床应用的可行性.方法 对586份涂阳痰标本使用L-J培养并用终点法确定其耐药性,同时利用DNA芯片检测技术检测痰标觋本中结核分枝杆菌的rpoB、katG/inhA常见基因突变位点的突变情况,比对两种方法的检测结果,对不符合的菌株测定其相应DNA序列,评估上述试验的准确性.结果 (1)586份涂阳痰标本,其中3(+)163份、2(+)204份、1(+)217份,培养阳性584份.耐药结果显示,对INH、RFP敏感的菌株分别为361株和327株,耐药菌株分别为223株和247株,其中低浓度耐药、高浓度敏感菌株分别为93株和59株,低浓度、高浓度均耐药菌株分别为130株和188株.(2)耐药基因特异性片段扩增阳性标本367份(62.8%)、阴性217份(37.2%).对INH耐药相关基因(katG/inhA)突变检出率是28.4%,突发发生位点集中在katG315位密码子(89.8%);对RFP耐药相关基因(rpoB)突变检出率是55.9%(137/247),突变发生位点主要在rpoB 531和rpoB 526位密码子,发生率分别是68.6%和16.1%.(3)对L-J药敏结果与DNA芯片检测结果不符的菌株进行DNA序列分析,发现有漏检现象.结论 DNA芯片技术直接检测样本中结核分枝杆菌的相关耐药基因存在可行性,如直接应用于临床样本检测,关键要解决样本中DNA的提取效率、PCR的扩增效率和试验的质量控制.     

合肥地区耐多药结核分枝杆菌异烟肼、链霉素及 乙胺丁醇耐药相关基因位点表达研究

目的研究耐多药结核分枝杆菌异烟肼(INH)、链霉素(SM)及乙胺丁醇(EMB)耐药相关基因位点的表达情况。方法选取该院2013年1月至2017年12月临床分离的101株耐多药结核分枝杆菌,利用测序法和基因芯片法分别检测INH、SM和EMB耐药相关基因及突变位点。结果 101株耐多药结核分枝杆菌中对SM耐药率69.3%;对EMB耐药率51.4%;对SM和EMB二者均耐药的耐药率44.5%。基因芯片法检出95例INH耐药相关基因突变,其中katG基因315M位点突变率为77.8%;inhA基因-15M位点突变率为89.4%。检出64例rpsL SM耐药相关基因,其中43M位点突变率为89.0%;88M位点突变率为11.0%。检出47例embB EMB耐药相关基因,以306M2位点突变为主,突变率为68.0%。测序法检出98例INH耐药相关基因突变,katG基因突变以315位点为主突变率为73.4%;inhA基因突变以-15位点为主突变率为87.7%;oxyR-ahpC基因-12和-10位点突变率分别为10.2%和8.2%。检出68例SM耐药相关基因突变,rpsL基因以43位点为主突变率为86.8%;rrs基因512、513、516位点突变率分别为5.9%、8.8%、8.8%。检出50例EMB耐药相关基因embB以306位点为主突变率为88.0%。结论耐多药结核分枝杆菌INH、SM及EMB耐药基因位点表达可作为结核分枝杆菌临床检测耐药性的有效依据,为提高耐多药结核分枝杆菌耐药性检测的敏感度,应将INH耐药相关oxyR-ahpC基因和SM耐药相关rrs基因纳入我国快速分子诊断产品中。     

等位基因特异性PCR法快速检测结核分枝杆菌常见耐药突变基因

摘要：目的：建立一套同步检测结核分枝杆菌(MTB)常见耐药突变基因的等位基因特异性PCR（AS-PCR）检测体系,以间接判断对利福平（RFP）与异烟肼（INH）的耐药性。 方法：用AS-PCR技术同步检测58株MTB临床分离株rpoB基因516位、526位和531位,katG基因315位及inhA基因-15位密码子突变,并与DNA测序结果进行比对。 结果：AS-PCR法对RFP耐药株检出率为95.1%（39/41）,其中rpoB基因531位、526位、516位点突变分别检出28株、10株、2株,包括531位与526位联合点突变1株;未检出突变的2株RFP耐药株经测序验证1株未发生突变、1株发生533位点突变;RFP敏感株均未检测到突变。AS-PCR法对INH耐药株检出率为86.5%（45/52）,其中katG基因315位点突变43株、inhA基因-15位点突变2株,未检出突变的7株INH耐药株经测序验证未见突变;INH敏感株均未检测到突变。 结论：等位基因特异性PCR能够快速检测MTB常见突变基因,具有较高的敏感性与特异性,快速经济、操作简便。     

肺结核与结核性脑膜炎病例中结核分枝杆菌耐利福平相关基因突变分布分析

目的分析结核性脑膜炎与肺结核病例中,导致结核分枝杆菌利福平耐药的rpoB基因突变分布规律及差异。方法对包含利福平耐药决定区81bp的102株结核分枝杆菌临床分离株的PCR产物进行测序分析。结果 102株利福平耐药的结核分枝杆菌的rpoB基因测序发现,63株导致肺结核的结核分枝杆菌的rpoB基因突变常见位点为:531(53.97%),526(20.63%),516(6.45%)。39株导致结核性脑脑膜炎的rpoB基因突变最常见位点为:531(61.54%),526(20.51%),533(7.69%)。结论导致结核性脑膜炎与导致肺结核的结核分枝杆菌耐利福平rpoB基因的最常见两个突变位点(531和526)无显著差异。其中531位密码子的Ser-Leu突变率占明显优势。     

Molecular Characterization of Multidrug-Resistant Mycobacterium tuberculosis Isolates from China

To investigate the molecular characterization of multidrug-resistant tuberculosis (MDR-TB) isolates from China and the association of specific mutations conferring drug resistance with strains of different genotypes, we performed spoligotyping and sequenced nine loci (katG, inhA, the oxyR-ahpC intergenic region, rpoB, tlyA, eis, rrs, gyrA, and gyrB) for 128 MDR-TB isolates. Our results showed that 108 isolates (84.4%) were Beijing family strains, 64 (59.3%) of which were identified as modern Beijing strains. Compared with the phenotypic data, the sensitivity and specificity of DNA sequencing were 89.1% and 100.0%, respectively, for isoniazid (INH) resistance, 93.8% and 100.0% for rifampin (RIF) resistance, 60.0% and 99.4% for capreomycin (CAP) resistance, 84.6% and 99.4% for kanamycin (KAN) resistance, and 90.0% and 100.0% for ofloxacin (OFX) resistance. The most prevalent mutations among the MDR-TB isolates were katG315, inhA15, rpoB531, -526, and -516, rrs1401, eis-10, and gyrA94, -90, and -91. Furthermore, there was no association between specific resistance-conferring mutations and the strain genotype. These findings will be helpful for the establishment of rapid molecular diagnostic methods to be implemented in China.     

Molecular Characterization of Multidrug-Resistant Isolates of Mycobacterium tuberculosis from Patients in North India

The World Health Organization has identified India as a major hot-spot region for Mycobacterium tuberculosis infection. We have characterized the sequences of the loci associated with multidrug resistance in 126 clinical isolates of M. tuberculosis from India to identify the respective mutations. The loci selected were rpoB (rifampin), katG and the ribosomal binding site of inhA (isoniazid), gyrA and gyrB (ofloxacin), and rpsL and rrs (streptomycin). We found known as well as novel mutations at these loci. Few of the mutations at the rpoB locus could be correlated with the drug resistance levels exhibited by the M. tuberculosis isolates and occurred with frequencies different from those reported earlier. Missense mutations at codons 526 to 531 seemed to be crucial in conferring a high degree of resistance to rifampin. We identified a common Arg463Leu substitution in the katG locus and certain novel insertions and deletions. Mutations were also mapped in the ribosomal binding site of the inhA gene. A Ser95Thr substitution in the gyrA locus was the most common mutation observed in ofloxacin-resistant isolates. A few isolates showed other mutations in this locus. Seven streptomycin-resistant isolates had a silent mutation at the lysine residue at position 121. While certain mutations are widely present, pointing to the magnitude of the polymorphisms at these loci, others are not common, suggesting diversity in the multidrug-resistant M. tuberculosis strains prevalent in this region. Our results additionally have implications for the development of methods for multidrug resistance detection and are also relevant in the shaping of future clinical treatment regimens and drug design strategies.     

焦磷酸测序技术检测结核分枝杆菌四种药物耐药性

目的 利用焦磷酸测序技术检测结核分枝杆菌对利福平、异烟肼、氧氟沙星、阿米卡星的耐药性,并对其临床应用进行评价.方法 收集上海市肺科医院2008-2009年临床确诊的肺结核患者的痰标本培养阳性结核分枝杆菌89株.所有菌株按<结核病诊断实验室检验规程>进行分枝杆菌培养、菌种鉴定.另外10株已知药敏结果的结核分枝杆菌来自上海市肺科医院菌株库.利用焦磷酸测序技术,以10株已知药敏结果和经直接测序已知耐药基因突变情况的结核分枝杆菌为试验菌株,探索焦磷酸测序检测结核分枝杆菌rpoB、katG、gyrA、rrs耐药基因的最佳模式,并用该条件检测89株结核分枝杆菌临床分离株,检测结果与Bactec 960药敏法进行比较.结果 rpoB、gyrA基因检测宜采用焦磷酸测序序列分析模式,katG、rrs基因检测宜采用焦磷酸测序单核苷酸多态性模式.以Bactec 960药敏法测定结果为判断标准,则焦磷酸测序法检测89株结核分枝杆菌临床分离株对利福平、异烟肼、氧氟沙星、阿米卡星耐药性的敏感度分别为98.0%、64.1%、79.5%、78.3%,特异度分别为97.5%、100.0%、90.0%、100.0%,准确性分别为97.8%、77.5%、85.4%、94.4%,该法检测利福平、氧氟沙星、阿米卡星的检测结果与Bactec 960药敏检测结果一致性较好,Kappa值均≥0.7.结论 焦磷酸测序技术检测结核分枝杆菌对利福平、异烟肼、氧氟沙星、阿米卡星耐药性具有快速、准确、高通量的优点,是一种可对结核分枝杆菌多种药物耐药性进行快速检测的方法.

Abstract：

Objective To develop an assay to determine Mycobacterium tuberculosis resistance to rifampin, isoniazid, ofloxacin and amikacin by pyrosequencing and evaluate the value of this method in clinical application. Methods Eighty-nine clinical isolates of Mycobacterium tuberculosis from tuberculosis patients were collected from Shanghai Pulmonary Hospital during 2008 to 2009. All strains were isolated from decontaminated sputum, cultured on Lowenstein-Jensen media and identified by traditional biochemical tests with standard methods. Ten Mycobacterium tuberculosis were selected from the strain bank of Shanghai Pulmonary Hospital. The optimal conditions of detection of rpoB, katG, gyrA and rrs gene by pyroseuencing were determined, using the 10 Mycobacterium tuberculosis strains whose drug susceptibility of Bactec 960 and sequence of rpoB, katG, gyrA, rrs gene were known. Then the drug susceptibility of 89 Mycobacterium tuberculosis clinical isolate strains were detected by pyrosequencing using this conditions and the results were compared with that of the Bactec 960 methods. Results The pyrosequencing program of sequence analysis was suitable for the detection of the mutations of rpoB and gyrA genes, and the program of single nucleotide polymorphism was suitable for katG and rrs genes. Among the 89 Mycobacterium tuberculosis clinical isolates,when using the drug susceptibility of Bactec 960 as the standard, the sensitivity of rifampin, isoniazid,ofloxacin and amikacin is 98.0%, 64. 1%, 79.5%, 78. 3% respectively, the specificity is 97.5%,100. 0%, 90. 0%, 100. 0% respectively, the accuracy is 97.8%, 77. 5%, 85.4%, 94. 4% respectively,tested by pyrosequencing. The results of the detection of resistance to rifampin, isoniazid, ofloxacin and amikacin in Mycobacterium tuberculosis using pyrosequencing technique were almost the same with that of Bactec 960, and Kappa ≥0. 7 in each detection. Conclusion Pyrosequencing is thus a rapid, accurate and high throughput method for detecting Mycobacterium tuberculosis resistance to these four drugs.     

Molecular characteristics of rifampicin- and isoniazid-resistant Mycobacterium tuberculosis isolates from the Russian Federation

OBJECTIVES: Three Mycobacterium tuberculosis genetic loci--rpoB and katG genes and the fabG1(mabA)-inhA operon promoter region--were studied to reveal the mutations associated with rifampicin and isoniazid resistance. METHODS: Four hundred and twelve isolates of M. tuberculosis from different regions of the Russian Federation were collected during 1997-2005. A matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS)-based minisequencing method was used for the detection of mutations. RESULTS: Thirteen different variants of single mutations in codons 533, 531, 526, 516, 513 and 511 of the rifampicin resistance-determining region of the rpoB gene as well as the TTG insertion in the 514a position were found among the rifampicin-resistant isolates. Single nucleotide substitutions in codons 531, 526 and 516 (64.8%, 10.3% and 7.7%, respectively) were the most prevalent mutations. Codon 526 was shown to be the most variable of all. No mutations were detected in rpoB genes for 29 (10.7%) of the rifampicin-resistant isolates. 76.9% of the isoniazid-resistant isolates carried single mutations in codon 315 of the katG gene. For another 12.9% of them, double mutations in the katG gene and the fabG1(mabA)-inhA promoter region were revealed. No mutations were detected in 8.2% of the isoniazid-resistant isolates. CONCLUSIONS: Molecular analysis of the loci of rpoB and katG genes and the inhA promoter region of 412 M. tuberculosis clinical isolates from various parts of the Russian Federation was carried out. The new MALDI-TOF MS-based method may be used for rapid and accurate monitoring of the spread of drug resistance.     

Phenotypic and genotypic characterization of drug-resistant Mycobacterium tuberculosis strains

Of 142 pulmonary tuberculosis patients, 76 were considered high risk for the development of resistance, and 24 were confirmed as resistant strain carriers. Resistant isoniazid strains presented a high frequency of katG and ahpC mutations (90%) correlated with an MIC >4 microg/mL (94%). inhA mutations were not seen. rpoB mutations were identified in 78.6% of rifampicin-resistant strains, usually in codon 531 (72.7%), and 75% had an MIC >16 microg/mL. katG and rpoB mutations recognized 88.2% of multidrug-resistant strains and proved more efficient than the katG and rpoB mutations alone. Seventy percent of resistant pyrazinamide strains had pncA mutations between genes 136 and 188, 62.5% of them with an MIC >900 microg/mL. Pyrazinamidase inactivity was not an efficient resistance marker because 60% of pncA-mutated strains maintained enzymatic activity despite displaying good correlation with high resistance levels. Resistant ethambutol strains had embB mutations in codon 306, with MIC >16 microg/mL.     

广西壮族自治区结核分枝杆菌异烟肼与利福平耐药基因联合突变特征分析

  目的   了解广西壮族自治区（广西）结核分枝杆菌异烟肼与利福平耐药基因联合突变特征，为耐多药结核病的分子诊断和治疗提供依据。  方法   2017—2018年从广西30个结核病防治定点机构收集的结核分枝杆菌中选取49株耐多药菌株和459株全敏感菌株进行全基因组测序。  结果   耐多药表型与基因联合突变的符合率为71.43%。 单基因突变率和基因联合突变率在耐多药菌株中均高于全敏感菌株（χ2=5.753，P=0.016; χ2=284.034，P<0.001）。 katG和rpoB的单基因突变率在耐多药菌株中高于全敏感菌株（χ2=7.524，P=0.006; χ2=4.353，P=0.037）。 katG＋rpoB基因联合突变在耐多药菌株中高于全敏感菌株（χ2=279.956，P<0.001）。 在基因联合突变的位点分布中，以katG315＋rpoB450和katG315＋rpoB445位点突变为主，占40.82%（20/49），2种形式的基因位点联合突变率在耐多药菌株中均高于全敏感菌株（χ2=144.232，P<0.001; χ2=19.014，P<0.001）。  结论   对异烟肼和利福平耐药基因联合突变的检测可作为广西耐多药筛查的重要指标。 广西结核分枝杆菌异烟肼和利福平耐药基因突变以katG315、rpoB450和rpoB445位点突变为主，基因联合突变以katG＋rpoB形式为主。 katG315＋rpoB450和katG315＋rpoB445位点突变是广西地区耐多药产生的主要分子机制。     

Genetic and phenotypic characterization of drug-resistant Mycobacterium tuberculosis isolates in Hong Kong

OBJECTIVES: To characterize 250 drug-resistant Mycobacterium tuberculosis (MTB) isolates in Hong Kong with respect to their drug susceptibility phenotypes to five common anti-tuberculosis drugs (ofloxacin, rifampicin, ethambutol, isoniazid and pyrazinamide) and the relationship between such phenotypes and the patterns of genetic mutations in the corresponding resistance genes (gyrA, rpoB, embB, katG, inhA, ahpC and pncA). METHODS: The MIC values of the aforementioned anti-tuberculosis drugs were determined for each of the 250 drug-resistant MTB clinical isolates by the absolute concentration method. Genetic mutations in the corresponding resistance genes in these MTB isolates were identified by PCR-single-stranded conformation polymorphism/multiplex PCR amplimer conformation analysis (SSCP/MPAC), followed by DNA sequencing of the purified PCR products. RESULTS: Resistance to four or five drugs was commonly observed in these MTB isolates; such phenotypes accounted for over 34% of the 250 isolates. The most frequently observed phenotypes were those involving both rifampicin and isoniazid, with or without additional resistance to the other drugs. A total of 102 novel mutations, which accounted for 80% of all mutation types detected in the 7 resistance genes, were recovered. Correlation between phenotypic and mutational data showed that genetic changes in the gyrA, rpoB and katG genes were more consistently associated with a significant resistance phenotype. Despite this, however, a considerable proportion of resistant MTB isolates were found to harbour no detectable mutations in the corresponding gene loci. CONCLUSIONS: These findings expand the spectrum of potential resistance-related mutations in MTB clinical isolates and help consolidate the framework for the development of molecular methods for delineating the drug susceptibility profiles of MTB isolates in clinical laboratories.     

结核分枝杆菌katG、inhA、ahpC等突变与异烟肼耐药关系的研究

目的：了解结核分枝杆菌katG、inhA、ahpC、fabG1、sodA及sodC基因突变的特征及其与耐异烟肼的关系。方法对127例活动性肺结核患者痰标本进行菌型鉴定及结核分枝杆菌药敏试验,提取结核分枝杆菌菌株DNA,应用PCR扩增katG、inhA及ahpC、fabG1、sodA及sodC基因片段,并进行DNA序列分析。结果结核分枝杆菌药物敏感试验显示127株结核分枝杆菌中,其中47株耐异烟肼,80株对异烟肼敏感,耐异烟肼率为37.01%。47株耐异烟肼中,29株存在katG和（或）inhA基因突变,其中22株（46.81%,22/47）存在katG基因单位点突变,3株（6.38%,3/47）存在inhA基因单位点突变,4株（8.51%,4/47）存在katG及inhA基因联合位点突变。22株katG基因单位点突变中,20株为AGC315ACC、AGC315AAC （42.55%,20/47）突变,2株（2.13%,1/47）分别为CTG378CCG（Leu378Pro）、ACG394ATG（Thr394Met）突变,该突变位点及突变形式尚未见文献报道。18株katG及inhA未突变结核分枝杆菌均未检测到ahpC、fabG1、sodA及sodC基因突变。结论结核分枝杆菌对异烟肼耐药主要与katG和inhA基因突变有关。耐异烟肼结核分枝杆菌临床分离株378和394新突变位点的发现为进一步研究耐药机制以及耐药结核病的快速检测提供了依据。