应用反向斑点杂交法检测耐利福平结核分支杆菌rpoB基因突变

目的　探讨快速检测rpoB基因突变的敏感方法 ,以期建立适合我国国情的结核分支杆菌耐药株的快速检测手段。方法　根据结核分支杆菌野生株序列 ,自行设计覆盖rpoB基因核心突变区的系列寡核苷酸探针并将其固定在尼龙膜上 ,然后应用生物素标记的特异性引物扩增包含核心突变区的rpoB基因片段 ,与固定在膜上的寡核苷酸探针杂交 ,对突变位点进行快速检测 ,并与药敏试验及DNA测序结果进行比较。结果　应用反向斑点杂交法检测 36株耐药株和 2 2株敏感株rpoB基因的突变位点 ,并据此判断其对利福平的药敏特性 ,结果敏感性为 88.9% ,特异性为 86 .4 % ,药敏结果符合率为 87.9% ,与测序结果的符合率为 89.7%。结论　反向斑点杂交法可以快速、敏感地检测rpoB基因突变 ,进而早期判断结核分支杆菌对利福平的药敏特性。     

中国耐利福平结核分支杆菌rpoB基因突变特点

目的 为了阐明中国结核分支杆菌耐利福平析rpoB基因突变特点。方法 对242株结核分支杆菌临床分离包括rpoB基因核心区域81个碱基在内的588个碱基进行序列测定,其中耐利福平株193株,利福平敏感株46株,人工诱导的耐利福平株3株。结果 89．1％（172．193）的临床分离耐药株存在rpoB基因突变,而46株敏感株无突变。531位氨基酸突变率为46．1％;526位氨基酸突变率为17．1％;联合突变发生率为12．4％;还有4株细菌发生同义突变;未检测到发生缺失或插入突变的菌株。高耐药组（耐250μg/ml利福平）531位氨基酸的突变率显著高于低耐药组（耐50μg/ml利福平）,P＜0．05。结论 中国结核分支杆菌耐利福平株的rpoB基因突变的发生率约为90％,其中最常见的突变位点是531位丝氨酸和526位组氨酸,两者突变率之和约为63％;利福平高耐药组531位氨基酸发生突变的几率高于低耐药组;受度蓖株未发现搬运入或缺失突变;DNA序列分析对临床用药有指导意义。     

DNA序列分析与PCR-SSCP分析结核分支杆菌利福平敏感性的比较

目的　了解DNA序列分析与PCR-SSCP法分析利福平敏感性的价值。方法 应用DNA序列分析与PCR-SSCP法检测利福平敏感的结核分支杆菌临床分离株 25株、耐药株 41株的利福平耐药相关基因rpoB基因核心区域的突变情况。 结果 25株利福平敏感株DNA序列分析未检测到rpoB基因突变,41株耐利福平株中 38株发生突变,突变率为 92.7% (38/41);25株利福平敏感的结核分支杆菌菌株PCR-SSCP带型与对照H₃₇R_v株相同,41株耐利福平结核分支杆菌菌株中38株SSCP带型不同于对照株,提示有突变存在。与DNA序列分析相比,PCR-SSCP检测准确率为 93.9% (62/66),敏感度为 92.1% (35/38);特异度是 96.4% (27/28)。结论 DNA序列分析对判断结核分支杆菌耐利福平非常有价值;PCR-SSCP可用于利福平耐药结核分支杆菌的初步筛选。     

逆向点杂交方法检测耐利福平结核分支杆菌rpoB基因突变

目的 建立一种灵敏、特异、快速检测结核分支杆菌耐药相关基因突变的方法，用于临床对利福平耐药的快速诊断。方法 将14条特异性探针固定在尼龙膜上，通过在下游引物标记生物素的方法得到生物素标记的结核分支杆菌DNA PCR扩增产物，与固定在尼龙膜上的特异性探针杂交，杂交物通过链酶亲和素标记辣根过氧化物酶及底物（四甲基联苯胺）显色判定结果。将杂交结果与基因测序结果及药敏试验结果进行对比分析。结果 采用逆向点杂交法共检测23株耐利福平及11株敏感型菌株，与药敏试验结果、测序结果符合率分别为28／34和30／34。所发现突变类型依次为：第531位突变11株，第526位突变7株，第533位突变3株。未检测到第516位、第513位碱基突变。结论 该方法可用于临床结核分支杆菌对利福平耐药性的快速检测。     

Characterization of rpoB mutations in rifampicin-resistant Mycobacterium tuberculosis isolated in China

The objective of this study was for the elucidation of the characteristics of the rpoB gene mutation in rifampicin (RIF)-resistant Mycobacterium tuberculosis strains isolated in China. The rifampicin resistance determination regions (RRDR) of the rpoB genes of 242 M. tuberculosis strains were sequenced, including 193 RIF-resistant, 46 RIF-sensitive clinical isolates and three manually induced RIF-resistant tuberculosis strains. Mutations in the 81 bp RRDR of the rpoB gene were identified in 89.6% (173/193) of RIF-resistant clinical isolates. No mutation was observed in RIF-sensitive strains. Ser531Leu mutations accounted for 46.1% (89/193) of RIF-resistant strains; the mutation frequency of 526-His was 17.6% (34/193) in RIF-resistant strains. Furthermore, a combination of 2-3 single-point mutations was observed in 24 RIF-resistant strains (12.4%; 24/193). Mutations in three manually induced RIF-resistant tuberculosis strains were located at codons 531 and 526, respectively. The results indicate that about 90% of rifampicin-resistant M. tuberculosis strains isolated in China had rpoB mutations;531-Ser and 526-His were the most common positions substituted; high-level rifampicin-resistant strains had a higher frequency of 531-Ser mutations than low-level rifampicin-resistant strains. Sequencing analysis of the 81 bp fragment in the rpoB gene is useful in predicting the rifampicin-resistant phenotype.     

应用基因阵列法快速检测结核分枝杆菌rpoB基因突变

目的　研制一种新型的基因阵列 ,用于结核分枝杆菌耐利福平分离株rpoB基因突变的快速检测。方法　根据结核分枝杆菌rpoB基因序列设计寡核苷酸探针并制作基因阵列 ,用生物素标记的引物扩增结核分枝杆菌rpoB基因突变热点的目的片断 ,与基因阵列杂交 ,同时以聚合酶链反应 单链构象多态性 (PCR SSCP)技术及DNA测序法为对照。结果　 111株结核分枝杆菌临床分离株经PCR SSCP分析 ,4 1株RFP敏感株SSCP图谱与结核分枝杆菌标准株相同 ;70株耐RFP菌株中 ,6 3株(90 % )SSCP图谱与结核分枝杆菌标准株不同 ,其余 7株SSCP图谱与结核分枝杆菌标准株相同。基因阵列检测结果 4 1株RFP敏感株杂交图谱与标准株完全相同 ,70株耐RFP临床分离株中 ,6 3株检测到rpoB基因突变 ,检出率为 90 % ;其中 37株 (5 3% ) 5 31位丝氨酸 (Ser)置换 ,15株 (2 1% ) 5 2 6位组氨酸(His)置换 ,11株 (16 % )其他位置的氨基酸置换。基因阵列检测结果与PCR SSCP及测序结果一致。结论　用基因阵列法可简便、快速、准确地检测出大多数结核分枝杆菌耐利福平分离株的rpoB基因突变。     

Prevalence of katG Ser315 substitution and rpoB mutations in isoniazid-resistant Mycobacterium tuberculosis isolates from Brazil.

SETTING: Four hundred and sixty-eight isoniazid (INH) resistant Mycobacterium tuberculosis isolates recovered from a selected Brazilian population. OBJECTIVE: To check for susceptibility to other chemotherapeutic drugs used in TB treatment, and to ascertain mutations involved in INH and rifampicin (RMP) resistance. DESIGN: Antimicrobial susceptibility to RMP, streptomycin and ethambutol (EMB) was evaluated by the resistance ratio method and pyrazinamide (PZA) by activity assay. Single strand conformation polymorphism (SSCP) and sequence analysis were performed in samples from this panel to confirm mutations in codon 315 of the katG and in a 69-bp region of the rpoB gene. RESULTS: Combined resistance to INH+RMP, INH+ PZA, INH+EMB, and INH+RMP+PZA was shown in respectively 272 (58.1%), 126 (26.9%), 47 (10%), 116 (24.8%) isolates. No katG mutation was found in 19 (39.6%) of 48 strains tested. Ser315Thr substitution was found in 29 (60.4%). All RMP-resistant strains tested (n = 25) showed rpoB mutations. S531L substitution was found in 15 (60%). CONCLUSION: INH-resistant strains isolated from selected Brazilian populations frequently show resistance to other first-line anti-tuberculosis drugs. rpoB mutation was responsible for RMP resistance in all strains. Among INHr strains, katG mutations were shown in only 60.4%. Genetic approaches targeting the rpoB gene but not the katG gene have a high sensitivity to detect resistance among Brazilian M. tuberculosis strains.     

Detection of rpoB mutations in rifampicin-resistant Mycobacterium kansasii

PURPOSE: To detect rifampicin-resistant mutations in Mycobacterium kansasii (M. kansasii). METHODS: We examined the M. kansasii isolates from sputum of patients at National Hospital Organization Kinki-chuo Chest Medical Center from January 1, 2001 to November 30, 2005 using drug-susceptibility testing, and analyzed 69-bp fragment of rpoB gene in rifampicin-resistant strains. RESULTS: Three strains from 314 isolates were determined as rifampicin resistant using drug-susceptibility testing. Those strains showed a rise in minimum inhibitory concentration (MIC), and had the mutations in rpoB gene. These point mutations in codons 513 and 516 were common mutations found in rifampicin-resistant clinical isolates of M. tuberculosis. DISCUSSION: We verified the association between rpoB gene mutations and rifampicin resistance in M. kansasii.     

序列分析重庆地区耐利福平结核分支杆菌的rpoB基因突变

目的　研究重庆地区结核分支杆菌对利福平 (R)的耐受与rpoB基因突变的关系。方法　PCR扩增 6 7株分离自重庆地区肺结核患者的耐R结核分支杆菌的rpoB基因片段 (319bp) ;测定扩增片段的序列 ,并与野型株序列作对比分析。 结果　 6 7株临床分离的耐R株中 ,8株 (12 % )无变异 ,5 9株 (88% )有突变 ,突变涉及 8个氨基酸位点。突变有 14种类型 ,4 9株(83% )的突变为单个密码子取代 ,9株为双密码子取代 ,1株为 3个碱基 (一个密码子 )插入 ,未检出碱基缺失。突变高发位点为 5 31位 (37/ 5 9)密码子 ,其次为 5 16位 (13/ 5 9)和 5 2 6位 (7/ 5 9)。 3株菌在 4 77位的谷氨酸 (Glu) ,天冬氨酸 (Asp)突变为首次发现。结论　重庆地区结核分支杆菌耐利福平的发生与rpoB基因的突变密切相关 ,突变的类型与国外的报告基本相似。PCR扩增和产物测序将是临床检测结核分支杆菌耐利福平和耐多药的一种迅速、准确的方法     

应用线性探针分析快速检测耐利福平结核分支杆菌的rpoB基因突变

目的：检测上海地区耐利福平结核分支杆菌的rpoB基因突变,评估线性探针分析（LiPA)法快速检测突变位点的意义。方法：对58株结核分支杆菌rpoB基因片段进行PCR扩增及DNA测序,从中选取18株耐药株和10株敏感株并应用LiPA法检测其突变位点,结果：LiPA法准确地检测出18株耐药株中17株的rpoB基因突变,10株敏感株均无突变;LiPA法检测耐药菌的敏感性为94．4％,与药敏结果的符合率为96．4％,结论：LiPA法可用于耐利福平结核分支杆菌rpoB基因的快速检测,而且具有较高的敏感性。     

Nitrate reduction as a marker for hypoxic shiftdown of Mycobacterium tuberculosis.

SETTING: In vitro cultures. OBJECTIVE: To characterize nitrate reduction during aerobic growth and hypoxic shiftdown to non-replicating persistence of Mycobacterium tuberculosis cultures. DESIGN: The rates of reduction of nitrate to nitrite were measured in cultures of M. tuberculosis growing aerobically or undergoing hypoxic shiftdown. RESULTS: Tubercle bacilli growing aerobically in the presence of nitrate reduce nitrate at a rate proportional to the substrate concentration, continuing until the substrate is exhausted. When the bacilli in an oxygen restricted model enter microaerophilic non-replicating persistence (NRP) stage 1, they exhibit a marked increase in rate of nitrate reduction that is independent of substrate concentration, and terminates by feedback inhibition when the concentration of nitrite produced approaches 2.5 mM. When bacilli in the oxygen restricted model are not supplemented with nitrate until they enter microaerophilic NRP stage 1, they exhibit an induction period before the rapid nitrate reduction starts. When the nitrate is not added until the bacilli have entered the anaerobic NRP stage 2, reduction of the substrate starts immediately. Nitrite is not reduced by M. tuberculosis in any stage of its growth or NRP. CONCLUSION: The hypoxically induced nitrate reduction probably serves a respiratory function in supporting hypoxic shiftdown of M. tuberculosis from aerobic growth to non-replication persistence and represents a useful new marker for monitoring that shiftdown. This response may help the bacilli survive in oxygen depleted regions of inflammatory or necrotic tissue, where nitrate can occur as a degradation product of nitric oxide.     

结核分枝杆菌rpoB基因突变特征的初步探讨

目的 了解浙江省耐利福平结核分枝杆菌rpoB基因突变特征.方法 对65株临床分离菌株rpoB基因509-631位点分别进行PCR-SSCP检测和DNA序列测定,观察不同耐药株rpoB基因突变的规律.结果 耐利福平分离株96.4%（27/28）存在rpoB基因突变,其中526位突变率64.3%（18/28）,513位突变率21.4%（6/28）,531位突变率7.1%（2/28）,529位突变率3.6%（1/28）;耐其他抗结核药18.5%（5/27）存在rpoB基因突变,突变位点具有随机性.所有敏感菌株均无突变.结论 rpoB基因突变与利福平耐药密切相关,浙江省rpoB基因突变主要以526位突变为主,其次为513位,两者占总数的86%（24/28）,而耐其他抗结核药菌株也存在rpoB基因的突变,但没有明显规律,且均对利福平敏感.     

结核分枝杆菌rpoB基因突变特征的初步探讨

目的了解浙江省耐利福平结核分枝杆菌rpoB基因突变特征。方法对65株临床分离菌株rpoB基因509-631位点分别进行PCR-SSCP检测和DNA序列测定,观察不同耐药株rpoB基因突变的规律。结果耐利福平分离株96.4%(27/28)存在rpoB基因突变,其中526位突变率64.3%(18/28),513位突变率21.4%(6/28),531位突变率7.1%(2/28),529位突变率3.6%(1/28);耐其他抗结核药18.5%(5/27)存在rpoB基因突变,突变位点具有随机性。所有敏感菌株均无突变。结论rpoB基因突变与利福平耐药密切相关,浙江省rpoB基因突变主要以526位突变为主,其次为513位,两者占总数的86%(24/28),而耐其他抗结核药菌株也存在rpoB基因的突变,但没有明显规律,且均对利福平敏感。     

rpoB,katG and inhA mutations in multi-drug resistant strains of Mycobacterium tuberculosis clinical isolates from southeast Mexico

Introduction

Previous knowledge of molecular mechanisms related with multi-drug resistances in tuberculosis is important if molecular diagnostic procedures want to be used in specific geographical regions. For that reason, the aim of this study was to investigate the mutations at rpoB, katG and inhA in multi-drug resistant tuberculosis isolates from Southeast Mexico.

变性高效液相色谱法检测结核分枝杆菌利福平耐药基因突变的初步探索

目的 探讨变性高效液相色谱(DHPLC)技术在MTB的利福平耐药菌株rpoB基因突变检测中的应用价值.方法 PCR扩增MTB的rpoB基因利福平耐药决定区,扩增产物与野生型DNA链形成异源双链,在65.4℃柱温下进行DHPLC分析.对DHPLC不同峰型菌株的rpoB基因片段进行测序,评价DHPLC技术的敏感度和特异度.结果 共分析46株MTB菌株,其中42株对利福平耐药,4株对利福平敏感.经DHPLC分析,产生15种不同图谱.测序结果表明,各图谱菌株突变特征不同.除D108和D24菌株的DHPLC峰形相同而突变特征不同外,其他菌株均为DHPLC峰型与基因多态性相一致,即DHPLC峰型相同则基因多态性相同,DHPLC峰型不同则基因多态性不同.结论 DHPLC具有简便快捷、高通量和自动化的特点,敏感度和特异度高,可用于快速检测耐药MTB的基因突变.