Comparison of microplate hybridization with gel electrophoresis and dot blot hybridization for the rapid detection of Mycobacterium tuberculosis PCR products

A microplate ELISA hybridization assay has been developed for the detection of the IS6110 PCR products of M. tuberculosis from sputum specimens. In this study, its efficacy was evaluated by comparison with agarose gel electrophoresis (AGE) and dot blot hybridization (DBH), with culture results as the 'gold standard'. The assay was used with 190 sputum samples: the PCR results detected by ELISA and AGE showed close agreement, with sensitivity, specificity and accuracy of 90%, 100% and 96% respectively. The same values for DBH were 92%, 98% and 96% respectively. The validities of these methods were not statistically significantly different (p>0.05). The agreement rates of PCR product detection by AGE comparing with DBH and ELISA were 0.964 and 0.964 respectively, while that of DBH and ELISA was 1.0 by Kappa analysis. The overall agreement was not statistically significantly different (p>0.05). Use of DBH or ELISA hybridization increased the sensitivity of detection by AGE 10-fold from 10 pg to 1 pg of purified DNA per reaction; ie from about 30 to about 3 organisms. The amount of PCR product detected by ELISA was only one half of that detected by the other methods; the total assay time of ELISA following the PCR was 4 hours. In conclusion, the microplate hybridization assay may replace AGE and DBH for the detection of the PCR products of M. tuberculosis because of its sensitivity, specificity and accuracy. Additional advantages of the microplate assay over AGE and DBH include rapidity, ease of use, greater safety, cost effectiveness and greater objectivity in the reading of results; the technique is suitable for use in epidemiological studies for the analysis of a large number of samples.     

巢式实时荧光定量聚合酶链反应检测结核分枝杆菌DNA的临床应用

目的探讨巢式实时荧光定量PCR（QNRT-PCR）检测结核分枝杆菌（MTB）DNA的临床价值。方法应用SYBR Green I建立检测结核分枝杆菌MTP64基因的QNRT—PCR方法,分别检测24份肺结核患者痰液,27份结核性胸膜炎患者胸水,以及对照组75份痰液和胸水的MTBDNA含量。结果以培养为金标准,QNRT—PCR敏感性、特异性、阳性预测值（PPV）、阴性预测值（NPV）分别为95．83％、61．54％、69．70％和94．12％,结核性胸膜炎的阳性率为70．37％。三种PCR方法阳性率比较,差异具有统计学意义（P〈0．05）,QNRT—PCR与实时荧光定量PCR拷贝数配对检验差异没有统计学意义（P〉0．05）,QNRT—PCR与实时荧光定量PCR的Cr值配对检验差异具有统计学意义（P〈0．01）。结论QNRT—PCR方法可检测痰液和胸水MTB DNA,对含微量MTB DNA样本的高敏感性在结核病的早期诊断中有重要参考价值。     

A comparison between the efficiency of the Xpert MTB/RIF assay and nested PCR in identifying Mycobacterium tuberculosis during routine clinical practice

Objectives

Polymerase chain reaction (PCR) for the detection of Mycobacterium tuberculosis (MTB) is more sensitive, specific, and rapid than the conventional methods of acid-fast bacilli (AFB) smear and culture. The aim of this study was to determine if the Xpert MTB/rifampicin (RIF) assay had additional advantages over nested PCR for the detection of MTB in a geographical area with intermediate tuberculosis (TB) incidence.

Methods

Between February and December 2013, the Xpert MTB/RIF assay and MTB nested PCR, as well as AFB smear and culture, were simultaneously performed on 198 clinical samples (160 pulmonary and 38 non-pulmonary specimens) collected from 171 patients hospitalized at Hallym University Medical Center for possible TB. The accuracy of the diagnosis of MTB culture-positive TB and the turnaround time of reporting laboratory results were calculated and compared. Rifampin resistance by the Xpert MTB/RIF assay was reviewed with that of conventional drug susceptibility testing (DST).

Results

The sensitivity, specificity, and positive and negative predictive values of the Xpert MTB/RIF assay and MTB nested PCR for diagnosis of MTB culture-positive pulmonary TB were 86.1% vs. 69.4% (P=0.1563), 97.8% vs. 94.1% (P=0.2173), 91.2% vs. 75.8% (P=0.1695), and 96.4% vs. 92.0% (P=0.2032), respectively. The median turnaround times of the Xpert MTB/RIF assay and MTB nested PCR were 0 [0-4] days and 4 [1-11] days, respectively (P<0.001). Two cases of rifampin resistance, as determined by the Xpert MTB/RIF assay, were found to be multi-drug resistant (MDR) pulmonary TB by DST.

Conclusions

The Xpert MTB/RIF assay seemed to be sensitive, specific, and comparable to nested PCR for identifying MTB among clinically suspected TB patients, and the assay can be valuable in giving a timely identification of resistance to rifampin.     

结核分枝杆菌/利福平耐药实时荧光定量核酸扩增检测技术诊断艾滋病患者肺结核的临床应用评价

目的:探讨结核分枝杆菌(Mycobacterium tuberculosis,MTB)/利福平耐药实时荧光定量核酸扩增检测(Xpert MTB/RIF)技术诊断艾滋病患者肺结核的应用价值。方法:回顾性分析2017年7月至2019年11月上海市(复旦大学附属)公共卫生临床中心收治的226例疑似肺结核的艾滋病患者的临床资料。分别进行痰涂片荧光染色显微镜下检查、BACTEC MGIT 960液体培养(或罗氏固体培养)和Xpert MTB/RIF检测,并分析在艾滋病患者中Xpert MTB/RIF技术诊断MTB感染和利福平耐药的灵敏度和特异度。结果:226例疑似肺结核患者中,痰培养阳性94例(41.6%),其中MTB阳性51例(54.3%),非结核分枝杆菌(nontuberculosis mycobacteria,NTM)阳性43例(45.7%)。以痰分枝杆菌培养阳性且结核分枝杆菌分泌蛋白64抗原阳性为金标准,Xpert MTB/RIF技术诊断MTB的灵敏度为72.6%[95%可信区间(confidence interval,CI)66.7%~78.4%],特异度为97.1%(95%CI 95.0%~99.3%)。Xpert MTB/RIF技术诊断痰涂片阳性患者MTB的灵敏度为76.7%(95%CI 67.7%~85.8%),特异度为90.0%(95%CI 83.6%~96.5%)。Xpert MTB/RIF技术诊断痰涂片阴性患者MTB的灵敏度为50.0%(95%CI 41.8%~58.2%),特异度为99.3%(95%CI 97.9%~100.0%)。18例患者同时检测利福平表型和基因型耐药,以表型耐药为金标准,Xpert MTB/RIF技术检测利福平基因型耐药的灵敏度为75.0%,特异度为100.0%。结论:艾滋病患者中Xpert MTB/RIF技术诊断肺结核的灵敏度和特异度均较高,且能快速区分MTB和NTM,具有较好的应用价值。     

Comparative evaluation of the isothermal and chimeric primer-initiated amplification of nucleic acids (ICAN) and Roche Amplicor PCR and culture for detecting Mycobacterium tuberculosis complex in sputum samples

We compared the ability of the newly developed ICAN MTB Detection Kit (TaKaRa Bio Inc.), which uses the Isothermal and Chimeric primer-initiated Amplification of Nucleic acid (ICAN), with that of COBAS Amplicor PCR System (Roche Diagnostics) to directly detect Mycobacterium tuberculosis complex (MTB) in sputum samples. A total of 142 sputum samples from 120 patients were examined in this study. The results were compared with those of acid-fast staining and MGIT liquid culture system (BD) following identification by the probe test (DDH Mycobacteria Kit). A total of 68 specimens were MGIT positive for MTB. In addition, 62 specimens were positive by the combination of staining and MGIT assay for MTB. When compared with that for MGIT, the sensitivity of each assay system was 88.2% for ICAN and 92.6% for COBAS Amplicor, respectively. The specificity of each assay system was 65.7% for ICAN and 62.7% for COBAS Amplicor, respectively. Coincidence between ICAN and COBAS Amplicor assay results was 96.3% (130 of 135 samples). No significant difference was observed between the results of the two assay methods. It is concluded that although both nucleic acid amplification methods are sensitive and specific for the detection of MTB in the respiratory specimens, ICAN system appeared to be more rapid (within 3.5 h from the specimen collection) than Amplicor system. The ICAN system will be useful in clinical laboratories for the rapid detection of MTB without specially programmed thermo-cycler.     

Effectiveness of the BDProbeTec ET system for detection of Mycobacterium tuberculosis complex in sputum and bronchoalveolar lavage specimens

ObjectiveThe diagnostic efficacy of the BDProbeTEC ET Mycobacterium tuberculosis (MTB) complex direct detection assay (DTB) performed on bronchoalveolar lavage (BAL) specimens and sputum smears was compared with acid-fast bacilli (AFB) smear microscopy.MethodAFB smear microscopy, DTB and culture results of 286 patients with pulmonary tuberculosis were retrospectively reviewed. A total of 120 patients provided expectorated sputum samples, and 166 patients provided BAL specimens. Culture results and clinical diagnosis were used as gold standards.ResultsThe sensitivity and specificity of the DTB assay in detecting MTB in sputum specimens was significantly higher compared to AFB smear microscopy (83.7% and 82.4%, vs. 75.6%, and 41.2%, respectively). The sensitivity and specificity of the DTB assay in detecting MTB in sputum samples was 77.2% and 100% compared to clinical diagnosis, while AFB smear had a sensitivity and specificity of 70.3% and 26.3%, respectively. Compared to culture, DTB had a sensitivity and specificity of 82.8% and 93.2%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 41.9% and 87.7%, respectively. Compared to clinical diagnosis, DTB had a sensitivity and specificity of 67.2% and 100%, respectively, in detecting MTB from BAL specimens; AFB smear had a sensitivity and specificity of 34.8% and 79.5%, respectively.ConclusionsThe superior performance of the DTB assay relative to AFB smear microscopy makes it a valuable tool to enable early diagnosis of MTB, thereby improving patient care and reducing transmission.     

荧光PCR熔解曲线法检测结核分枝杆菌耐药基因的结果分析

目的 分析和探讨荧光PCR熔解曲线法对结核病的诊断和耐药检测的应用价值。方法 收集2015年9月至2016年12月新疆维吾尔自治区胸科医院的976例疑似结核病患者的痰标本,运用探针荧光PCR熔解曲线法来检测结核分枝杆菌及其对利福平、异烟肼的耐药突变情况。以BACTEC MGIT 960液体培养法及液体药敏试验检测结果为标准,评价探针荧光PCR熔解曲线法鉴定结核分枝杆菌及其耐药突变检测的敏感度、特异度、一致率、Kappa值等。结果 以MGIT 960液体培养结果为标准,荧光PCR熔解曲线法鉴定结核DNA的敏感度为85.44%(135/158),特异度为94.01%(769/818),Kappa值为0.75,诊断符合率为92.62%(904/976)。以MGIT 960液体药敏试验结果为标准,荧光PCR熔解曲线法对异烟肼耐药突变检测的敏感度为83.33%(20/24),特异度为94.59%(105/111),Kappa值为0.76,诊断符合率为92.59%(125/135);荧光PCR熔解曲线法对利福平耐药突变检测的敏感度为95.83%(23/24),特异度为95.50%(106/111),Kappa值为0.86,诊断符合率为95.56%(129/135)。结论 荧光PCR熔解曲线法检测速度快,对利福平和异烟肼耐药突变检测结果具有良好的敏感度和特异度,可用于临床上对结核分枝杆菌利福平和异烟肼耐药情况的快速筛查。     

Detection of Mycobacterium tuberculosis from sputum specimens using one-tube nested PCR

One-tube nested PCR was developed for diagnosis of pulmonary tuberculosis using sequences based on thel6SrRNA gene. The usage of primers 16SOL, 16SOR, 16SIL and 16SIR with optimized conditions could detect 555 bp DNA band from 21 species, 41 strains of mycobacteria and one isolate of Nocardia asteroides. It also revealed a specific 306 bp DNA band from 59 strains of M. tuberculosis complex. Cross amplification was observed in M. marinum, M. ulcerans and a few isolates of M. fortuitum complex. The developed method could detect as little as 100 fg of M. tuberculosis DNA. The PCR mixtures could be stored at 0 degrees C for 2 months or at -20 degrees C for at least 20 months without decrease in sensitivity. Using one-tube nested PCR for detection of M. tuberculosis compared with acid fast staining and culture results from 153 sputum specimens revealed 88.6% sensitivity and 89.2% specificity in smear positive specimens and 93.2% sensitivity and 85.0% specificity in culture positive specimens.     

Establishment and effect evaluation of polymerase spiral reaction for detection of Mycobacterium tuberculosis

目的 建立聚合酶螺旋反应(polymerase spiral reaction,PSR)检测结核分枝杆菌的方法并评价效果。方法 针对结核分枝杆菌插入序列IS6110设计引物进行PSR检测。提取结核分枝杆菌基因组DNA,加入Bst DNA聚合酶的RM2×反应液中,在荧光定量PCR仪上于63℃反应45min,通过荧光信号进行检测。通过对引物序列进行优化,筛选出最佳引物序列,并对其检测特异性和最低检出限进行评估。于2019年5—8月间从郑州市第六人民医院连续收集200例肺结核患者痰液样本(同一患者收集3份),对痰标本进行痰涂片、固体痰培养和PSR检测。以痰培养结果为参照,评价PSR对结核病患者的检测效能。结果 通过引物序列优化,筛选出一套对结核分枝杆菌检测的PSR引物,使用该引物进行PSR的最低检出限可达到10³菌落形成单位(CFU)/ml;检测特异性实验表明该方法与15株非结核分枝杆菌无交叉反应。200例肺结核患者中,痰涂片检测阳性48例,阳性检出率为24.0%(48/200);痰培养检测阳性83例,阳性检出率为41.5%(83/200);PSR方法检测阳性87例,阳性检出率为43.5%(87/200)。以痰培养结果为标准,PSR检测结核病的敏感度和特异度分别为96.4%(80/83)、94.0%(110/117),阳性预测值为92.0%(80/87),阴性预测值为97.3%(110/113),与痰培养检测方法基本一致(Kappa值为0.898)。结论 PSR检测适用于结核分枝杆菌的快速筛查。     

结核分枝杆菌聚合酶螺旋反应检测方法的建立及效果评价

目的 建立聚合酶螺旋反应(polymerase spiral reaction,PSR)检测结核分枝杆菌的方法并评价效果。方法 针对结核分枝杆菌插入序列IS6110设计引物进行PSR检测。提取结核分枝杆菌基因组DNA,加入Bst DNA聚合酶的RM2×反应液中,在荧光定量PCR仪上于63℃反应45min,通过荧光信号进行检测。通过对引物序列进行优化,筛选出最佳引物序列,并对其检测特异性和最低检出限进行评估。于2019年5—8月间从郑州市第六人民医院连续收集200例肺结核患者痰液样本(同一患者收集3份),对痰标本进行痰涂片、固体痰培养和PSR检测。以痰培养结果为参照,评价PSR对结核病患者的检测效能。结果 通过引物序列优化,筛选出一套对结核分枝杆菌检测的PSR引物,使用该引物进行PSR的最低检出限可达到10³菌落形成单位(CFU)/ml;检测特异性实验表明该方法与15株非结核分枝杆菌无交叉反应。200例肺结核患者中,痰涂片检测阳性48例,阳性检出率为24.0%(48/200);痰培养检测阳性83例,阳性检出率为41.5%(83/200);PSR方法检测阳性87例,阳性检出率为43.5%(87/200)。以痰培养结果为标准,PSR检测结核病的敏感度和特异度分别为96.4%(80/83)、94.0%(110/117),阳性预测值为92.0%(80/87),阴性预测值为97.3%(110/113),与痰培养检测方法基本一致(Kappa值为0.898)。结论 PSR检测适用于结核分枝杆菌的快速筛查。     

Fluorescein Diacetate Vital staining for detecting viability of acid-fast bacilli in sputum of pulmonary tuberculosis patients

ObjectiveTo compare the performance of the Fluorescein diacetate (FDA) vital staining method with Ziehl-Neelsen staining method in detecting the viability of acid-fast bacilli using MGIT culture as “reference standard”.MethodsThis was a single centre prospective observational study conducted from October 2015 to November 2016. Microbiologically confirmed ZN-Smear positive (3+) sputum specimens were obtained from 30 pulmonary tuberculosis patients taking anti-tuberculosis treatment at DOTS centre of NITRD, New Delhi. Patients were made available to collect the first baseline sputum sample before commencing treatment, and an early morning sputum sample was collected as per RNTCP guidelines. After starting treatment, sputum specimens were collected weekly in the first month and thereafter twice-weekly until 18th week. All sputum specimens from patients receiving anti-tuberculosis treatment were examined using Ziehl-Neelsen (ZN) smear microscopy, FDA vital staining, and MGIT culture.ResultOut of 360 follow up sputum specimens collected from 30 adult microbiologically confirmed ZN- Smear (3+) pulmonary tuberculosis patients, 146 were ZN-positive and 130 FDA-positive. Of 130 FDA-positive sputum samples, mycobacteria tuberculosis (MTB) growth was found in 116 sputum samples, of which 116 sputum specimens were positive for FDA. Additionally, 14 culture-negative specimens were FDA positive. No FDA-negative sputum samples were positive for MGIT culture. Among ZN positive specimens, FDA had 100% sensitivity and 85.3% specificity with an accuracy of 96.58% for the detection of viable mycobacteria. Among ZN negative sputum specimens, FDA had comparatively high specificity (95.7%). Using positive MGIT culture as a reference for viability, negative predictive value (NPV) and positive predictive value (PPV) from FDA vital staining method were found to be 100 and 89% respectively.ConclusionFDA staining is a simple and rapid tool for identifying viable MTB bacilli. Because of its excellent NPV and encouraging specificity, FDA staining is useful to identify patients with non-viable bacilli (FDA negative) among retreatment cases at diagnosis and patients on anti-tuberculosis treatment for both drug-sensitive and drug-resistant tuberculosis for follow up for the response of treatment.     

Efficacy of Amplicor PCR for the diagnosis of tuberculosis in respiratory specimens other than sputum.

A total of 832 respiratory specimens not including the sputum (402 bronchial lavages, 241 bronchial brushing specimens, 136 pumping lavages, 41 pleural effusions, and 12 others) from 462 patients were assayed using the Roche Amplicor Mycobacterium tuberculosis test for amplification and identification of M. tuberculosis, M. avium and M. intracellulare (Amplicor PCR). The results were compared with those obtained using conventional microscopy and cultivation methods. Each patient had little or no sputum and showed an abnormal chest X-ray shadowing of unknown cause. No patients had previously undergone antituberculous therapy. Of the specimens obtained, 24 were both PCR and culture positive, 786 were both PCR and culture negative, 11 were PCR positive and culture negative, and 11 were PCR negative and culture positive. Based on these results, the sensitivity and specificity of Amplicor PCR were determined to be 68.67% and 98.6%, respectively, when compared with culture of respiratory specimens not including the sputum. After correcting for discrepancies due to differences in patient clinical data, the sensitivity of Amplicor PCR was found to be 68.6%, and the specificity to be 99.9%; the corresponding values for culture were 66.7% and 100%, and those for smear were 9.8% and 100%. Thus, Amplicor PCR was shown to possess a similar sensitivity to culture and to be a highly specific technique for the diagnosis of tuberculosis in the respiratory system using non-sputum specimens within hours in patients showing little or no sputum and abnormal chest X-ray shadowing of an indeterminant cause.     

结核分枝杆菌L型检测的临床意义

目的　研究结核分枝杆菌L型(MTB L)检测的临床意义。方法 结核病 314例留痰 312份,前列腺液 1份,精液 1份,标本经消化调整PH值后,3800转 分离心沉淀 30分钟,取沉淀物接种92 TB L型培养基,进行MTB L培养,同时常规MTB培养对照。进行 (1)初复治肺结核、肺外结核、肺结核治愈者标本MTB、MTB L培养,阳性检出率统计。 (2)观察初治肺结核患者痰MTB L阳性与因症就诊时间关系。 (3)观察复治结核病MTB L阳性检出率与既往第一线用药品种数量关系。结果 314例MTB及MTB L均阳性的阳性检出率为 424%,MTB L阳性检出率为 28 7%,初治MTB L阳性者占菌阳总数的 64.8% (5991),并发现初治MTB L发生与就诊时间有关,超过 1个月与不超过 1个月阳性检出率相比差异有显著性 (P＜0.05)。复治MTB L阳性检出率占复治菌阳的72.50% (29 40),并与应用第一线抗结核药物品种数量有关,超过 4种药 3月以上与 1～3种药 3月以上相比,差异非常显著 (P＜0.01)。结论 MTB L检测对结核病诊断、判断活动性、考核疗效及指导临床治疗,尤其痰MTB阴性者治疗,有重要临床意义。初、复治患者及时就诊,正规治疗,是减少MTB L的形成的关键。     

Yield of smear, culture and amplification tests from repeated sputum induction for the diagnosis of pulmonary tuberculosis.

OBJECTIVES: To assess the yield of repeated sputum induction for the diagnosis of active tuberculosis in patients who do not produce spontaneous sputum, or with smear-negative spontaneous samples. METHODS: Induced sputum was examined with fluorescent microscopy, two amplification methods (PCR Amplicor MTB, and MTD2), and cultured for mycobacteria using liquid (Bactec 12B) and Lowenstein-Jensen media. Bronchoscopy and collection of other specimens were performed at the discretion of the treating physician. RESULTS: A total of 1115 sputum inductions performed in 500 patients without adverse events yielded an adequate specimen in 1113 (99.8%), and microbiological confirmation in 43 of 44 (98%) culture-positive active TB cases. Yield increased with repeated sputum induction. The cumulative yield for acid-fast bacilli smear and mycobacterial culture was 64% and 70% respectively for one, 81% and 91% for two, 91% and 99% for three, and 98% and 100% for four induced samples. Yield of PCR also increased with the greater number of induced samples tested. CONCLUSIONS: Repeated sputum induction could considerably improve diagnostic accuracy for pulmonary TB.     

应用PCR-SSCP技术检测痰中结核分枝杆菌katG、rpoB、embB基因突变的研究

目的应用PCR-SSCP技术检测痰样本中结核分枝杆菌katG、rpoB、embB基因突变,探索其临床应用价值。方法以结核分枝杆菌标准株H₃₇R_V为对照,应用套式PCR扩增目的基因,并使用SSCP技术直接检测100例耐药患者和10例敏感患者痰样本中结核分枝杆菌katG、rpoB、embB基因突变并进行基因测序,将SSCP结果及测序结果与细菌培养药敏结果进行比较分析。结果PCR-SSCP直接检测痰样本中的结核分枝杆菌katG基因突变的敏感性和特异性分别是55.9%和70.0%,rpoB为76.0%和90.0%,embB为46.4%和60.0%。结论PCR-SSCP操作快速、简单,敏感性和特异性较高,可用来直接检测临床痰样本中结核分枝杆菌katG、rpoB、embB基因突变。     

基因芯片技术在肺结核快速诊断及分枝杆菌菌种鉴定中的应用价值

目的探讨基因芯片技术诊断肺结核及鉴定分枝杆菌菌种的应用价值。方法搜集2017年1-12月在黑龙江省传染病防治院结核科就诊并连续3次痰涂片检测为阳性的1248例疑似肺结核患者为研究对象。每例患者均留取清晨痰液标本3~5ml,对痰液标本分别进行BACTEC MGIT 960(简称"MGIT 960")培养和基因芯片检测。以MGIT 960培养结果作为参照,分析基因芯片法的检测效能。结果1248例患者痰标本经MGIT960培养阳性1224例(98.08%),基因芯片法检测阳性1212例(97.11%)。以MGIT 960培养结果作为参照,基因芯片法检测的敏感度为98.94%(1211/1224),特异度为95.83%(23/24),符合率为98.88%(1234/1248),Kappa值为0.76。1212例基因芯片法检测阳性的患者中非结核分枝杆菌(NTM)感染60例(4.95%),结核分枝杆菌感染1152例(95.05%)。60例NTM感染者中比较常见的菌种是胞内分枝杆菌(43.33%,26/60)。结论基因芯片检测与MGIT 960培养结果的一致性较好,可以快速、准确地区分结核分枝杆菌复合群和NTM,并可进一步进行菌种鉴定。     

Method for efficient storage and transportation of sputum specimens for molecular testing of tuberculosis.

SETTING: The polymerase chain reaction (PCR) is a highly sensitive method for the detection of Mycobacterium tuberculosis and is available in most countries, though to a lesser extent in rural areas. OBJECTIVE: To amplify M. tuberculosis DNA sequences of sputum spotted on FTA cards and compare them with the results of microscopic examination among culture-positive samples. DESIGN: A total of 102 sputum specimens of TB patients in treatment were spotted on FTA cards and stored at room temperature until DNA analysis. We assessed the IS6110 region of M. tuberculosis. The efficacy of the PCR assay for the direct detection of M. tuberculosis was evaluated and compared with the results of cultures (Middlebrook 7H9 broth) and smears of fresh sputum specimens. RESULTS: We were able to detect 10 fg/microl of mycobacterial DNA even after 6 months in storage. The PCR sensitivity and specificity using the FTA card system were 82% and 96%, while microscopic examination showed 41% and 95%, respectively. CONCLUSION: The FTA card system for the storage of bacterial DNA from sputum samples should be considered for the molecular diagnosis of tuberculosis. Samples can easily be obtained from geographically isolated populations and shipped by mail for accurate molecular diagnosis.     

基因芯片法在结核分枝杆菌耐药基因快速诊断中的应用价值

目的 探讨基因芯片法在结核分枝杆菌耐药基因快速诊断中的应用价值。 方法 收集2017年6月至2018年6月厦门大学附属第一医院肺科门诊及住院的933例疑似肺结核患者初诊时采集的同一份晨痰标本,同时进行基因芯片法、GeneXpert MTB/RIF(简称“GeneXpert”)和BACTEC MGIT 960液体培养及其比例法药物敏感性试验(简称“MGIT 960及其比例法药敏试验”)3种方法进行结核分枝杆菌及其耐药性检测,对检测结果进行对比分析。 结果 933例患者的痰标本中,基因芯片法检测出阳性484例,GeneXpert检测出阳性462例,MGIT 960培养出阳性411例。三种检测方法均为阳性的标本有395例,采用Excel表通过完全随机的方式抽取232例进行耐药性检测,以比例法药敏试验结果为参考标准,基因芯片法检测出异烟肼耐药的敏感度为86.67%(26/30),特异度为96.53%(195/202),一致性为95.26%(221/232),Kappa值为0.798(0.682~0.914);检测出利福平耐药的敏感度为93.75%(30/32),特异度为97.00%(194/200),一致性为96.55%(224/232),Kappa值为0.862(0.768~0.956);GeneXpert检测出利福平耐药的敏感度为84.38%(27/32),特异度为97.00%(194/200),一致性为95.26%(221/232),Kappa值为0.803(0.691~0.915);基因芯片法与GeneXpert对利福平耐药检测的一致性为96.12%(223/232),Kappa值为0.847(0.749~0.945)。Kappa值均大于0.75,具有良好的一致性。 结论 以MGIT 960及其比例法药敏试验结果为标准,基因芯片法敏感度、特异度和一致性高,与GeneXpert也具有良好的一致性,有助于结核病的早期诊断及防控。     

Laboratory diagnosis of pulmonary tuberculosis in TB and HIV endemic settings and the contribution of real time PCR for M. tuberculosis in bronchoalveolar lavage fluid

Background Tuberculosis (TB) in Africa is increasing because of the human immunodeficiency virus (HIV) epidemic, and in HIV/AIDS patients it presents atypically. Pulmonary tuberculosis (PTB) in Africa is mainly diagnosed clinically, by chest radiograph or by sputum smear for acid fast bacilli (AFB). Methods We evaluated in 120 HIV‐infected patients with chest infection the diagnostic accuracy of AFB smear of sputum and bronchoalveolar lavage (BAL) fluid, sputum Mycobacterium tuberculosis (MTB) culture, real‐time PCR and MycoDot^® serological test, using MTB culture of BAL fluid as gold standard. We correlated PCR cycle threshold values (C_T) to the culture results. Retrospectively, we evaluated the development of active TB in patients with positive PCR but negative culture. Results Culture of BAL fluid identified 28 patients with PTB. Fifty‐six patients could not produce adequate sputum. Sputum AFB smear and the serological test had sensitivities of 66.7% and 0%, respectively. PCR with C_T 40 was positive in 73 patients, 27 of whom were also TB culture positive (96.4% sensitivity and 52.3% specificity of PCR). PCR with C_T 32 had sensitivity of 85.7% and specificity of 90.9% to diagnose PTB in BAL. No patients with positive PCR but negative culture developed active TB during 18 months follow‐up. Conclusion In these HIV‐infected patients, AFB smear and serology had very low sensitivities. PCR of BAL with C_T value 32 had improved specificity to diagnose active PTB. A prospective follow‐up study is warranted in TB/HIV endemic settings, applying real time PCR to both sputum and BAL.     

TaqMan聚合酶链反应技术检测结核分支杆菌DNA及其临？…

目的 探讨ＴａｑＭａｎ聚合酶链反应（ＴａｑＭａｎ－ＰＣＲ）技术在肺结构诊断中的价值。方法 对１６８例活动性肺结核、５７例肺癌患者的痰和外周血及３４－例健康对照外周血,同时应用ＴａｑＭａｎ－ＰＣＲ、ＰＣＲ检测,并与痰涂片法、ＢＡＣＴＥＣ法及改良罗氏培养法结果进行比较。结果 ＴａｑＭａｎ－ＰＣＲ检测痰和外周血总的阳性率分别为５３．０％和６１．３％,显著高于ＰＣＲ、痰涂片法、ＢＡＴＣＴＥＣ法及改良罗氏培