DNA体外扩增技术诊断关节结核的临床研究

目的：为探讨ＤＮＡ体外扩增（ｐｏｌｙｍｅｒａｓｅｃｈａｉｎｒｅａｃｔｉｏｎ，ＰＣＲ）技术对关节结核诊断的临床价值。材料与方法：对３０例关节结核和２０例非关节结核标本分别应用ＰＣＲ技术、抗酸染色镜检及分离培养法检测结核杆菌。结果：３０例关节结核中三种方法的阳性检出率分别为：ＰＣＲ法８７％，镜检法０，培养法１３％，ＰＣＲ法与镜检及培养法对于结核杆菌的阳性检出率比较，差异具有显著性意义（Ｐ值＜０．００５），ＰＣＲ法明显优于镜检及培养法。２０例非关节结核标本镜检及培养法均阴性，ＰＣＲ法阳性率１０％。盲法结核杆菌和对照菌ＰＣＲ检测结果表明，ＰＣＲ的特异性为１００％。ＰＣＲ扩增整个过程自动化控制，可在数小时内完成。结论：此表明ＰＣＲ技术检测关节结核标本结核杆菌具有快速、简便、特异与敏感等优点，对关节结核的早期快速诊断与鉴别诊断具有重要价值。     

聚合酶链反应对关节结核病诊断与鉴别诊断的临床价值

为探讨聚合酶链反应对关节结核病诊断与鉴别诊断的临床价值，对３０例关节结核和２０例非关节结核标本分别采用ＰＣＲ，抗酸染色镜检与分离增减法检测结核杆菌。结果３０例关节结核标本中阳性检率分别为ＰＣＲ地８７％，镜检法０，培养法１３％。     

聚合酶链反应检测结核杆菌DNA对骨结核病诊断的临床价值

采用聚合酶链反应（ＰＣＲ），分别对２０例骨结核患者标本用两种方法检查的阳性率分别为：培养法２０％，ＰＣＲ６５％，经统计学处理二种方法有显著性差别，ＰＣＲ阳性率显著高于培养法，而且２天即可报告，显著缩短了报告时间。３０例非骨结核中患者标本两种方法均为阴性。盲法结核杆菌和对照菌ＰＣＲ结果表明具有较高的特异性。只要标本中有结核杆菌ＤＮＡ即可扩增其特异的ＤＮＡ片断，即使经福尔马林固定２－４周的酝酿也可检测     

聚合酶链反应与分离培养技术检测结核分支杆菌诊断关节结核的对照研究

目的：研究聚合酶链反应（polymerase chain reaction,PCR）技术在关节结核标本结核分支杆菌检测方面的作用,探讨PCR技术对关节结核诊断的临床价值。方法：自1993年6月至2001年8月,对95例（男55例,女40例;年龄2～75岁）关节结核标本分别应用PCR技术和分离培养法盲法检测结核分支杆菌,计算两者检测阳性率,通过统计学处理进行比较。结果：95例关节结核标本结核分支杆菌检测中,PCR技术检测阳性78例,阴性17例,阳性率82％;分离培养法检测阳性15例,阴性80例,P13性率16％。PCR技术与分离培养法比较,Х^2=67,P〈0．001,两种方法对于关节结核标本结核分支杆菌的检出率比较差异有统计学意义。PCR扩增整个过程自动化控制,可在数小时内完成。结论：PCR技术检测关节结核标本具有快速、简便、敏感与特异等优点,明显优于分离培养,对关节结核的早期快速诊断与鉴别诊断具有较重要的临床价值。     

尿液肿瘤细胞快速荧光染色的检测及应用

用７６９０－ＸＵ荧光色液，对５００例次尿标本进行了荧光染色镜检，１２６例肿瘤标本中检出肿瘤细胞１１４例次，５０例次肿瘤尿液标本同时进行苏木素伊红染色（ＨＥ染色）镜检，检出肿瘤细胞２５例次，肿瘤病人均进行了膀胱镜及病理学证实，荧光染色镜检与临床最后诊断的符合率为９１％，ＨＥ染色镜检符合率为５０％。本染色法简便、快速、准确率高，可以应用于泌尿系统肿瘤，尤其是膀胱癌的早期诊断及术后追踪。     

手部慢性特殊感染病灶中分支杆菌的检测

目的探讨应用Nest-PCR检测技术对普通细菌培养阴性的手部慢性特殊感染患者提供有效的诊治依据。方法对15例手部慢性特殊感染病灶，除一般的病理、普通及特殊细菌培养、直接抗酸染色检查外，应用Nest-PCR技术来检测感染病灶中的分支杆菌，并对分支杆菌进行核酸测序分型。结果15例中普通及特殊细菌培养、直接抗酸染色均呈阴性。病理检查：结核性肉芽肿1例，结核样肉芽肿3例，结节性肉芽肿4例，慢性肉芽肿性炎7例。应用Nest—PCR检测技术，测出9例为非结核分支杆菌(Non-tuberculous myrcobacterium，NTM)阳性，结核杆菌为0。经核酸测序分型属海分支型5例，堪萨斯／胃型2例，鸟分支型1例，龟／脓肿型1例。结论Nest-PCR检测弥补了肺外分支杆菌培养阳性率低下的缺陷，证实了NTM感染，尤其是海分支杆菌远比结核菌常见，是沿海地区手部慢性特殊感染的主要致病因素。     

脊柱结核脓液中结核杆菌的复苏培养

目的：探讨结核杆菌复苏因子（rpf）对脊柱结核脓液中结核杆菌生长的影响。方法：由宁夏医学院第一附属医院骨科提供的临床诊断为脊柱结核的住院患者手术获取的脓液标本25份,氢氧化钠溶液常规处理后,每份标本分为低浓度培养组、高浓度培养组和对照组。高浓度和低浓度组各设6管,分别含高、低两种浓度的rpfA、B、C、D、E及各种复苏因子组合,每管中加入7ml7H9液体培养基,并加入处理后的标本和相应的rpf;对照组1管,不加rpf。37℃培养,分别在第6天、第11天、第16天、第30天检测培养物600nm处的吸光度（OD值）,同时于上述各时间点每管取10!l培养物涂7H11平板培养,取第30天培养物行抗酸染色检查,以证实培养物为结核杆菌。同时将处理后的脓液标本进行集菌法涂片抗酸染色和改良罗氏培养检测结核杆菌。结果：结核杆菌复苏培养阳性率（84%）显著高于涂片阳性率（60%）和改良罗氏培养阳性率（44%）（P〈0.05或0.01）。复苏培养低浓度各组与高浓度各组在培养第11天、第16天和第30天时培养物OD值均显著高于对照组（P〈0.05）;复苏培养同一组内第11天、第16天和第30天时培养物OD值均显著高于第6天（P〈0.01）,而第16天和第30天与第11天比较无显著性差异（P〉0.05）;对照组第11天、第16天和第30天培养物OD值与第6天比较均无显著性差异（P〉0.05）;同一时间、同一浓度时,5种复苏因子单独应用与联合应用之间两两比较,除高浓度rpfA、B在培养第30天时分别与同一浓度、同一时间的rpfC、D、E和组合组之间及rpfA与B之间比较有显著性差异（P〈0.05）外,其余均无显著性差异;同一种复苏培养,在同一时间高、低浓度比较,第30天时高浓度rpfA、B的OD值高于低浓度rpfA、B（P〈0.05）,低浓度rpfD高于高浓度rpfD（P〈0.05）,其余均无显著性差异。11例改良罗氏培养阳性和21例复苏培养阳性者的培养生长物抗酸染色检查均为抗酸杆菌,复苏培养生长物7H11平板培养第20d时可见淡黄色菜花状菌落,证实为结核杆菌。结论：结核杆菌复苏因子能有效促进脊柱结核脓液中结核杆菌的迅速生长,复苏培养法能提高脊柱结核脓液中结核杆菌的检出率。     

Xpert MTB/RIF在骨关节结核患者快速诊断中的应用

目的:探讨Xpert MTB/RIF在骨关节结核患者快速诊断中的应用价值。方法:2014年2月~2014年11月使用Xpert MTB/RIF对49例骨关节结核患者及32例非结核性骨关节病患者的脓液标本进行检测,以临床诊断为金标准,计算Xpert MTB/RIF检测结核分枝杆菌的敏感性、特异性、阳性预测值、阴性预测值、一致率;同时对脓液标本行抗酸染色及结核分枝杆菌快速培养(BACTECT MGIT960),比较Xpert MTB/RIF与抗酸染色、结核分枝杆菌快速培养在敏感性及特异性上的差异;综合上述两方面因素评价Xpert MTB/RIF在骨关节结核患者快速诊断中的应用价值。结果:Xpert MTB/RIF检测单个脓液标本的时间为2.3±0.2h。49例骨关节结核患者脓液标本中,46例Xpert MTB/RIF检测结核分枝杆菌阳性,3例Xpert MTB/RIF阴性;32例非结核性骨关节病患者脓液标本中,1例Xpert MTB/RIF检测结核分枝杆菌阳性,31例Xpert MTB/RIF阴性;以临床诊断为金标准,Xpert MTB/RIF检测结核分枝杆菌的敏感性为93.87%、特异性为96.87%、阳性预测值为97.87%、阴性预测值为91.17%,一致率为95.06%。在46例Xpert MTB/RIF结核分枝杆菌阳性的骨关节结核患者中,10例存在利福平耐药突变基因,耐药突变率为21.73%。49例骨关节结核患者脓液标本中,抗酸染色阳性8例,阴性41例,敏感性为17.39%;结核分枝杆菌快速培养阳性患者11例,阴性38例,敏感性为23.91%;32例非结核性骨关节病患者脓液标本抗酸染色及结核分枝杆菌快速培养均为阴性,其特异性均为100%。Xpert MTB/RIF检测结核分枝杆菌的的敏感性优于抗酸染色及结核分枝杆菌快速培养(P0.05),特异性与抗酸染色及结核分枝杆菌快速培养无明显差异(P0.05)。结论:Xpert MTB/RIF在骨关节结核患者的快速诊断中具有较高的诊断效能,其耗时短,敏感性高,特异性强,与抗酸染色及结核分枝杆菌快速培养比较具有明显优势。     

PCR技术在快速诊断艾滋病合并播散性马尔尼菲青霉菌病中的应用

目的探讨PCR技术在快速诊断艾滋病（AIDS）合并播散性马尔尼菲青霉病（PSM）中的应用价值。方法收集21例AIDS合并播散性PSM患者抗真菌治疗前的系列标本：未培养血液、阳性血液培养物和阳性骨髓培养物,以12例健康人血液为阴性对照。提取上述标本的基因组DNA,采用真菌通用引物ITS1和ITS4对基因组DNA进行PCR扩增,扩增产物测序后与GenBank核酸序列数据库进行比对分析。结果 21份阳性血液培养物、21份阳性骨髓培养物及2份未培养血液标本均扩增出目的条带,而12份健康人血液标本未扩增出条带。阳性PCR产物测序结果与广东、日本、泰国、印度尼西亚的马尔尼菲青霉菌（PM）rDNA ITS序列（登录号分别为AB298970、AB298950、L37406、AJ853738）一致性高达97%～100%,证实为PM。PM与新型隐球菌及烟曲霉菌rDNA ITS序列的遗传距离最远,与青霉菌属其他菌种绳状青霉菌和桔青霉菌rDNAITS序列的遗传距离最近。结论 PCR可敏感、特异的检测出培养阳性标本中PM,并能有效缩短PM检出时间,但直接采用患者血液进行PCR检测的阳性率较低,方法有待改进。     

Xpert MTB/RIF在骨关节结核患者

【摘要】 目的：探讨Xpert MTB/RIF在骨关节结核患者快速诊断中的应用价值。方法：2014年2月~2014年11月使用Xpert MTB/RIF对49例骨关节结核患者及32例非结核性骨关节病患者的脓液标本进行检测,以临床诊断为金标准,计算Xpert MTB/RIF检测结核分枝杆菌的敏感性、特异性、阳性预测值、阴性预测值、一致率;同时对脓液标本行抗酸染色及结核分枝杆菌快速培养（BACTECT MGIT 960）,比较Xpert MTB/RIF与抗酸染色、结核分枝杆菌快速培养在敏感性及特异性上的差异;综合上述两方面因素评价Xpert MTB/RIF在骨关节结核患者快速诊断中的应用价值。结果：Xpert MTB/RIF检测单个脓液标本的时间为2.3±0.2h。49例骨关节结核患者脓液标本中,46例Xpert MTB/RIF检测结核分枝杆菌阳性,3例Xpert MTB/RIF阴性;32例非结核性骨关节病患者脓液标本中,1例Xpert MTB/RIF检测结核分枝杆菌阳性,31例Xpert MTB/RIF阴性;以临床诊断为金标准,Xpert MTB/RIF检测结核分枝杆菌的敏感性为93.87%、特异性为96.87%、阳性预测值为97.87%、阴性预测值为91.17%,一致率为95.06%。在46例Xpert MTB/RIF结核分枝杆菌阳性的骨关节结核患者中,10例存在利福平耐药突变基因,耐药突变率为21.73%。49例骨关节结核患者脓液标本中,抗酸染色阳性8例,阴性41例,敏感性为17.39%;结核分枝杆菌快速培养阳性患者11例,阴性38例,敏感性为23.91%;32例非结核性骨关节病患者脓液标本抗酸染色及结核分枝杆菌快速培养均为阴性,其特异性均为100%。Xpert MTB/RIF检测结核分枝杆菌的的敏感性优于抗酸染色及结核分枝杆菌快速培养（P<0.05）,特异性与抗酸染色及结核分枝杆菌快速培养无明显差异（P>0.05）。结论：Xpert MTB/RIF在骨关节结核患者的快速诊断中具有较高的诊断效能,其耗时短,敏感性高,特异性强,与抗酸染色及结核分枝杆菌快速培养比较具有明显优势。     

Rapid diagnosis of genitourinary tuberculosis by polymerase chain reaction and non-radioactive DNA hybridization

OBJECTIVE: To establish a polymerase chain reaction (PCR) assay for the rapid detection and identification of mycobacteria in urine, and to assess the value of such assay in routine laboratory diagnosis of genitourinary tuberculosis. MATERIALS AND METHODS: Urine specimens from 1000 patients with clinical suspicion of urinary tuberculosis were examined. Two assays for the detection and identification of Mycobacterium tuberculosis (M. tuberculosis) complex and mycobacteria other than tuberculosis (MOTT) by non-radioactive DNA hybridization of PCR-product were applied. The first assay used PCR primers and probe derived from M. tuberculosis species-specific DNA insertion sequence, IS6110. The second utilized mycobacterium genus-specific sequence encoding ribosomal ribonucleic acid (16S rRNA). The results obtained by PCR were compared with those obtained by standard microbiological methods, acid-fast bacilli (AFB) stain and culture. RESULTS: Compared with cultures, the sensitivity of AFB staining was 52.07% and the specificity was 96.7%. In comparison to the results of culture, the overall sensitivity and specificity of the IS6110-PCR assay was 95.59% and 98.12% respectively. While the corresponding results for the 16S rRNA gene-PCR were 87.05% and 98. 9%. CONCLUSION: The high sensitivity and specificity in addition to the potential for rapid detection of mycobacteria, makes this test a useful tool in the clinical management of mycobacterial infection in urine. Urine specimens may contain M. tuberculosis and/or other mycobacteria; therefore, there are advantages in using genus-specific primers in parallel with species-specific primers in PCR assay.     

聚合酶链反应技术诊断泌尿系结核

采用聚合链反应（ＰＣＲ）技术快速检测尿液标本中结核相菌ＤＮＡ，显示敏感性为９２％特异性为８８％，阳性预测７９％，阴性预测９６％，可靠性为８９％，认为ＰＣＲ是临床快速诊断泌尿系结核的有效方法之一，优于现行病原学检查法，适合临床推广应用。     

Clinical value of polymerase chain reaction in the diagnosis of joint tuberculosis by detecting the DNA of Mycobacterium tuberculosis

Objective: To assess the clinical value of polymerase chain reaction (PCR) in the diagnosis and differential diagnosis of joint tuberculosis (TB). Methods: PCR was used blindly to detect the DNA of Mycobacterium tuberculosis (M.TB) in five specimens of M.TB, 5 of BCG, and 10 of other bacteria. Then, M. TB in 98 samples from patients with joint TB and 100 samples from patients with non‐tubercular joint disorders were detected by PCR, acid‐fast staining and culture,. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PCR were calculated. The χ2 test was used for statistical analysis of the frequency of various factors. At the same time, some problems with PCR were also systematically analyzed. Results: (1) In the “standard samples”, both M. TB and BCG showed positive while other bacteria were negative. (2) In 98 cases from patients with joint TB, 81 were positive by PCR, 6 by acid‐fast staining, and 17 by culture. In 100 cases from patients with non‐tuberculous joint disorders, 9 were positive by PCR, and none by either acid‐fast staining or culture. Sensitivity, specificity, accuracy, positive and negative predictive value of PCR were 82.65% (81/98), 91.00% (91/100), 86.87% (172/198), 90.00% (81/90) and 84.26% (91/108), respectively. (3) The positive rates for PCR, acid‐fast staining and culture in detection of M. TB were 82.65% (81/98), 6.12% (6/98), and 17.34% (17/98), respectively. There were statistically significant differences between the three methods (P < 0.001). (4) The process of PCR is automatic, and can be completed within 3 to 6 hours, whereas 4 to 8 weeks are required for the conventional culture of M. TB. Conclusion: PCR is a sensitive, specific, rapid, simple and minimally invasive method for detection of M. TB in samples from joint TB, and can play an important role in early and rapid diagnosis and differential diagnosis of joint TB. But it also has some limitations, such as false positivity and false negativity.     

Identification of HIV patients with active pulmonary tuberculosis using urine based polymerase chain reaction assay

BACKGROUND: Despite the increased dissemination of tuberculosis among HIV infected patients, the diagnosis is difficult to establish. Traditional microbiological methods lack satisfactory sensitivity. We have developed a highly sensitive and specific nested polymerase chain reaction (PCR) capable of detecting Mycobacterium tuberculosis DNA in urine specimens and have used this test to examine urine specimens from HIV patients with active pulmonary tuberculosis. METHODS: Urine specimens from 13 HIV infected patients with microbiologically proven active pulmonary tuberculosis, 10 AIDS patients with non-tuberculous mycobacterial infection (documented by blood culture), 53 AIDS patients with no evidence of mycobacterial disease, and 80 healthy subjects (25 with positive skin test to purified protein derivative) were tested for M tuberculosis using PCR, acid fast staining (AFS), and culture. RESULTS: Of the urine specimens from patients with active tuberculosis, all tested positive by PCR, two by culture, and none by AFS. No reactivity was observed in urine specimens from patients with non-tuberculous mycobacterial infection. Of the 53 AIDS patients without mycobacterial infection, one had a positive urine PCR. Normal subjects were all negative. CONCLUSIONS: Urine based nested PCR for M tuberculosis may be a useful test for identifying HIV patients with pulmonary tuberculosis.     

Usefulness of 23S rRNA amplification by PCR in the detection of bacteria in CAPD peritonitis

BACKGROUND: Peritonitis is the most common complication of continuous ambulatory peritoneal dialysis (CAPD), and the spectrum of organisms causing CAPD peritonitis is broad. Polymerase chain reaction (PCR) has recently broadened its diagnostic capabilities in infectious diseases. PCR can provide a sensitive method for identifying causative infectious organisms. METHODS: To evaluate the usefulness of 23S bacterial ribosomal RNA amplification and direct sequencing for the detection of infectious organisms, we compared PCR with bacteriological culture for the analysis of dialysates from CAPD peritonitis patients. Thirty-two samples from CAPD peritonitis patients with current antibiotic use and control samples from 30 CAPD patients without peritonitis were examined by PCR with sequencing analysis and by conventional bacteriological culture. In addition, 95 culture-positive samples and 39 culture-negative samples from CAPD peritonitis patients before antibiotic treatment were analyzed by PCR assay. RESULTS: In the control samples from patients without CAPD peritonitis, false-positive rates were relatively rare: 3 of 30 in the PCR study and 2 of 30 in the culture study. Of the 134 CAPD peritonitis samples collected before antibiotic therapy, positive cultures were obtained in 70.9% (95/134) of them. In 75 of the culture-positive samples, the same microorganisms were confirmed by PCR assay, and the others showed discrepant results as compared with culture study. In 30 of the 39 culture-negative samples, microbial organisms were detected by PCR assay. Of the 32 samples from patients who developed CAPD peritonitis during antibiotic treatment, 17 (53.1%) were positive by PCR assay, and 5 (15.6%) were positive by culture. CONCLUSION: Our study suggests that broad-spectrum PCR with RNA sequencing can complement culture methods in the diagnosis of CAPD peritonitis, especially in patients with previous or current antibiotic use.     

Xpert MTB/RIF在脊柱结核诊断及利福平耐药检测中的应用价值

目的:探讨Xpert MTB/RIF技术在脊柱结核诊断及利福平耐药检测中的应用价值。方法:选取109例初步诊断为脊柱结核患者的脓液标本,分别行抗酸染色、BACTEC MGIT 960液体快速培养和Xpert MTB/RIF试验,对比3种检测结核分枝杆菌的敏感性及特异性的差异。对不同方法获取的脓液标本行Xpert MTB/RIF检测,评估脓液标本本身对Xpert MTB/RIF检测结核分枝杆菌效能的影响。以BACTEC MGIT 960液体快速培养药敏试验结果为金标准,分析Xpert MTB/RIF检测利福平耐药的效能。结果:抗酸染色、BACTEC MGIT 960液体快速培养及Xpert MTB/RIF检测的总体敏感性分别为25.92%、48.15%和77.78%。Xpert MTB/RIF检测开放手术、B超定位穿刺和穿刺活检取得脓液标本的敏感性分别为83.78%、76.47%和44.68%。以BACTEC MGIT 960液体快速培养药敏试验结果为金标准,Xpert MTB/RIF检测利福平耐药的敏感性和特异度分别为80%(4/5)和90.70%(39/43)。结论:Xpert MTB/RIF试验对脊柱结核具有较高的诊断价值,同时能对利福平耐药菌株进行检测,脓液标本中结核分枝杆菌含量对Xpert MTB/RIF检测的敏感性影响较大。     

多聚酶链反应检测尿中结核杆菌的临床意义

应用多聚酶链反应（ＰＣＲ）对８６例患者（１０例经病理诊断为肾结核，６９例可疑肾结核，７例单纯附睾结核）和３０例健康对照者进行连续２日晨尿结核菌检测。１０例肾结核患者检出均阳性；可疑肾结核者第一次检出９例，第二次为６例；７例附睾结核者两次无一阳性；对照组有１例二次检查均为阳性。认为ＰＣＲ对尿中结核杆菌检出率高、准确、快速，值得在临床上推广应用。     

广西HIV感染者呼吸道非结核分枝杆菌定植情况和临床特点分析

目的呼吸道非结核分枝杆菌定植是HIV感染者发生播散性非结核分枝杆菌感染的危险因素,并可能对肺结核的诊断造成干扰。我国HIV感染者中非结核分枝杆菌呼吸道定植情况和临床特点目前尚无较大样本的研究报道。本文分析HIV感染者痰培养中非结核分枝杆菌的阳性率和相关因素,从而总结其临床特点。方法 2006年8月至2008年7月,对广西省4个诊疗机构中CD4〈350的HIV感染者进行临床症状、胸片、痰涂片,痰分枝杆菌培养和血液分枝杆菌培养在内的结核筛查。结果 1073例HIV感染者在结核筛查时进行了痰分枝杆菌培养,检出非结核分枝杆菌87例（8.1%）,129例（12.0%）为结核分枝杆菌。在痰培养阳性的标本中,43%为非结核分枝杆菌。非结核分枝杆菌在呼吸道的定植率随着患者CD4水平降低而逐渐升高,在CD4计数〉200/μl、100～200/μl、50～100/μl和〈50/μl的患者组中分别为2.8%、6.4%、7.1%和9.8%。痰涂片抗酸杆菌阳性的患者中12.0%为非结核分枝杆菌,非结核分枝杆菌呼吸道定植的患者中8.5%痰涂片结果为抗酸杆菌阳性。与痰培养阴性的患者相比,有呼吸道非结核分枝杆菌定植的患者CD4水平较低,除体重下降更多见外,其他临床症状如发热、咳嗽、盗汗、乏力等,以及胸片异常表现均未增加。结论我国HIV感染者中痰培养非结核分枝杆菌的阳性率较高,尤其是在CD4〈200的患者中,需要加强临床观察。在未有进行细菌培养的情况下,非结核分枝杆菌在呼吸道的定植可能造成结核的误诊,应给予重视。     

The ligase chain reaction as a primary screening tool for the detection of culture positive tuberculosis

BACKGROUND: The ligase chain reaction Mycobacterium tuberculosis assay uses ligase chain reaction technology to detect tuberculous DNA sequences in clinical specimens. A study was undertaken to determine its sensitivity and specificity as a primary screening tool for the detection of culture positive tuberculosis. METHODS: The study was conducted on 2420 clinical specimens (sputum, bronchoalveolar lavage fluid, pleural fluid, urine) submitted for primary screening for Mycobacterium tuberculosis to a regional medical microbiology laboratory. Specimens were tested in parallel with smear, ligase chain reaction, and culture. RESULTS: Thirty nine patients had specimens testing positive by the ligase chain reaction assay. Thirty two patients had newly diagnosed tuberculosis, one had a tuberculosis relapse, three had tuberculosis (on antituberculous therapy when tested), and three had healed tuberculosis. In the newly diagnosed group specimens were smear positive in 21 cases (66%), ligase chain reaction positive in 30 cases (94%), and culture positive in 32 cases (100%). Using a positive culture to diagnose active tuberculosis, the ligase chain reaction assay had a sensitivity of 93.9%, a specificity of 99.8%, a positive predictive value of 83.8%, and a negative predictive value of 99.9%. CONCLUSIONS: This study is the largest clinical trial to date to report the efficacy of the ligase chain reaction as a primary screening tool to detect Mycobacterium tuberculosis infection. The authors conclude that ligase chain reaction is a useful primary screening test for tuberculosis, offering speed and discrimination in the early stages of diagnosis and complementing traditional smear and culture techniques.