Xpert MTB/RIF在人类免疫缺陷病毒感染/艾滋病患者中诊断结核病的价值

为探讨利福平耐药结核分枝杆菌实时荧光定量核酸扩增检测技术(Xpert Mycobacterium tuberculosis/rifampicin,Xpert MTB/RIF)在人类免疫缺陷病毒感染/艾滋病(human immunodeficiency virus infection/acquired immunodeficiency syndrome,HIV/AIDS)患者中诊断结核病的价值,本研究回顾性分析了2018年1月1日—2020年12月31日复旦大学附属公共卫生临床中心感染与免疫科收治的801例HIV/AIDS合并疑似结核病患者的临床资料。801例患者中,657例进行了Xpert MTB/RIF、外周血结核感染T细胞斑点试验(tuberculosis T cell spot test,T-SPOT.TB)、抗酸染色涂片镜检和BACTEC MGIT 960液体培养等检测。以液体培养及菌型鉴定结果作为结核病诊断的“金标准”,确诊结核病92例,Xpert MTB/RIF、T-SPOT.TB、抗酸染色涂片镜检在HIV/AIDS患者中诊断结核病(包括肺结核和肺外结核)的灵敏度分别为72.8%、55.4%和69.6%,特异度分别为96.8%、90.3%和84.4%,与“金标准”行一致性检验,Kappa值分别为0.719 (P<0.01)、0.430(P<0.01)和0.424(P<0.01)。Xpert MTB/RIF检测502份呼吸道样本,结果显示其诊断肺结核的灵敏度和特异度分别为66.7%和96.0%;在痰涂片阳性和阴性的患者中,Xpert MTB/RIF诊断肺结核的灵敏度分别为77.4%和35.2%,特异度分别为87.7%和 97.8%。采用Xpert MTB/RIF检测343份肺外标本,结果显示其诊断肺外结核的灵敏度和特异度分别为63.3%和95.2%。以上结果提示,Xpert MTB/RIF在HIV/AIDS患者中诊断结核病(包括肺结核和肺外结核)具有较高的灵敏度和特异度,诊断肺结核的灵敏度高于肺外结核,因此推荐将其作为HIV/AIDS患者疑似结核病的首选检测方法。     

应用GeneXpert MTB/RIF对肺外结核的快速检测及评估

目的评估GeneXpert MTB/RIF检测肺外结核分枝杆菌的准确性,并与传统方法进行比较。方法选取2016年6月至2017年6月在本院就诊的144例疑似肺外结核病患者,对所有标本分别进行金胺“O”荧光染色镜检、液体培养及药敏试验、固体培养及比例法体外药敏试验和Xpert法检测。结果收集的144例疑似肺外结核标本中,确诊108例,以胸水、淋巴结活检和脓液感染较多,另36例阴性患者中,10例为非结核分枝杆菌感染。Xpert试验的敏感性为28.73%,特异性为96.00%,其阳性预测值和阴性预测值均高于其他3种检测方法。在阳性检出率方面,Xpert试验高于涂片镜检(χ~2=17.39,P0.05)、低于液体培养(χ~2=8.64,P0.05),而与固体培养之间差异无统计学意义(χ~2=2.56,P0.05)。固体培养、液体培养和Xpert试验3种方法对结核分枝杆菌利福平耐药率检测差异无统计学意义(P0.05),耐药率分别为8.33%、9.68%和11.11%,且Xpert试验方法检测出2株耐多药结核分枝杆菌,平均耗时2.5 h。结论 GeneXpert MTB/RIF可以作为一种筛选及快速检测工具应用于肺外结核的诊断,同时可作为检测MDR-TB的一种指标。     

上海口岸2014-2015年入境人员肺结核筛查情况

为了解上海口岸入境人员肺结核的筛查情况及后续处理,防止结核病通过口岸跨境传播,本研究于2014年1月—2015年12月对所有在上海口岸办理入境体检的14岁以上人员进行结核病筛查,通过病史、体格检查和胸部X线摄影筛查疑似肺结核患者;对疑似肺结核患者进行痰细菌学检测、T‐SPOT ．TB和 Xpert MTB／RIF检测。结果显示,2014—2015年上海口岸入境人员共检出疑似肺结核患者215例,总检出率为229．76／10万;确诊肺结核患者33例,总检出率为35．27／10万,确诊率为15．3％。对210例疑似肺结核患者进行痰细菌学检测,结果显示结核分枝杆菌培阳率为14．3％,非结核分枝杆菌培阳率为17．1％。有95例和78例疑似肺结核患者分别接受 T‐SPOT ．TB和 Xpert MTB／RIF 检测,以痰细菌学检测为“金标准”,T‐SPOT ．TB的灵敏度为100％,特异度为49．4％;Xpert MTB／RIF的灵敏度为87．5％,特异度为96．8％。33例确诊肺结核患者中,25例（75．8％）离境,15例（45．5％）在离境前接受抗结核治疗,8例（24．2％）失访。本研究显示,上海口岸入境人员中肺结核确诊率仍有待提高。筛查与诊断中,T‐SPOT ．TB具备较高灵敏度, Xpert MTB／RIF具备较高特异度,两种方法均有较高应用价值,两者联用可提高检出率,缩短检出时间。对确诊病例或未确诊的可疑病例应加强后续监管。     

不同放散试验对新生儿ABO溶血病的诊断价值对比

摘要 目的：分析与比较不同放散试验对新生儿ABO溶血病的诊断价值。方法：选择2017年9月至2019年6月在本院进行ABO溶血病检测的新生儿240例,取所有新生儿的静脉血样本2~3 mL,采用冷冻复融放散试验方法与改良热放散试验方法检测新生儿ABO溶血病的发生情况,并比较单独诊断和联合诊断的价值。结果：在240份标本中,冷冻复融放散试验检出新生儿ABO溶血病阳性130例,阳性检出率为54.2 %;改良热放散试验检出新生儿ABO溶血病阳性94例,阳性检出率为39.2 %;二者联合检出新生儿ABO溶血病阳性100例,阳性检出率为41.67 %,联合检出新生儿ABO溶血病阳性率和冷冻复融放散试验检出新生儿ABO溶血病阳性率显著高于改良热放散试验检出新生儿ABO溶血病阳性率(P<0.05)。临床最终诊断为新生儿ABO溶血病101例,阳性率为42.08 %,患儿ABO血型包括A型56例,B型45例。冷冻复融放散试验诊断新生儿ABO溶血病的敏感性和特异性为73.8 %和95.5 % ,ROC曲线面积0.775;改良热放散试验检诊断为新生儿ABO溶血病的敏感性和特异性为100 %和95.2 %,ROC曲线面积0.853;二者联合诊断对新生儿ABO溶血病的敏感性和特异性为90.0 %和97.85 %,ROC曲线面积0.872,联合诊断特异性优于改良热放散试验检诊和冷冻复融放散试验诊断,且改良热放散试验检诊敏感性优于冷冻复融放散试验诊断。结论：相对于冷冻复融放散试验,改良热放散试验对新生儿ABO溶血病的诊断敏感性更高,且不影响诊断特异性,两种放散方法联合检测具有更好的应用价值。     

胸部CT结合AI诊断系统对疑似肺结节患者的诊断及对结节类型的评估价值

摘要 目的：探讨胸部CT结合AI诊断系统对疑似肺结节患者的诊断及对结节类型的评估价值。方法：选取2019年12月-2020年12月在我院进行CT检查的358例疑似肺结节患者,将其按照随机数字表法分为两组：对照组（放射科医生根据CT扫描结果,通过人工阅片分析记录检出结节数量和影像特征）,观察组（将CT扫描结果导入AI辅助诊断系统,经AI运算得到结节检出数量和影像特征）。AI辅助系统IMsight用于肺结节的图像分析和自动检测。通过组织病理学确定结节的良恶性。绘制受试者工作特征曲线（ROC）曲线以评估AI和CT结合图像的诊断价值。结果：病理结果最后确诊结节数量736个,恶性结节139个（18.89 %）,良性结节597个（81.11 %）。观察组诊断结节数量717个,检出率97.42%,对照组诊断出结节数量603个,检出率81.93 %。观察组较对照组的结节检出率、阳性检出率升高（P<0.05）,漏检率和假阴性率均显著降低（P<0.05）。当结节小于10 mm时,观察组较对照组的检出率升高（P<0.05）,观察组较对照组对磨玻璃密度结节和实性结节检出率升高（P<0.05）,观察组较对照组位于胸膜结节检出率升高（P<0.05）。观察组较对照组AUC（P<0.05）,表明AI系统下的结节检出准确率高。ROC曲线显示观察组的敏感性和特异性分别为88.39%和89.68 %,对照组的敏感性和特异性分别为75.24 %和82.34 %,观察组较对照组的ROC曲线敏感性和特异性升高（P<0.05）。结论：AI辅助诊断系统可有效提高肺结节的检出率,减少误检率及漏检率,值得在肺结节CT检测中应用推广。     

先天性心脏病"双期三步法"筛查诊断流程推广应用初探

摘要 目的：分析"双期三步法"筛查诊断流程在西安咸阳地区新生儿先天性心脏病筛查中的推广与应用价值。方法：选取2021年1月1日-2021年12月31日在医院产检的胎儿和出生的新生儿作为研究对象，收集胎儿期、新生儿期和婴儿期的先心筛查数据，将新生儿分为杂音组、经皮氧饱和度阳性组、双阳性组，评价"双期三步法"筛查方法的使用价值。结果：共对12318例新生儿进行了筛查，筛查阳性497例。确诊126例，实际发病率为10.23‰。在确诊的例先心病患儿中，位于前3位的疾病类型分别为房间隔缺损66例（52.38%），室间隔缺损41例（32.54%），动脉导管未闭11例（8.73%）。杂音组184例，单纯心脏杂音筛查检出率1.49%，灵敏度为82.5%，特异度为99.3%。经皮氧饱和度阳性组147例，单纯经皮氧饱和度阳性筛查检出率1.19%，灵敏度为58.7%，特异度为99.4%。双阳性组166例，两项指标联合筛查检出率1.35%，灵敏度为94.4%，特异度为99.6%。结论："双期三步法"筛查诊断流程特别是心脏听诊和经皮氧饱和度联合筛查有利于早期发现新生儿CHD，值得推广应用。     

阿魏酸钠对肺结核模型小鼠免疫功能及肺泡巨噬细胞吞噬功能的调控作用研究

摘要 目的：探讨与分析阿魏酸钠对肺结核模型小鼠免疫功能及肺泡巨噬细胞吞噬功能的调控作用。方法：肺结核模型小鼠(n=36)随机分为模型组、利福平组、阿魏酸钠组,每组各12只。利福平组、阿魏酸钠组分别给予100 mg/kg剂量的利福平与阿魏酸钠,模型组小鼠灌胃等量生理盐水,1次/d,给药6周,观察与记录所有小鼠的一般特征;分别于给药第2周、第4周、第6周,HE染色观察小鼠的病理特征;MDA检测试剂盒和总SOD活性检测试剂盒测定肺组织MDA水平与SOD活性;流式细胞仪检测小鼠T淋巴细胞亚群-CD3⁺T淋巴细胞、CD4⁺T淋巴细胞水平;酶联免疫法检测血清IL-6、IL-8含量;AnnexinV-FITC检测肺泡巨噬细胞凋亡率。结果：利福平组、阿魏酸钠组给药第2周、第4周、第6周的肺组织丙二醛（Malondialdehyde,MDA）水平低于模型组（P<0.05）,超氧化物岐化酶（superoxide dismutase,SOD）活性高于模型组（P<0.05）,利福平组与阿魏酸钠组对比也有明显差异（P<0.05）。利福平组、阿魏酸钠组给药第2周、第4周、第6周的血液CD3⁺T淋巴细胞、CD4⁺T淋巴细胞比例明显高于模型组（P<0.05）,阿魏酸钠组也高于利福平组（P<0.05）。利福平组、阿魏酸钠组给药第2周、第4周、第6周的血清IL-6、IL-8含量明显低于模型组（P<0.05）,阿魏酸钠组也低于利福平组（P<0.05）。利福平组、阿魏酸钠组给药第2周、第4周、第6周的肺泡灌洗液（broncho alveolar lavage fluid,BALF）巨噬细胞凋亡率明显低于模型组（P<0.05）,阿魏酸钠组也明显低于利福平组（P<0.05）。结论：阿魏酸钠在肺结核模型小鼠的应用可抑制炎症因子的表达,并改善氧化状况,还能增强小鼠的免疫功能,降低肺泡灌洗液巨噬细胞凋亡率。     

痰涂片标本用于结核分枝杆菌耐药性检测的研究

目的 研究抗酸染色结核分枝杆菌(简称结核杆菌)阳性痰涂片标本直接用于耐药性检测的方法。方法 对18株临床分离培养的结核杆菌用利福平进行药敏试验。分别提取菌株DNA和与之对应的痰涂片标本的菌体DNA,用聚合酶链反应(PcR)扩增ropB基因后进行固相杂交和核酸测序检测结核杆菌的耐药性。结果 18株结核杆菌中有12株对利福平耐药。经PCR扩增的ropB片段与探针杂交后,敏感菌株未发现rpoB基因的突变,自耐药菌株提取的DNA中rpoB突变体的检出率为100％(12／12),痰涂片提取DNA的检出率为91．7％(11／12)。所有耐药菌株DNA与痰涂片DNA核酸测序结果相吻合,都有rpoB基因核心区域碱基突变。结论 抗酸染色痰涂片阳性标本可直接用于检测结核杆菌利福平耐药基因rpoB突变体,是一种值得临床实验室推广使用的耐药菌诊断方法。     

HCMV-DNA定量检测和HCMV-IgG抗体AI检测在儿童HCMV感染诊断中的临床价值

摘要 目的：探讨人巨细胞病毒（HCMV）-DNA定量检测和HCMV-免疫球蛋白G（IgG）抗体亲和力指数（AI）检测在儿童HCMV感染诊断中的临床价值。方法：收集高度疑似HCMV活动性感染患儿血清样本103例作为研究组,健康体检儿童血清样本94例作为对照组。分析HCMV-DNA定量检测结果和HCMV-IgG抗体AI检测结果,并比较不同年龄、不同性别患儿HCMV-DNA阳性结果检出率和低HCMV-IgG抗体AI检出情况。结果：研究组血清HCMV-DNA阳性率为33.01%（34/103）,对照组血清HCMV-DNA均为阴性,研究组血清HCMV-DNA阳性率明显高于对照组,差异有统计学意义（P<0.05）。研究组血清低HCMV-IgG抗体AI检出率为13.59%（14/103）,对照组未检出低HCMV-IgG抗体AI,研究组血清低HCMV-IgG抗体AI检出率高于对照组,差异有统计学意义（P<0.05）。研究组不同性别之间患儿血清的HCMV-DNA阳性率、低HCMV-IgG抗体AI检测结果均无统计学差异（P>0.05）。研究组年龄1～5岁患儿血清HCMV-DNA阳性率明显低于年龄1 d～<6个月和年龄6个月～<1岁患儿（P<0.05）。三个年龄段患儿的血清低HCMV-IgG抗体AI检测结果均无统计学差异（P>0.05）。结论：1岁以下儿童更易受到HCMV感染,HCMV-DNA定量检测和HCMV-IgG抗体AI检测结果可以为临床早期诊断和治疗HCMV感染提供有效依据。     

冠状动脉CTA结合动态心电图夜间ST段趋势图诊断冠状动脉硬化性心脏病的价值研究

摘要 目的：探讨冠状动脉CTA结合动态心电图夜间ST段趋势图对冠状动脉硬化性心脏病（冠心病）的诊断价值。方法：回顾性分析2022年1月-2023年2月在我院疑似冠心病的患者104例,所有患者均行冠状动脉造影、冠状动脉CTA、动态心电图及临床相关实验室检查。以冠状动脉造影结果作为诊断冠心病的金标准,分析比较冠状动脉CTA、动态心电图夜间ST段趋势图及两者联合诊断冠心病的诊断效能和一致性。结果：104例疑似冠心病的患者确诊93例（89.42%）。冠状动脉CTA诊断冠心病的敏感性为90.32%,特异性为72.73%,阳性预测值为96.55%,阴性预测值为47.06%,准确率为88.46%,与冠状动脉造影的Kappa值为0.813,一致性好。动态心电图夜间ST段趋势图诊断冠心病的敏感性为84.95%,特异性为63.64%,阳性预测值为95.18%,阴性预测值为33.33%,准确率为82.69%,与冠状动脉造影的Kappa值为0.724,一致性较好。有夜间ST段动态改变的冠心病检出率（84.95%,79/93）明显高于无夜间ST段动态改变的冠心病检出率（15.05%,14/93）,差异有统计学意义（P＜0.001）。冠状动脉CTA结合动态心电图夜间ST段趋势图诊断冠心病的敏感性为96.77%,特异性为90.91%,阳性预测值为98.90%,阴性预测值为76.92%,准确率为96.15%,与冠状动脉造影的Kappa值为0.923,一致性好。结论：冠状动脉CTA结合动态心电图夜间ST段趋势图诊断冠心病的临床价值优于冠状动脉CTA或动态心电图夜间ST段趋势图单独检查。     

Evaluation of Xpert? MTB/RIF Assay in Induced Sputum and Gastric Lavage Samples from Young Children with Suspected Tuberculosis from the MVA85A TB Vaccine Trial

Objective

Diagnosis of childhood tuberculosis is limited by the paucibacillary respiratory samples obtained from young children with pulmonary disease. We aimed to compare accuracy of the Xpert^® MTB/RIF assay, an automated nucleic acid amplification test, between induced sputum and gastric lavage samples from young children in a tuberculosis endemic setting.

Methods

We analyzed standardized diagnostic data from HIV negative children younger than four years of age who were investigated for tuberculosis disease near Cape Town, South Africa [2009–2012]. Two paired, consecutive induced sputa and early morning gastric lavage samples were obtained from children with suspected tuberculosis. Samples underwent Mycobacterial Growth Indicator Tube [MGIT] culture and Xpert MTB/RIF assay. We compared diagnostic yield across samples using the two-sample test of proportions and McNemar’s χ² test; and Wilson’s score method to calculate sensitivity and specificity.

Results

1,020 children were evaluated for tuberculosis during 1,214 admission episodes. Not all children had 4 samples collected. 57 of 4,463[1.3%] and 26 of 4,606[0.6%] samples tested positive for Mycobacterium tuberculosis on MGIT culture and Xpert MTB/RIF assay respectively. 27 of 2,198[1.2%] and 40 of 2,183[1.8%] samples tested positive [on either Xpert MTB/RIF assay or MGIT culture] on induced sputum and gastric lavage samples, respectively. 19/1,028[1.8%] and 33/1,017[3.2%] admission episodes yielded a positive MGIT culture or Xpert MTB/RIF assay from induced sputum and gastric lavage, respectively. Sensitivity of Xpert MTB/RIF assay was 8/30[26.7%; 95% CI: 14.2–44.4] for two induced sputum samples and 7/31[22.6%; 11.4–39.8] [p = 0.711] for two gastric lavage samples. Corresponding specificity was 893/893[100%;99.6–100] and 885/890[99.4%;98.7–99.8] respectively [p = 0.025].

Conclusion

Sensitivity of Xpert MTB/RIF assay was low, compared to MGIT culture, but diagnostic performance of Xpert MTB/RIF did not differ sufficiently between induced sputum and gastric lavage to justify selection of one sampling method over the other, in young children with suspected pulmonary TB.

Trial Registration

ClinicalTrials.gov NCT00953927     

Catching the Missing Million: Experiences in Enhancing TB & DR-TB Detection by Providing Upfront Xpert MTB/RIF Testing for People Living with HIV in India

BackgroundA critical challenge in providing TB care to People Living with HIV (PLHIV) is establishing an accurate bacteriological diagnosis. Xpert MTB/RIF, a highly sensitive and specific rapid tool, offers a promising solution in addressing these challenges. This study presents results from PLHIV taking part in a large demonstration study across India wherein upfront Xpert MTB/RIF testing was offered to all presumptive PTB cases in public health facilities.MethodThe study covered a population of 8.8 million across 18 sub-district level tuberculosis units (TU), with one Xpert MTB/RIF platform established at each TU. All HIV-infected patients suspected of TB (both TB and Drug Resistant TB (DR-TB)) accessing public health facilities in study area were prospectively enrolled and provided upfront Xpert MTB/RIF testing.Result2,787 HIV-infected presumptive pulmonary TB cases were enrolled and 867 (31.1%, 95% Confidence Interval (CI) 29.4‒32.8) HIV-infected TB cases were diagnosed under the study. Overall 27.6% (CI 25.9–29.3) of HIV-infected presumptive PTB cases were positive by Xpert MTB/RIF, compared with 12.9% (CI 11.6–14.1) who had positive sputum smears. Upfront Xpert MTB/RIF testing of presumptive PTB and DR-TB cases resulted in diagnosis of 73 (9.5%, CI 7.6‒11.8) and 16 (11.2%, CI 6.7‒17.1) rifampicin resistance cases, respectively. Positive predictive value (PPV) for rifampicin resistance detection was high 97.7% (CI 89.3‒99.8), with no significant difference with or without prior history of TB treatment.ConclusionThe study results strongly demonstrate limitations of using smear microscopy for TB diagnosis in PLHIV, leading to low TB and DR-TB detection which can potentially lead to either delayed or sub-optimal TB treatment. Our findings demonstrate the usefulness and feasibility of addressing this diagnostic gap with upfront of Xpert MTB/RIF testing, leading to overall strengthening of care and support package for PLHIV.     

Use of Xpert MTB/RIF in Decentralized Public Health Settings and Its Effect on Pulmonary TB and DR-TB Case Finding in India

BackgroundXpert MTB/RIF, the first automated molecular test for tuberculosis, is transforming the diagnostic landscape in high-burden settings. This study assessed the impact of up-front Xpert MTB/RIF testing on detection of pulmonary tuberculosis (PTB) and rifampicin-resistant PTB (DR-TB) cases in India.MethodsThis demonstration study was implemented in 18 sub-district level TB programme units (TUs) in India in diverse geographic and demographic settings covering a population of 8.8 million. A baseline phase in 14 TUs captured programmatic baseline data, and an intervention phase in 18 TUs had Xpert MTB/RIF offered to all presumptive TB patients. We estimated changes in detection of TB and DR-TB, the former using binomial regression models to adjust for clustering and covariates.ResultsIn the 14 study TUs, which participated in both phases, 10,675 and 70,556 presumptive TB patients were enrolled in the baseline and intervention phase, respectively, and 1,532 (14.4%) and 14,299 (20.3%) bacteriologically confirmed PTB cases were detected. The implementation of Xpert MTB/RIF was associated with increases in both notification rates of bacteriologically confirmed TB cases (adjusted incidence rate ratio [aIRR] 1.39; CI 1.18-1.64), and proportion of bacteriological confirmed TB cases among presumptive TB cases (adjusted risk ratio (aRR) 1.33; CI 1.6-1.52). Compared with the baseline strategy of selective drug-susceptibility testing only for PTB cases at high risk of drug-resistant TB, Xpert MTB/RIF implementation increased rifampicin resistant TB case detection by over fivefold. Among, 2765 rifampicin resistance cases detected, 1055 were retested with conventional drug susceptibility testing (DST). Positive predictive value (PPV) of rifampicin resistance detected by Xpert MTB/RIF was 94.7% (CI 91.3-98.1), in comparison to conventional DST.ConclusionIntroduction of Xpert MTB/RIF as initial diagnostic test for TB in public health facilities significantly increased case-notification rates of all bacteriologically confirmed TB by 39% and rifampicin-resistant TB case notification by fivefold.     

Comparative analysis of TB-Biochip, Xpert MTB/RIF, and GenoType MTBDRplus test systems for rapid determination of mutations responsible for drug resistance of M. tuberculosis complex (in sputum from patients in Moscow region)

We studied the frequency of occurrence and combinations of mutations in rpoB, katG, inhA, and oxyR-ahpC genes of Mycobacterium tuberculosis (MTB) DNA isolated from patients of Moscow region. In isoniazid monoresistant MTB isolates, Ser315Thr mutation in the katG gene prevails (15.8%), whereas the most frequent mutations in multidrug-resistant MTB isolates were Ser531Leu in the rpoB gene, Ser315Thr in the katG gene (26.3%), and their combination with C(-15)T in the inhA gene (5.3%). The efficiency of TB-Biochip (OOO Biochip-IMB Russia), Xpert MTB/RIF (Cepheid, United States), and GenoType MTBDRplus (Hain Lifescience, Germany) test systems was analyzed and compared with the efficiency of luminescent microscopy and phenotypic drug-susceptibility testing in BACTEC? MGIT? 960 automated system (Becton, Dickinson and Company, United States). Using Xpert MTB/RIF, TB-Biochip, and GenoType MTBDRplus systems, MTB DNA was detected in sputum from patients in 92, 78, and 49% of all culturepositive cases, respectively. Standard cultural data match the test results of the susceptibility of MTB for Xpert MTB/RIF (rifampicin resistance) and for TB-Biochip and GenoType MTBDRplus (resistance to rifampicin and isoniazid) by 100, 97, and 100%, respectively. Thus, Xpert MTB/RIF system is the most efficient in primary MTB DNA detection, and TB-Biochip is the only one sensitive enough for both MTB DNA detection and determination of MTB multidrug resistance in sputum. Multidrug resistance is considered as resistance to both rifampicin and isoniazid.     

Diagnostic Accuracy and Turnaround Time of the Xpert MTB/RIF Assay in Routine Clinical Practice

The Xpert MTB/RIF assay was introduced for timely and accurate detection of tuberculosis (TB). The aim of this study was to determine the diagnostic accuracy and turnaround time (TAT) of Xpert MTB/RIF assay in clinical practice in South Korea. We retrospectively reviewed the medical records of patients in whom Xpert MTB/RIF assay using sputum were requested. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of pulmonary tuberculosis (PTB) and detection of rifampicin resistance were calculated. In addition, TAT of Xpert MTB/RIF assay was compared with those of other tests. Total 681 patients in whom Xpert MTB/RIF assay was requested were included in the analysis. The sensitivity, specificity, PPV and NPV of Xpert MTB/RIF assay for diagnosis of PTB were 79.5% (124/156), 100.0% (505/505), 100.0% (124/124) and 94.0% (505/537), respectively. Those for the detection of rifampicin resistance were 57.1% (8/14), 100.0% (113/113), 100.0% (8/8) and 94.9% (113/119), respectively. The median TAT of Xpert MTB/RIF assay to the report of results and results confirmed by physicians in outpatient settings were 0 (0–1) and 6 (3–7) days, respectively. Median time to treatment after initial evaluation was 7 (4–9) days in patients with Xpert MTB/RIF assay, but was 21 (7–33.5) days in patients without Xpert MTB/RIF assay. Xpert MTB/RIF assay showed acceptable sensitivity and excellent specificity for the diagnosis of PTB and detection of rifampicin resistance in areas with intermediate TB burden. Additionally, the assay decreased time to the initiation of anti-TB drugs through shorter TAT.     

Performance Characteristics of the Cepheid Xpert MTB/RIF Test in a Tuberculosis Prevalence Survey

Background

Xpert MTB/RIF (“Xpert”) is a molecular test for detection of Mycobacterium tuberculosis (MTB) in sputum. Performance characteristics have been established for its use during passive tuberculosis (TB) case detection in symptomatic TB suspects, but Xpert performance has not been assessed in other settings. Objectives were to determine Xpert performance and costs in the context of a TB prevalence survey.

Methodology/Principal Findings

This was a diagnostic sub-study of a TB prevalence survey conducted in gold mining companies in South Africa. Sputa (one per participant) were tested using smear microscopy, liquid culture (reference comparator), and Xpert. Costs were collected using an ingredients approach and analyzed using a public health program perspective. 6893 participants provided a sputum specimen. 187/6893 (2.7%) were positive for MTB in culture, 144/6893 (2.1%) were positive for MTB by Xpert, and 91/6893 (1.3%) were positive for acid fast bacilli by microsocopy. Sensitivity, specificity, positive predictive value, and negative predictive value for detection of MTB by Xpert were 62.6% (95% confidence interval [CI] 55.2, 69.5), 99.6% (99.4, 99.7), 81.3% (73.9, 87.3), and 98.9 (98.6, 98.8); agreement between Xpert and culture was 98.5% (98.2, 98.8). Sensitivity of microscopy was 17.6% (12.5, 23.9). When individuals with a history of TB treatment were excluded from the analysis, Xpert specificity was 99.8 (99.7, 99.9) and PPV was 90.6 (83.3, 95.4) for detection of MTB. For the testing scenario of 7000 specimens with 2.7% of specimens culture positive for MTB, costs were $165,690 for Xpert and $115,360 for the package of microscopy plus culture.

Conclusion

In the context of a TB prevalence survey, the Xpert diagnostic yield was substantially higher than that of microscopy yet lower than that of liquid culture. Xpert may be useful as a sole test for TB case detection in prevalence surveys, particularly in settings lacking capacity for liquid culture.     

Evaluating the Diagnostic Accuracy of Xpert MTB/RIF Assay in Pulmonary Tuberculosis

Pulmonary tuberculosis still remains a major communicable disease worldwide. In 2013, 9 million people developed TB and 1.5 million people died from the disease. India constitutes 24% of the total TB burden. Early detection of TB cases is the key to successful treatment and reduction of disease transmission. Xpert MTB/RIF, an automated cartridge-based molecular technique detects Mycobacterium tuberculosis and rifampicin resistance within two hours has been endorsed by WHO for rapid diagnosis of TB. Our study is the first study from India with a large sample size to evaluate the performance of Xpert MTB/RIF assay in PTB samples. The test showed an overall sensitivity and specificity of 95.7% (430/449) and 99.3% (984/990) respectively. In smear negative-culture positive cases, the test had a sensitivity of 77.7%. The sensitivity and specificity for detecting rifampicin resistance was 94.5% and 97.7% respectively with respect to culture as reference standard. However, after resolving the discrepant samples with gene sequencing, the sensitivity and specificity rose to 99.0% and 99.3% respectively. Hence, while solid culture still forms the foundation of TB diagnosis, Xpert MTB/RIF proposes to be a strong first line diagnostic tool for pulmonary TB cases.     

Comparison of Xpert MTB/RIF with other nucleic acid technologies for diagnosing pulmonary tuberculosis in a high HIV prevalence setting: a prospective study

Background

The Xpert MTB/RIF (Cepheid) non-laboratory-based molecular assay has potential to improve the diagnosis of tuberculosis (TB), especially in HIV-infected populations, through increased sensitivity, reduced turnaround time (2 h), and immediate identification of rifampicin (RIF) resistance. In a prospective clinical validation study we compared the performance of Xpert MTB/RIF, MTBDRplus (Hain Lifescience), LightCycler Mycobacterium Detection (LCTB) (Roche), with acid fast bacilli (AFB) smear microscopy and liquid culture on a single sputum specimen.

Methods and Findings

Consecutive adults with suspected TB attending a primary health care clinic in Johannesburg, South Africa, were prospectively enrolled and evaluated for TB according to the guidelines of the National TB Control Programme, including assessment for smear-negative TB by chest X-ray, clinical evaluation, and HIV testing. A single sputum sample underwent routine decontamination, AFB smear microscopy, liquid culture, and phenotypic drug susceptibility testing. Residual sample was batched for molecular testing. For the 311 participants, the HIV prevalence was 70% (n = 215), with 120 (38.5%) culture-positive TB cases. Compared to liquid culture, the sensitivities of all the test methodologies, determined with a limited and potentially underpowered sample size (n = 177), were 59% (47%–71%) for smear microscopy, 76% (64%–85%) for MTBDRplus, 76% (64%–85%) for LCTB, and 86% (76%–93%) for Xpert MTB/RIF, with specificities all >97%. Among HIV+ individuals, the sensitivity of the Xpert MTB/RIF test was 84% (69%–93%), while the other molecular tests had sensitivities reduced by 6%. TB detection among smear-negative, culture-positive samples was 28% (5/18) for MTBDRplus, 22% (4/18) for LCTB, and 61% (11/18) for Xpert MTB/RIF. A few (n = 5) RIF-resistant cases were detected using the phenotypic drug susceptibility testing methodology. Xpert MTB/RIF detected four of these five cases (fifth case not tested) and two additional phenotypically sensitive cases.

Conclusions

The Xpert MTB/RIF test has superior performance for rapid diagnosis of Mycobacterium tuberculosis over existing AFB smear microscopy and other molecular methodologies in an HIV- and TB-endemic region. Its place in the clinical diagnostic algorithm in national health programs needs exploration. Please see later in the article for the Editors'' Summary     

Enhancing TB Case Detection: Experience in Offering Upfront Xpert MTB/RIF Testing to Pediatric Presumptive TB and DR TB Cases for Early Rapid Diagnosis of Drug Sensitive and Drug Resistant TB

Background

Diagnosis of pulmonary tuberculosis (PTB) in children is challenging due to difficulties in obtaining good quality sputum specimens as well as the paucibacillary nature of disease. Globally a large proportion of pediatric tuberculosis (TB) cases are diagnosed based only on clinical findings. Xpert MTB/RIF, a highly sensitive and specific rapid tool, offers a promising solution in addressing these challenges. This study presents the results from pediatric groups taking part in a large demonstration study wherein Xpert MTB/RIF testing replaced smear microscopy for all presumptive PTB cases in public health facilities across India.

Methods

The study covered a population of 8.8 million across 18 programmatic sub-district level tuberculosis units (TU), with one Xpert MTB/RIF platform established at each study TU. Pediatric presumptive PTB cases (both TB and Drug Resistant TB (DR-TB)) accessing any public health facilities in study area were prospectively enrolled and tested on Xpert MTB/RIF following a standardized diagnostic algorithm.

Results

4,600 pediatric presumptive pulmonary TB cases were enrolled. 590 (12.8%, CI 11.8–13.8) pediatric PTB were diagnosed. Overall 10.4% (CI 9.5–11.2) of presumptive PTB cases had positive results by Xpert MTB/RIF, compared with 4.8% (CI 4.2–5.4) who had smear-positive results. Upfront Xpert MTB/RIF testing of presumptive PTB and presumptive DR-TB cases resulted in diagnosis of 79 and 12 rifampicin resistance cases, respectively. Positive predictive value (PPV) for rifampicin resistance detection was high (98%, CI 90.1–99.9), with no statistically significant variation with respect to past history of treatment.

Conclusion

Upfront access to Xpert MTB/RIF testing in pediatric presumptive PTB cases was associated with a two-fold increase in bacteriologically-confirmed PTB, and increased detection of rifampicin-resistant TB cases under routine operational conditions across India. These results suggest that routine Xpert MTB/RIF testing is a promising solution to present-day challenges in the diagnosis of PTB in pediatric patients.