γ干扰素释放试验在结核病诊断中的应用价值

目的分析γ干扰素释放试验(IGRA)在结核病诊断中的应用价值。方法收集2017年11月-2019年1月广州南方医院796例进行IGRA检测的住院患者资料,分析IGRA对结核病的诊断价值,并将其与痰涂片抗酸染色镜检、结核抗体胶体金法、结核分枝杆菌DNA荧光定量PCR法、结核菌素皮肤试验(TST)、结核分枝杆菌感染T细胞斑点试验(T-SPOT.TB)进行比较。结果 IGRA对肺结核和肺外结核检出阳性率分别为80.2%和84.1%,差异无统计学意义(P>0.05);肺结核组与非结核组阳性率差异有显著统计学意义(P<0.01)。IGRA对结核诊断的灵敏度、特异度、阳性预测值和阴性预测值分别为 81.9%、81.3%、60.1%和92.9%。痰涂片抗酸染色镜检、结核抗体胶体金法、结核分枝杆菌DNA荧光定量PCR法、TST、T-SPOT.TB的灵敏度分别为3.4%、21.1%、15.2%、66.7%、82.9%。结论 IGRA灵敏度和阴性预测值较好,对结核辅助诊断具有较高临床应用价值。     

两种结核抗原特异性干扰素释放试验试剂用于HIV感染人群中结核潜伏感染诊断的比较

目的 比较评价自行研发及国外进口T-SPOT TB两种结核抗原特异性γ干扰素释放试验在HIV感染人群中诊断结核潜伏感染的价值.方法 102例HIV感染者均来自于深圳市第三人民医院艾滋病门诊,其中男66例,女36例,平均年龄35岁.运用自行研发的结核杆菌抗原特异性γ干扰素ELISpot检测方法及T-SPOT TB试剂盒对102例确诊的HIV感染者的外周血结核特异性γ干扰素释放水平进行检测,并同时进行TST.结果 在HIV感染者中17例患者T-SPOT和ELISpot两种方法检测共同阳性,ELISpot的敏感度、特异度、阳性预测值、阴性预测值和准确性分别为94.4%、94.0%、77.3%、98.8%和94.1%.其中3例患者在TST与T-SPOT两种检验方法检测共同阳性,TST的敏感度、特异度、阳性预测值、阴性预测值和准确性分别为16.7%、98.8%、75.0%、84.7%和84.3%.利用3种抗原对102例患者进行检测,结核分枝杆菌重组抗原(ESAT-6)、PoolA、PoolB刺激所得斑点数的平均值分别为26.89±5.77、18.96±4.75和14.51±3.77,仅ESAT-6与PoolB的差异有统计学意义(H=7.557,P=0.022 9).不同CD4分组ELISpot检测阳性率和T-SPOT TB检测阳性率差异均无统计学意义(x2=0.860 8,P=0.650 2;x2=1.396 4,P=0.497 5).结论 自行研发的结核杆菌抗原特异性γ干扰素ELISpot检测技术在HIV感染人群中用于结核潜伏感染的诊断与T-SPOT TB检测方法类似,两种方法的敏感度与特异度均高于TST,可用于艾滋病合并结核潜伏感染的辅助诊断.

Abstract：

Objective To evaluate the diagnostic value of two tuberculosis-specific IFN-γ release assays in latent tuberculosis infection among HIV-infected individuals. Methods The levels of tuberculosis antigen-specific IFN-γin 102 HIV patients from AIDS Outpatient Clinic of Shenzhen Third People's Hospital were detected by in-house tuberculosis-specific IFN-γ ELISpot assay and commercial T-SPOT TB kit, and tuberculin skin test (TST) were done at the same time. There were 66 males and 36 females,and the average age was 35. Results Seventeen HIV infected patients were positive in both IFN-γ ELISpot and T-SPOT TB methods, the sensitivity, specificity positive predictive value(PPV), negative predictive value(NPV) and compliance rates of ELISpot were 94. 4% ,94. 0% ,77. 3% ,98. 8% and 94. 1% ,respectively. Three patients were positive in both IFN-γELISpot and T-SPOT TB methods, the sensitivity, specificity, PPV, NPV and compliance rates of TST were 16. 7%, 98. 8%, 75.0%, 84. 7% and 84. 3%, respectively. The average number of spots using three kinds of antigen ESAT-6, Pool A,Pool B obtained were 26. 89 ±5. 77,18. 96 ±4. 75 and 14. 51 ± 3.77, respectively. Only ESAT-6 and Pool B have a statistically significant difference (H=7.557,P = 0.022 9), no significant difference was shown between other groups. There was no significant difference between the positive rate and the CD4+ T cellls number(x2 =0. 860 8 ,P =0. 650 2) ,as the same as the T-SPOT TB (x2 = 1. 396 4, P = 0. 497 5 ). Conclusions The performance of this in-house tuberculosis-specific IFN-γ ELISPot assay was comparable to T-SPOT assay in diagnosis of latent tuberculosis infection, and the sensitivity and specificity of both these two assays were all much higher than TST. They canbe recommended in diagnosing latent tuberculosis infection in HIV infected patients.     

不同诊断技术用于肺外结核病辅助诊断的临床价值比较

目的比较结核菌素试验(TST)和结核感染T细胞斑点试验(T-SPOT.TB)用于肺外结核病(EPTB)辅助诊断的临床价值。方法回顾性分析南通市如东县中医院2017年1月至2019年5月收治的行TST和T-SPOT.TB检测的EPTB患者(64例,EPTB组)和非结核性疾病患者(106例,对照组)的临床资料,比较两种检测技术诊断的灵敏度、特异度、阳性预测值及阴性预测值,并行ROC曲线分析两种方法的诊断效能。结果T-SPOT.TB辅助诊断EPTB的灵敏度、特异度、阳性预测值及阴性预测值均明显优于TST(P<0.05);ROC曲线分析显示,TST和T-SPOT.TB辅助诊断EPTB曲线下面积分别为0.633(95%CI:0.501~0.749)、0.892(95%CI:0.812~0.974)。结论T-SPOT.TB用于EPTB辅助诊断的灵敏度与特异度高,诊断效能佳,临床应用价值优于TST。     

外周血T-SPOT.TB试验对婴幼儿结核病的诊断价值

[目的]评价结核感染T细胞斑点试验(T-SPOT.TB)在诊断婴幼儿结核病(TB)中的临床应用价值.[方法]对2013年2月至2015年9月于本院就诊的118例3岁以内呼吸系统感染性疾病患儿行T-SPOT.TB、结核菌素试验(TST)和结核抗体(TB-Ab IgG)检测试验,比较这三种方法对TB诊断的特异性和灵敏度,评价应用T-SPOT.TB诊断活动性结核的价值.[结果]根据临床诊断标准,最终纳入婴幼儿结核感染组58例及非TB患儿对照组60例.T-SPOT.TB法诊断婴幼儿结核的敏感性和特异性分别为89.6％和93.3％,均高于TST(83.6％和66.7％)和TB-Ab IgG(65.5％和68.3％)检查,差异具有统计学意义(P＜0.05).T-SPOT.TB的阳性预测值和阴性预测值也分别高于TST和TB-Ab IgG检测.[结论]外周血T-SPOT.TB对诊断婴幼儿结核具有较高的灵敏度和特异度,对婴幼儿结核感染的准确快速诊断具有重要的参考价值.     

T细胞斑点试验AB抗原检测结果对结核感染患者诊断意义探讨

目的探讨结核感染T细胞斑点试验(T-SPOT.TB)中AB两种抗原检测结果在临床结核感染患者诊断中的意义。方法选取2013年6~11月住院治疗并最终确诊活动性结核的96例患者为研究对象,采集其外周血进行T-SPOT.TB检测,将检测结果与结核菌素试验(PPD)及最终诊断结果进行对比,并对AB两种抗原检出结果的一致性及其阳性斑点分布特点进行分析。结果 T-SPOT.TB灵敏度为97.9%,特异度为87.8%,准确度为94.5%,阳性预测值(PPV)为94.0%,阴性预测值(NPV)为95.6%,均显著高于PPD检测结果(P0.01)。T-SPOT.TB两种抗原A和B对检测结果阳性率无统计差异,阳性斑点分布特征分析显示抗原A阳性斑点数与结核活动性呈正相关趋势,有较高的特异度;而抗原B则分别在高、低阳性斑点区呈现活动性结核检出的高峰,具有更好的敏感度。结论 T-SPOT.TB试验对活动性结核诊断有高度的敏感度和特异度,且AB两种抗原表现出不同的阳性检出规律和意义。T-SPOT.TB试验可为临床结核病的筛查和大规模流行病学调查提供新的技术分析手段。     

γ-干扰素释放试验对筛查藏族肺结核患者的临床应用价值

目的比较γ-干扰素释放试验(IGRA)在藏族和汉族肺结核人群中的灵敏度和特异度,并探讨其对筛查藏族肺结核患者的临床应用价值。方法选取2013年4月至2015年4月藏族肺结核患者64例,藏族非肺结核患者41例,汉族肺结核患者40例,汉族非肺结核患者38例,行IGRA,以酶联免疫吸附法检测结核分枝杆菌感染T细胞,比较藏汉两族的差异性,并通过计算统计学指标评价IGRA对筛查藏族肺结核患者的临床价值。结果 IGRA对藏族肺结核的诊断灵敏度为90.62%(58/64),特异度为80.49%(33/41),阳性预测值为87.88%(58/66),阴性预测值为84.62%(33/39)。IGRAs对汉族肺结核的诊断灵敏度为92.50%(37/40),特异度为84.21%(32/38),阳性预测值为86.05%(37/43),阴性预测值为91.43%(32/35)。IGRAs对藏汉族肺结核诊断灵敏度差异无统计学意义(χ~2=0.005,P=0.944),IGRA对藏汉族肺结核诊断特异度差异无统计学意义(χ~2=0.018,P=0.893)。结论 IGRA对藏族肺结核的早期诊断价值较高,有利于对早期肺结核的筛查。     

Diagnostic performance of whole-blood interferon-γ assay and enzyme-linked immunospot assay for active tuberculosis'

The aim of this study was to compare the diagnostic performance of 2 interferon-γ release assays, an enzyme-linked immunospot assay (T-SPOT.TB; Oxford Immunotec Ltd., Oxford, UK) and the QuantiFERON-TB Gold in-Tube assay (QFT-GIT; Cellestis Ltd., Carnegie, Australia), in patients with suspected active tuberculosis (TB). From October 2009 to October 2011, a total of 200 patients with suspected TB were enrolled. Clinical and microbiological characteristics of the patients were collected and blood samples were obtained for T-SPOT.TB and QFT-GIT assays. Among the 200 subjects, 98 (49%) had culture-confirmed TB, 18 (9%) had probable TB, and the remaining 84 (42%) subjects did not have TB. The sensitivity, specificity, positive predictive value, and negative predictive value for active TB diagnosis by the T SPOT. TB were 83%, 71%, 81%, and 75%, respectively. For QFT-GIT, the sensitivity, specificity, positive predictive value, and negative predictive value for active TB diagnosis were 66%, 76%, 80%, and 62%, respectively. The QFT-GIT assay resulted in more indeterminate and false-negative results than the T-SPOT.TB assay, especially in immunocompromised patients. In conclusion, T-SPOT.TB had a higher sensitivity and resulted in fewer indeterminate results than the QFT-GIT assay for diagnosing active TB.     

Comparison of an in-house and a commercial RD1-based ELISPOT-IFN-gamma assay for the diagnosis of Mycobacterium tuberculosis infection

OBJECTIVE: To compare a RD1-based in-house ELISPOT-interferon-gamma (IFN-gamma) assay with a commercial (T-SPOT.TB) assay for the diagnosis of Mycobacterium tuberculosis (TB) infection and the efficacy of the tuberculin skin test (TST) and ELISPOT assay in detecting latent TB infection (LTBI). DESIGN: Eighty-six subjects (65 household contacts of contagious TB-infected patients, 13 subjects with active or previous TB infection, and 8 with suspected TB infection) were consecutively recruited in the context of a surveillance program. METHODS: Enrolled subjects underwent the Mantoux TST and two different ELISPOT-IFN-gamma assays: an in-house assay using a pool of selected M. tuberculosis peptides (MTP) and the commercial T-SPOT.TB assay. RESULTS: The in-house and commercial ELISPOT-IFN-gamma assays showed almost complete concordance (99%) in diagnosing acute or LTBI.When comparing the efficacy of the TST with the in-house ELISPOT assay in detecting TB infection, a small agreement was observed (k=0.344, P<0.0001): 36% of the subjects with a positive TST were ELISPOT-MTP negative and 12% with a negative TST were ELISPOT-MTP positive. Furthermore, 78% of the ELISPOT-MTP negative individuals were ELISPOT- Bacillus Calmette-Guérin (BCG) positive, most of whom had received BCG vaccination. CONCLUSION: Our in-house ELISPOT assay based on a restricted pool of highly selected peptides is equivalent to the commercial T-SPOT.TB assay, is cheaper and is probably not confounded, unlike the TST, by BCG vaccination in our setting.     

QuantiFERON-TB Gold and selected region of difference 1 peptide-based assays for the detection of Mycobacterium tuberculosis infection in a cohort of patients enrolled with suspected tuberculosis

Recently, a simple whole blood test, QuantiFERON-TB Gold (QFT-Gold), has been adopted for immunologic diagnosis of Mycobacterium tuberculosis infection. A total of 369 individuals with suspected tuberculosis (TB) were tested with the QFT-Gold, whereas a subgroup of 62 patients was tested simultaneously with QFT-Gold test and an assay based on selected peptides from early secreted antigenic target 6 and culture filtrate protein 10 proteins. The sensitivity of the QFT-Gold assay for active TB was 72.9%, and the agreement between this test and tuberculin skin test was 75%. Using selected peptides, we found a positive response in the majority of active TB patients, with a sensitivity of 84% and a specificity of 89%. Our study suggests the usefulness of QFT-Gold in routine clinical practice on unselected patients with suspected TB. Moreover, the assay based on selected peptides is a useful tool to discriminate between active and latent TB and shows a high predictive value.     

Comparison of interferon gamma-inducible protein-10 and interferon gamma-based QuantiFERON TB Gold assays with tuberculin skin test in HIV-infected subjects

We aimed to compare the positivity of the QuantiFERON TB gold in-tube (QFT-IT antigens) specific interferon gamma (IFN-γ/QFT-IT) and IFN-γ–inducible protein-10 (IP-10/QFT-IT) assays with tuberculin skin test (TST) among human immunodeficiency virus (HIV)–infected individuals in a TB endemic setting. A total of 180 HIV-infected subjects, with no evidence of active TB, were recruited. IFN-γ and IP-10 levels specific to QFT-IT antigens were measured in plasma from QFT-IT tubes. The overall positivity of TST at the 5-mm cut-off point (19%) was significantly lower when compared to IFN-γ/QFT-IT (38%) and IP-10/QFT-IT (45%) assays. The positivity of IP-10/QFT-IT was significantly higher than that of IFN-γ/QFT-IT (P = 0.038). Indeterminate results for IFN-γ/QFT-IT and IP-10/QFT-IT were more frequent in subjects with CD4 count <100 cells/μL than in those with >100 cells/μL. IFN-γ/QFT-IT (9%) yielded significantly higher number of indeterminate results than IP-10/QFT-IT (5%). The frequency of these responses is higher than the proportion of individuals with positive TST results. However, 6 IFN-γ/QFT-IT– or IP-10/QFT-IT–negative subjects were positive for TST at the 5-mm cut-off point. Prospective and prognostic studies are required to clarify the significance of these data.     

Diagnostic value of an enzyme-linked immunospot assay for interferon-γ in genitourinary tuberculosis

The aim of this study was to evaluate the diagnostic performance of an enzyme-linked immunospot (ELISPOT) assay for interferon-γ in patients with suspected genitourinary tuberculosis (TB). A total of 30 patients with suspected genitourinary TB at the National Taiwan University Hospital, Taipei, Taiwan, were prospectively enrolled from January 2007 to December 2009, and 12 of whom had positive urine culture for Mycobacterium tuberculosis. Frequency and dysuria were the most common symptoms noted in 6 (50.0%) and 4 (33.3%) patients, respectively. Pyuria was the most common finding of urinalysis noted in 11 (91.7%) patients. Six (50.0%) patients had positive acid-fast stain in urine. Among the 30 patients, 13 patients had positive ELISPOT assay. Eleven patients with positive ELISPOT assay had culture-confirmed TB, and the remaining 2 patients without evidence of active TB had positive ELISPOT assay. The overall sensitivity, specificity, positive predictive value, and negative predictive value for genitourinary TB diagnosis by the ELISPOT assay were 91.7% (95% confidence interval [CI], 59.8–99.6%), 88.9% (95% CI, 63.9–98.1%), 84.6% (95% CI, 53.7–97.3%), and 94.1% (95% CI, 69.2–96.7%), respectively. In conclusion, ELISPOT assay can provide useful support in diagnosing genitourinary TB.     

Comparison of tuberculin skin test and a specific T-cell-based test, T-Spot.TB, for the diagnosis of latent tuberculosis infection

There is substantial evidence that the detection of T cells specific for the proteins ESAT-6 and CFP-10 using the ex vivo enzyme-linked immunospot technique is a marked improvement on the existing tuberculin skin test (TST). This new technique, which detects gamma-interferon-producing T cells, is now available as the commercial assay, T-Spot.TB. We compared the T-Spot.TB test with the TST for the diagnosis of latent tuberculosis infection (LTBI) in different groups of subjects. Significant accordance (85.7%) between the tests was found in subjects with active lung tuberculosis and in tuberculosis clinic and laboratory personnel (63.6%) but accordance was lowest and not significant amongst house contacts of tuberculosis patients (53.6%). We conclude that, in countries where vaccination is routinely performed, the T-Spot.TB test is a useful diagnostic test for LTBI in high-risk groups when carried out either together with the TST and/or to confirm the TST result.     

New tools and emerging technologies for the diagnosis of tuberculosis: part I. Latent tuberculosis

Nearly a third of the world's population is estimated to be infected with Mycobacterium tuberculosis. This enormous pool of latently infected individuals poses a major hurdle for global tuberculosis (TB) control. Currently, diagnosis of latent TB infection (LTBI) relies on the tuberculin skin test (TST), a century-old test with known limitations. In this review, the first of a two-part series on new tools for TB diagnosis, recent advances in the diagnosis of LTBI are described. The biggest advance in recent years has been the development of in vitro T-cell-based interferon-gamma release assays (IGRAs) that use antigens more specific to M. tuberculosis than the purified protein derivative used in the TST. Available research evidence on IGRAs suggests they have higher specificity than TST, better correlation with surrogate markers of exposure to M. tuberculosis in low-incidence settings, and less cross-reactivity due to BCG vaccination than the TST. IGRAs also appear to be at least as sensitive as the purified protein derivative-based TST for active TB. In the absence of a gold standard for LTBI, sensitivity and specificity for LTBI are not well defined. Besides high specificity, other potential advantages of IGRAs include logistical convenience, avoidance of poorly reproducible measurements, such as skin induration, need for fewer patient visits and the ability to perform serial testing without inducing the boosting phenomenon. Overall, due to its high specificity, IGRAs may be useful in low-endemic, high-income settings where cross-reactivity due to BCG might adversely impact the utility of TST. However, despite the growing evidence supporting the use of IGRAs, several unresolved and unexplained issues remain. The review concludes by highlighting areas where evidence is lacking, and provides an agenda for future research. Active TB and drug resistance are discussed in Part II; 423-432 of this issue.     

酶联免疫斑点技术在老年脊柱结核感染辅助诊断中的应用价值

【目的】评价酶联免疫斑点技术（ELISPOT ）在老年脊柱结核感染辅助诊断中的应用价值。【方法】选取2013年1月至2015年1月本院脊柱外科收治的疑似脊柱结核的老年患者56例,比较 ELISPOT试验、结核菌素（PPD）皮肤试验、血清抗结核抗体检测方法在老年脊柱结核感染辅助诊断中的敏感性、特异性、阳性预测值和阴性预测值。【结果】ELISPOT 试验在脊柱结核诊断中的敏感性、特异性、阳性预测值和阴性预测值分别为77．14％,85．71％,90．00％,69．23％;PPD 皮肤试验的敏感性、特异性、阳性预测值和阴性预测值分别为37．14％,71．43％,68．42％,40．54％;血清抗结核抗体试验的敏感性、特异性、阳性预测值和阴性预测值分别为48．57％,61．90％,68．00％,61．90％。在老年脊柱结核患者中,ELISPOT 试验的敏感性、特异性、阳性预测值均显著高于 PPD 皮肤试验和血清抗结核抗体试验。【结论】ELISPOT 法应用于老年脊柱结核诊断有良好的敏感性和特异性,可作为脊柱结核感染辅助诊断的有效方法。     

γ-干扰素释放试验对肺结核与肺外结核诊断的敏感性和特异性观察

目的 探讨肺结核与肺外结核γ-干扰素释放试验(IGRAs)在肺结核和肺外结核诊断中的应用价值。方法 选择该院2014年7月至2015年7月住院结核病疑似病例217例,常规进行相关检测及IGRAs试验,所有患者随访3个月,根据结核诊断依据分为2组,结核确诊和临床诊断组81例,无结核证据组136例,观察IGRAs试验结果。结果IGRAs试验敏感度为93.83%(76/81),其中肺结核和肺外结核的敏感度分别为95.74%、91.17%,敏感度比较差异无统计学意义(P0.05)。特异度为84.56%(115/136)。其中肺结核和肺外结核的特异度分别为80.00%、91.07%,肺外结核的特异度明显高于肺结核,差异具有统计学意义(P0.05)。5个单位皮肤试验敏感度和特异度分别为56.79%、62.50%。IGRAs试验敏感度、特异度、阳性预测值、阴性预测值均高于TST皮肤试验,差异具有统计学意义(P0.05)。结论 IGRAs试验在肺结核与肺外结核中有较高敏感度和特异度,特别是在排除结核的诊断上具有较高的临床价值。     

T-SPOT. TB和结核菌素试验在骨关节结核诊断中的敏感性和特异性分析

目的分析结核感染T细胞免疫斑点试验(T-SPOT. TB)和结核菌素试验在骨关节结核诊断中的应用价值。方法收集2014年1月至2016年8月医院采用手术或保守治疗的骨关节结核患者94例,以及2016年2月至2017年1月骨外科收治的手术治疗的骨关节病患者50例作为研究对象,均进行结核菌素试验与T-SPOT. TB,对比2种方法的诊断效用。结果结核菌素试验诊断敏感性、特异性、阳性预测值、阴性预测值、符合率分别为46.81%、98.00%、97.78%、49.49%、64.58%,TSPOT. TB则为93.62%、100.00%、100.00%、89.29%、95.83%,结核菌素试验敏感性、阴性预测值、符合率低于T-SPOT. TB及2种方法联合检测,差异有统计学意义(P0.05)。T-SPOT.TB出现6例漏诊,均为早期脊柱结核病,表现为空洞形成,未见脊柱神经缺损。结核菌素试验出现1例误诊,50例漏诊,漏诊者主要病情相对较轻,伴风湿关节病等免疫疾病的患者。结论 TSPOT. TB是诊断骨关节结核病的理想方法,但存在干扰因素,需合理应用,结核菌素试验操作简单,尽管敏感性不足,但在结核病筛查中有一定的价值。     

结核感染T细胞斑点试验在结核性疾病中的诊断价值

目的评价γ-干扰素释放分析结核感染T细胞斑点试验（T-SPOT,TB）检测在结核性疾病中的诊断价值。方法对仁济医院疑诊或待排结核患者进行T—SPOT．TB检测。结果T—SPOT．TB检测在结核性疾病阳性检出率为94．4％（17／18）,明显高于PPD的47．1％（8／17）、结核抗体检查的12．5％（2／16）、结核PCR的16．7％（2／12）、抗酸杆菌涂片的7．7％（1／13）、结核菌培养的27．3％（3／11）,差异有统计学意义（P〈0．05）。T-SPOT．TB检测诊断结核性疾病敏感性、特异性分别为94．4％、95．2％,显著优于PPD。结论T—SPOT．TB检测是诊断结核的快速敏感方法,在结核性疾病诊断中有重要价值。     

QuantiFERON-TB Gold in the diagnosis of active tuberculosis

QuantiFERON-TB Gold (QFT) is an indirect diagnostic test for latent tuberculosis (TB) infection and active TB. This study aimed to evaluate and compare QFT and the tuberculin skin test (TST) for the diagnosis of active TB disease, not bacteriologically verified at the time of therapy initiation. Seventy-three patients with suspected active TB were examined. Further diagnostic steps confirmed the diagnosis of active TB in 53 persons. QFT was positive in 43 persons (81%), negative in seven (13%), and indeterminate results were found in three (6%). The sensitivity of the test was 86% in those with valid results, significantly higher than that for the TST (62%), and the correlation between the two tests was not high (55%). The QFT test is a useful addition to existing methods for the diagnosis of active TB.     

QuantiFERON-TB Gold assay for the diagnosis of latent tuberculosis infection

Tuberculin skin test (TST) has been used for 100 years for the diagnosis of latent tuberculosis (TB) infection (LTBI). In recent years, increasing interest in the diagnosis of TB has led to the development of new assays. QuantiFERON-TB Gold (QFT-G) is an IFN-gamma-release assay that measures the release of interferon after stimulation in vitro by Mycobacterium tuberculosis antigens. The main advantage of this assay with respect to TST is the lack of crossreaction with bacillus Calmette-Guérin and most nontuberculous mycobacteria. QFT-G also eliminates the need for the patient to return for test reading in 48-72 h. In the immunocompromised host and in pediatric populations, studies suggest that the QFT-G better correlates with the risk of TB than the TST, but data remain inconclusive. In contrast to TST, there are no prospective studies regarding the association of the QFT-G result and the risk for development of TB. Given its advantages, the QFT-G may become the standard test for the diagnosis of LTBI.     

Rapid detection of Mycobacterium tuberculosis in sputum by Patho-TB kit in comparison with direct microscopy and culture

The usefulness of a new rapid diagnostic test (Patho-TB) using antibodies specific to mycobacterial antigens was evaluated for the rapid discrimination between pulmonary tuberculosis (TB) and non-TB pulmonary diseases on sputa. One hundred sputa collected from 79 active TB patients and from 21 patients with non-TB pulmonary diseases (asthma and chronic obstructive pulmonary disease) were enrolled into the study and tested for the presence of Mycobacterium tuberculosis by Ziehl–Neelsen smear, Patho-TB kit, and Löwenstein–Jensen culture. The sensitivity, specificity, positive predictive value, and negative predictive value of the Patho-TB test were 95%, 100%, 100%, and 84%, respectively. Patho-TB test is simple, quick, and easy to perform. Its sensitivity, specificity, and positive predictive value are satisfactory. Therefore, it could be used as a screening test in poorly equipped laboratories of TB endemic areas.