Connell T G, Curtis N, Ranganathan S C, Buttery J P
Infectious Diseases Unit, Department of General Medicine and Murdoch Children's Institute, Royal Children's Hospital Melbourne, Flemington Road, Parkville 3052, Victoria, Australia.
Thorax. 2006 Jul;61(7):616-20. doi: 10.1136/thx.2005.048033. Epub 2006 Apr 6.
The diagnosis of latent Mycobacterium tuberculosis (MTB) infection with a tuberculin skin test (TST) in children is complicated by the potential influence of prior exposure to Bacille Calmette Geurin (BCG) vaccination or environmental mycobacteria. A whole blood assay has recently been developed to quantitatively measure interferon gamma (IFN-gamma) production by lymphocytes specific to the MTB antigens ESAT-6 and CFP-10, but its use and assessment in children has been limited. A study was undertaken to compare the performance of the whole blood IFN-gamma assay with the TST in diagnosing latent tuberculosis (TB) infection or TB disease in children in routine clinical practice.
One hundred and six children with a high risk of latent TB infection or TB disease were enrolled in the study. High risk was defined as contact with TB disease, clinical suspicion of TB disease, or recent arrival from an area of high TB prevalence. The whole blood IFN-gamma assay was undertaken in 101 children.
Seventeen (17%) of the 101 assays yielded inconclusive results due to failure of positive or negative control assays. There was poor correlation between the whole blood IFN-gamma assay and the TST (kappa statistic 0.3) with 26 (70%) of the 37 children defined as latent TB infection by TST having a negative whole blood IFN-gamma assay. There were no instances of a positive whole blood IFN-gamma assay with a negative TST. Mitogen (positive) control IFN-gamma responses were significantly correlated with age (Spearman's coefficient = 0.53, p<0.001) and, in children with latent TB infection identified by TST, those with a positive IFN-gamma assay were older (median 12.9 v 6.92 years, respectively, p = 0.007). The whole blood IFN-gamma assay was positive in all nine children with TB disease.
There was poor agreement between the whole blood IFN-gamma assay and TST for the diagnosis of latent TB. The whole blood IFN-gamma assay may have lower sensitivity than the TST in diagnosing TB infection in children. A significant proportion of whole blood IFN-gamma assays fail when used as a screening assay in routine practice.
在儿童中，结核菌素皮肤试验（TST）用于诊断潜伏性结核分枝杆菌（MTB）感染时，会受到既往接种卡介苗（BCG）或接触环境分枝杆菌的潜在影响，使诊断变得复杂。最近开发了一种全血检测方法，用于定量测量淋巴细胞对MTB抗原ESAT-6和CFP-10产生的干扰素γ（IFN-γ），但其在儿童中的应用和评估有限。本研究旨在比较全血IFN-γ检测与TST在常规临床实践中诊断儿童潜伏性结核（TB）感染或TB疾病的性能。
106名有潜伏性TB感染或TB疾病高风险的儿童纳入研究。高风险定义为接触TB疾病、临床怀疑TB疾病或近期来自TB高流行地区。101名儿童进行了全血IFN-γ检测。
101次检测中有17次（17%）因阳性或阴性对照检测失败而结果不确定。全血IFN-γ检测与TST之间的相关性较差（kappa统计量为0.3），37名被TST定义为潜伏性TB感染的儿童中，有26名（70%）全血IFN-γ检测为阴性。没有出现全血IFN-γ检测阳性而TST阴性的情况。丝裂原（阳性）对照IFN-γ反应与年龄显著相关（Spearman系数=0.53，p<0.001），在TST确定为潜伏性TB感染的儿童中，IFN-γ检测阳性的儿童年龄较大（中位数分别为12.9岁和6.92岁，p = 0.007）。9名TB疾病儿童的全血IFN-γ检测均为阳性。
全血IFN-γ检测与TST在诊断潜伏性TB方面的一致性较差。在诊断儿童TB感染时，全血IFN-γ检测的敏感性可能低于TST。在常规实践中用作筛查检测时，相当一部分全血IFN-γ检测会失败。
