Oxford University Clinical Research Unit, Hospital for Tropical Diseases, 764 Vo Van Kiet, District 5, Ho Chi Minh City, Vietnam.
BMC Infect Dis. 2013 Jan 23;13:31. doi: 10.1186/1471-2334-13-31.
Tuberculosis (TB) in children is rarely confirmed due to the lack of effective diagnostic tools; only 10 to 15% of pediatric TB is smear positive due to paucibacillary samples and the difficulty of obtaining high-quality specimens from children. We evaluate here the accuracy of Xpert MTB/RIF in comparison with the Micoroscopic observation drug susceptibility (MODS) assay for diagnosis of TB in children using samples stored during a previously reported evaluation of the MODS assay.
Ninety-six eligible children presenting with suspected TB were recruited consecutively at Pham Ngoc Thach Hospital in Ho Chi Minh City Viet Nam between May to December 2008 and tested by Ziehl-Neelsen smear, MODS and Mycobacterial growth Indicator (MGIT, Becton Dickinson) culture. All samples sent by the treating clinician for testing were included in the analysis. An aliquot of processed sample deposit was stored at -20°C and tested in the present study by Xpert MTB/RIF test. 183 samples from 73 children were available for analysis by Xpert. Accuracy measures of MODS and Xpert were summarized.
The sensitivity (%) in detecting children with a clinical diagnosis of TB for smear, MODS and Xpert were 37.9 [95% CI 25.5; 51.6], 51.7 [38.2; 65.0] and 50.0 [36.6; 63.4], respectively (per patient analysis). Xpert was significantly more sensitive than smear (P=0.046). Testing of additional samples did not increase case detection for MODS while testing of a second sputum sample by Xpert detected only two additional cases. The positive and negative predictive values (%) of Xpert were 100.0 [88.0; 100.0] and 34.1 [20.5; 49.9], respectively, while those of MODS were 96.8 [83.3; 99.9] and 33.3 [19.6; 49.5].
MODS culture and Xpert MTB/RIF test have similar sensitivities for the detection of pediatric TB. Xpert MTB RIF is able to detect tuberculosis and rifampicin resistance within two hours. MODS allows isolation of cultures for further drug susceptibility testing but requires approximately one week to become positive. Testing of multiple samples by xpert detected only two additional cases and the benefits must be considered against costs in each setting. Further research is required to evaluate the optimal integration of Xpert into pediatric testing algorithms.
由于缺乏有效的诊断工具，儿童结核病很少得到确诊；由于样本中结核菌数量少，以及难以从儿童中获得高质量的标本，只有 10%至 15%的儿童结核病痰涂片阳性。我们在此评估 Xpert MTB/RIF 与微量分光光度法（MODS）检测在使用先前报道的 MODS 检测评估中储存的样本时对儿童结核病的诊断准确性。
2008 年 5 月至 12 月，连续招募了 96 名在越南胡志明市范内科塔医院就诊的疑似结核病患儿，采用萋-尼氏染色、MODS 和分枝杆菌生长指示剂（MGIT，BD）培养进行检测。所有经治疗医生送检的样本均纳入分析。处理后的样本部分储存于-20°C，并在本研究中采用 Xpert MTB/RIF 检测。对 73 名儿童的 183 份样本进行 Xpert 分析。总结了 MODS 和 Xpert 的准确性指标。
对有临床诊断为结核病的患儿进行痰涂片、MODS 和 Xpert 检测，其敏感性（%）分别为 37.9[95%CI 25.5;51.6]、51.7[38.2;65.0]和 50.0[36.6;63.4]（以患者为单位进行分析）。Xpert 比涂片法更敏感（P=0.046）。对 MODS 进行额外样本检测并未增加病例检出率，而对 Xpert 进行第二次痰样本检测仅检出两例额外病例。Xpert 的阳性和阴性预测值（%）分别为 100.0[88.0;100.0]和 34.1[20.5;49.9]，MODS 的阳性和阴性预测值分别为 96.8[83.3;99.9]和 33.3[19.6;49.5]。
MODS 培养和 Xpert MTB/RIF 检测对儿童结核病的检测具有相似的敏感性。Xpert MTB RIF 能够在两小时内检测到结核分枝杆菌和利福平耐药性。MODS 可以分离培养物进行进一步的药敏试验，但需要大约一周才能呈阳性。对 Xpert 进行多次样本检测仅检出两例额外病例，必须根据成本在每个环境中考虑获益。需要进一步研究以评估 Xpert 纳入儿童检测算法的最佳方法。
