在BACTEC MGIT 960和BACTEC 9120血培养中使用Capilia TB检测法快速鉴定结核分枝杆菌复合群的评估。
Evaluation of Capilia TB assay for rapid identification of Mycobacterium tuberculosis complex in BACTEC MGIT 960 and BACTEC 9120 blood cultures.
作者信息
Muchwa Christopher, Akol Joseph, Etwom Alfred, Morgan Karen, Orikiriza Patrick, Mumbowa Francis, Odong Paul R, Kateete David P, Eisenach Kathleen D, Joloba Moses L
机构信息
Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences, Kampala, Uganda.
出版信息
BMC Res Notes. 2012 Jan 19;5:44. doi: 10.1186/1756-0500-5-44.
BACKGROUND
Capilia TB is a simple immunochromatographic assay based on the detection of MPB64 antigen specifically secreted by the Mycobacterium tuberculosis complex (MTC). Capilia TB was evaluated for rapid identification of MTC from BACTEC MGIT 960 and BACTEC 9120 systems in Kampala, Uganda. Since most studies have mainly dealt with respiratory samples, the performance of Capilia TB on blood culture samples was also evaluated.
METHODS
One thousand samples from pulmonary and disseminated tuberculosis (TB) suspects admitted to the JCRC clinic and the TB wards at Old Mulago hospital in Kampala, Uganda, were cultured in automated BACTEC MGIT 960 and BACTEC 9120 blood culture systems. BACTEC-positive samples were screened for purity by sub-culturing on blood agar plates. Two hundred and fifty three (253) samples with Acid fast bacilli (AFB, 174 BACTEC MGIT 960 and 79 BACTEC 9120 blood cultures) were analyzed for presence of MTC using Capilia TB and in-house PCR assays.
RESULTS
The overall Sensitivity, Specificity, Positive and Negative Predictive values, and Kappa statistic for Capilia TB assay for identification of MTC were 98.4%, 97.6%, 97.7%, 98.4% and 0.96, respectively. Initially, the performance of in-house PCR on BACTEC 9120 blood cultures was poor (Sensitivity, Specificity, PPV, NPV and Kappa statistic of 100%, 29.3%,7%, 100% and 0.04, respectively) but improved upon sub-culturing on solid medium (Middlebrook 7H10) to 100%, 95.6%, 98.2%, 100% and 0.98, respectively. In contrast, the Sensitivity and Specificity of Capilia TB assay was 98.4% and 97.9%, respectively, both with BACTEC blood cultures and Middlebrook 7H10 cultured samples, revealing that Capilia was better than in-house PCR for identification of MTC in blood cultures. Additionally, Capilia TB was cheaper than in-house PCR for individual samples ($2.03 vs. $12.59, respectively), and was easier to perform with a shorter turnaround time (20 min vs. 480 min, respectively).
CONCLUSION
Capilia TB assay is faster and cheaper than in-house PCR for rapid identification of MTC from BACTEC MGIT 960 and BACTEC 9120 culture systems in real-time testing of AFB positive cultures.
背景
Capilia TB是一种基于检测结核分枝杆菌复合群（MTC）特异性分泌的MPB64抗原的简易免疫层析检测方法。在乌干达坎帕拉，对Capilia TB从BACTEC MGIT 960和BACTEC 9120系统中快速鉴定MTC进行了评估。由于大多数研究主要涉及呼吸道样本，因此还评估了Capilia TB在血培养样本上的性能。
方法
从乌干达坎帕拉JCRC诊所和老穆拉戈医院结核病病房收治的疑似肺结核和播散性结核病患者中采集1000份样本，在自动化BACTEC MGIT 960和BACTEC 9120血培养系统中培养。通过在血琼脂平板上进行传代培养，对BACTEC阳性样本进行纯度筛选。使用Capilia TB和内部PCR检测方法，对253份抗酸杆菌（AFB，174份来自BACTEC MGIT 960血培养，79份来自BACTEC 9120血培养）样本进行MTC检测。
结果
Capilia TB检测方法鉴定MTC的总体敏感性、特异性、阳性和阴性预测值以及Kappa统计量分别为98.4%、97.6%、97.7%、98.4%和0.96。最初，内部PCR在BACTEC 9120血培养样本上的性能较差（敏感性、特异性、阳性预测值、阴性预测值和Kappa统计量分别为100%、29.3%、7%、100%和0.04），但在固体培养基（Middlebrook 7H10）上传代培养后有所改善，分别为100%、95.6%、98.2%、100%和0.98。相比之下，Capilia TB检测方法在BACTEC血培养样本和Middlebrook 7H10培养样本上的敏感性和特异性分别为98.4%和97.9%，这表明在血培养样本中鉴定MTC时，Capilia TB优于内部PCR。此外，Capilia TB检测单个样本的成本比内部PCR低（分别为2.03美元和12.59美元），操作更简便，周转时间更短（分别为20分钟和480分钟）。
结论
在对AFB阳性培养物进行实时检测时，从BACTEC MGIT 960和BACTEC 9120培养系统中快速鉴定MTC，Capilia TB检测方法比内部PCR更快、更便宜。
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