Department of Bacteriology, ICMR-National Institute for Research in Tuberculosis, Chennai, Tamil Nadu, India.
Division of Epidemiology & Communicable Diseases, Indian Council of Medical Research, New Delhi, India.
Indian J Med Res. 2020 Oct;152(4):378-385. doi: 10.4103/ijmr.IJMR_2539_19.
BACKGROUND & OBJECTIVES: : Early case detection is essential to interrupt transmission and to prevent further spread of tuberculosis (TB) in high endemic settings. Nucleic acid amplification tests (NAATs) with visual read-outs are ideal as point-of-care tests. Truenat™ MTB is an indigenous chip-based NAAT for detection of Mycobacterium tuberculosis, which involves extraction of DNA and real-time polymerase chain reaction (PCR) using portable, automated, battery-operated instruments. The current multicentric study was aimed to evaluate Truenat for detection of MTB in sputum samples obtained from patients with presumptive pulmonary TB with reference to culture as gold standard and Xpert as a comparator.
: The study was conducted at four sites, namely ICMR-National Institute for Research in Tuberculosis, Chennai; All India Institute of Medical Sciences, New Delhi; ICMR-National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra; and National Institute of TB and Respiratory Diseases, New Delhi. Patients suspected to have TB were screened for eligibility. Two sputum samples were collected from each patient. Tests included smear, Xpert and Truenat directly from the sputum sample and culture by Lowenstein-Jensen (L-J) medium and MGIT960 from decontaminated pellets. Sample used for Truenat assay was coded. Resolution of Truenat false positives was done using an in-house PCR with TRC primers.
: The study enrolled 2419 presumptive TB patients after screening 2465 patients, and 3541 sputum samples were collected from the enrolled patients. Results of 2623 samples were available for analysis. Truenat showed a positivity rate of 48.5 per cent as compared to 37.0 per cent by Xpert. The sensitivities of Truenat and Xpert were was 88.3 and 79.7 per cent, respectively in comparison with culture.
INTERPRETATION & CONCLUSIONS: : Truenat MTB identified more positives among culture-confirmed samples than Xpert and had higher sensitivity. In addition, other advantageous operational features of Truenat MTB were identified which would be useful in field settings.
在高流行地区，早期病例检测对于阻断传播和防止结核病（TB）进一步扩散至关重要。具有目视读数的核酸扩增检测（NAAT）是理想的即时检测。Truenat™ MTB 是一种用于检测结核分枝杆菌的本土芯片 NAAT，涉及使用便携式、自动化、电池供电的仪器提取 DNA 和实时聚合酶链反应（PCR）。本多中心研究旨在评估 Truenat 在疑似肺结核患者的痰液样本中检测 MTB 的能力，以培养为金标准，以 Xpert 为比较。
该研究在四个地点进行，即 ICMR-国家结核病研究所，钦奈；全印度医学科学院，新德里；ICMR-国家 JALMA 麻风病和其他分枝杆菌病研究所，阿格拉；以及国家结核病和呼吸疾病研究所，新德里。对疑似结核病的患者进行筛查以确定其是否符合入选标准。从每位患者收集两份痰液样本。检测包括直接从痰液样本进行涂片、Xpert 和 Truenat 检测，以及使用 Lowenstein-Jensen（L-J）培养基和 MGIT960 从去污颗粒中进行培养。用于 Truenat 检测的样本进行编码。使用 TRC 引物的内部 PCR 解决 Truenat 假阳性问题。
在筛查 2465 名患者后，该研究共纳入了 2419 名疑似结核病患者，并从纳入的患者中收集了 3541 份痰液样本。可分析的结果为 2623 个样本。与 Xpert 相比，Truenat 的阳性率为 48.5%，而 Xpert 为 37.0%。与培养相比，Truenat 和 Xpert 的灵敏度分别为 88.3%和 79.7%。
与 Xpert 相比，Truenat MTB 在培养确认样本中检测到更多的阳性结果，且具有更高的灵敏度。此外，还确定了 Truenat MTB 的其他有利操作特性，这在现场环境中会很有用。
