Barani Ramya, Sarangan Gopalsamy, Antony Tessa, Periyasamy Soundararajan, Kindo Anupma Jyoti, Srikanth Padma
Department of Microbiology , Sri Ramachandra University, Porur, Chennai, India.
J Infect Dev Ctries. 2012 Jan 12;6(1):46-52. doi: 10.3855/jidc.1302.
Tuberculosis (TB) causes significant morbidity and mortality worldwide as one of the leading infectious diseases. In India, more than 1.8 million new cases occur every year. Rapid and accurate diagnosis of TB would improve patient care and limit its transmission. This study aimed to evaluate a dual target polymerase chain reaction (PCR) diagnostic assay to detect Mycobacterium tuberculosis from pulmonary and extra-pulmonary samples at a tertiary care centre in South India.
Samples were collected from patients with a low index of suspicion of TB. Acid-fast smears were performed by Auramine O fluorescent microscopy and PCR was performed by using two site-specific primer pairs targeting IS6110 by nested PCR and TRC4 by conventional PCR. Amplified products for IS6110 and/or TRC4 were indicative of M. tuberculosis.
Among 114 (19 pulmonary and 95 extra-pulmonary) samples tested by PCR assay, 12 (11%) were positive for both IS6110 and TRC4, of which 11 (10%) were non-respiratory and one was (1%) respiratory in origin. PCR for TRC4 alone was positive for eight (7%) non-respiratory and two (2%) respiratory samples, while IS6110 alone tested positive for six (5%) non-respiratory samples and one (1%) respiratory sample. Of a total of 29 PCR positive samples, 17 (15 %) were acid-fast smear positive.
Although the target site of IS6110 is specific for M. tuberculosis, some strains from South India may lack this region. Therefore, the use of an additional target site (TRC4) is required for improved detection of M. tuberculosis.
结核病作为主要的传染病之一，在全球范围内导致了显著的发病率和死亡率。在印度，每年有超过180万新发病例。结核病的快速准确诊断将改善患者护理并限制其传播。本研究旨在评估一种双靶点聚合酶链反应（PCR）诊断检测方法，以在印度南部的一家三级护理中心从肺部和肺外样本中检测结核分枝杆菌。
从结核病疑似指数较低的患者中采集样本。通过金胺O荧光显微镜进行抗酸涂片检查，并使用两对位点特异性引物，通过巢式PCR靶向IS6110以及通过常规PCR靶向TRC4进行PCR检测。IS6110和/或TRC4的扩增产物表明存在结核分枝杆菌。
在通过PCR检测的114份样本（19份肺部样本和95份肺外样本）中，12份（11%）IS6110和TRC4均呈阳性，其中11份（10%）为非呼吸道来源，1份（1%）为呼吸道来源。仅TRC4的PCR检测中，8份（7%）非呼吸道样本和2份（2%）呼吸道样本呈阳性，而仅IS6110检测中，6份（5%）非呼吸道样本和l份（1%）呼吸道样本呈阳性。在总共29份PCR阳性样本中，17份（15%）抗酸涂片呈阳性。
尽管IS6110的靶位点对结核分枝杆菌具有特异性，但印度南部的一些菌株可能缺乏该区域。因此，需要使用额外的靶位点（TRC4）来提高结核分枝杆菌的检测率。
