Poudel A, Pandey B D, Lekhak B, Rijal B, Sapkota B R, Suzuki Y
Department of Microbiology, Kathmandu Medical College, Sinamangal, Nepal.
Kathmandu Univ Med J (KUMJ). 2009 Apr-Jun;7(26):109-14. doi: 10.3126/kumj.v7i2.2701.
Tuberculosis is a global health problem and the situation is worsening with newer incidences of drug resistance and HIV association. Diagnosis of tuberculosis can be done by many methods and test, culture of sputum being the ideal one. Nucleic acid amplification (NAA) assay are more time efficient one, that amplify and detect specific nucleic acid sequences allows rapid, sensitive and specific detection of M. tuberculosis in sputum samples.
The present study intends to compile the clinical presentations of the pulmonary tuberculosis (PTB) patients and to evaluate the efficacy of in-house loop-mediated isothermal amplification (LAMP) in detecting Mycobacterium tuberculosis in sputum samples by comparing with microscopy and culture.
Two hundred two sputum samples were collected from 202 patients at National Tuberculosis Center, Bhaktapur, Nepal. Complete clinical profiling, epidemiological data and record on BCG vaccination were noted and the samples were subjected for microscopy, culture and in-house LAMP with six primers specific for 16S RNA gene of Mycobacterium tuberculosis.
Of the 176 cases of clinical profiling, productive cough was most common symptom in 147 (83.52%), followed by chest pain 136 (77.27%), fever 133 (75.56%) and haemoptysis 61 (34.66%). There was a statistically significant association between BCG vaccination and development of TB (chi(2)=5.33, P=0.02). Of 202 cases, 115 (56.93%) were chest X-ray positive, 101(50%) were direct smear-positive and 100 (49.51%) were culture positive. LAMP had a sensitivity of 97% and specificity of 94.12% while comparing with culture. In addition, its sensitivity and specificity were 91.09% and 89.11% respectively with reference to microscopy.
As in our previous study, overall, the result of present study further confirms that the in-house LAMP is a simple, rapid, sensitive and specific DNA amplification technique for PTB diagnosis. Because of rapidity of microscopy and specificity of culture, in-house LAMP assay can be used as a very powerful and useful supplementary tool with complete clinical profiling of the patients for rapid diagnosis of TB in both AFB-positive and negative cases who are suspected as PTB in disease endemic country like Nepal.
结核病是一个全球性的健康问题，随着耐药性和与艾滋病病毒关联的新发病例出现，情况正在恶化。结核病的诊断可通过多种方法和检测手段进行，痰培养是理想的方法。核酸扩增（NAA）检测效率更高，它能扩增和检测特定核酸序列，可对痰标本中的结核分枝杆菌进行快速、灵敏且特异的检测。
本研究旨在汇总肺结核（PTB）患者的临床表现，并通过与显微镜检查和培养法比较，评估自制的环介导等温扩增（LAMP）技术检测痰标本中结核分枝杆菌的效果。
从尼泊尔巴克塔普尔国家结核病中心的202例患者处收集了202份痰标本。记录完整的临床概况、流行病学数据以及卡介苗接种情况，并将标本进行显微镜检查、培养以及用针对结核分枝杆菌16S RNA基因的六种引物进行自制LAMP检测。
在176例临床概况中，咳痰是最常见症状，有147例（83.52%），其次是胸痛136例（77.27%）、发热133例（75.56%）和咯血61例（34.66%）。卡介苗接种与结核病发病之间存在统计学显著关联（χ² = 5.33，P = 0.02）。202例中，115例（56.93%）胸部X线检查呈阳性，101例（50%）直接涂片呈阳性，100例（49.51%）培养呈阳性。与培养法相比，LAMP的灵敏度为97%，特异性为94.12%。此外，相对于显微镜检查，其灵敏度和特异性分别为91.09%和89.11%。
正如我们之前的研究一样，总体而言，本研究结果进一步证实自制LAMP是一种用于PTB诊断的简单、快速、灵敏且特异的DNA扩增技术。鉴于显微镜检查的快速性和培养法的特异性，在像尼泊尔这样的疾病流行国家，自制LAMP检测可作为一种非常强大且有用的辅助工具，结合患者完整的临床概况，对疑似PTB的抗酸杆菌阳性和阴性病例进行结核病的快速诊断。
