Nour-Neamatollahi Ali, Siadat Seyed Davar, Yari Shamsi, Tasbiti Alireza Hadizadeh, Ebrahimzadeh Nayereh, Vaziri Farzam, Fateh Abolfazl, Ghazanfari Morteza, Abdolrahimi Farid, Pourazar Shahin, Bahrmand Ahmadreza
Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran.
Saudi J Biol Sci. 2018 Mar;25(3):418-425. doi: 10.1016/j.sjbs.2016.01.026. Epub 2016 Mar 9.
, acid fast bacilli from the family of , is the causative agent of most cases of tuberculosis. Tuberculosis, as a communicable disease, remains a serious public health threat, killing more than one million people globally every year. Primary diagnosis of tuberculosis bacilli (TB) relies mainly on microscopic detection of acid fast bacilli (AFB), but the method suffers from low sensitivity and the results largely depend on the technician's skill. New diagnostic tools are necessary to be introduced for rapid and accurate detection of the bacilli in sputum samples. We, in collaboration with Anda Biologicals, have developed a new platform, named as "Patho-tb", for rapid detection of AFB with high sensitivity and with low dependence on human skills. Evaluation of Patho-tb test performance was done in two settings: (1) primary field study conducted using 38 sputa from high TB prevalence area of Iran (Zabol city near to the Afghanistan border), and (2) main study conducted using 476 sputa from Tehran, capital of Iran. Patho-tb was applied for processed sputum samples in parallel with routine diagnostic methods (including AFB microscopy, culture and PCR). All test results were compared to final clinical diagnostic state of an individual and diagnostic sensitivity (DSe), specificity, positive predictive value, negative predictive value and accuracy of each test results were calculated using standard formulations. Analytical sensitivity and specificity of the Patho-tb test were also determined. Calculated values for five above mentioned parameters are as follows: for field study: AFB (DSe: 29.6, DSp: 81.8, PPV: 80, NPV: 23.1, AC: 44.7), Patho-tb (DSe: 63, DSp: 72.7, PPV: 85, NPV: 44.4, AC: 65.8), and for main study: AFB (DSe: 86.1, DSp: 99.4, PPV: 98.5, NPV: 93.9, AC: 95.2), Patho-tb (DSe: 97.4, DSp: 92.9, PPV: 86.5, NPV: 98.7, AC: 94.3). Reproducibility of Patho-tb test results were near to 100% (Cohen's kappa value between 0.85 and 1). The detection limit of Patho-tb test with 100% positivity rate was 3 × 10 cells/ml of sputum. In the field study, Patho-tb test was 33.4% more sensitive than AFB microscopy, while the improvement was only 11.3% during the main study. Patho-tb results are easy to interpret and the test can be merged with other screening tests, like AFB. Totally, Patho-tb test alone or in conjunction with AFB microscopy is a useful screening tool for TB detection especially in poor geographical lab conditions.
分枝杆菌属的抗酸杆菌是大多数结核病病例的病原体。结核病作为一种传染病，仍然是严重的公共卫生威胁，每年在全球导致超过100万人死亡。结核杆菌（TB）的初步诊断主要依靠抗酸杆菌（AFB）的显微镜检测，但该方法灵敏度较低，结果很大程度上取决于技术人员的技能。需要引入新的诊断工具来快速、准确地检测痰样本中的杆菌。我们与安达生物公司合作，开发了一个名为“Patho-tb”的新平台，用于高灵敏度且低依赖人工技能地快速检测AFB。在两种情况下对Patho-tb测试性能进行了评估：（1）在伊朗结核病高流行地区（靠近阿富汗边境的扎博勒市）使用38份痰液进行的初步现场研究，以及（2）在伊朗首都德黑兰使用476份痰液进行的主要研究。将Patho-tb应用于处理后的痰样本，并与常规诊断方法（包括AFB显微镜检查、培养和PCR）并行使用。将所有测试结果与个体的最终临床诊断状态进行比较，并使用标准公式计算每个测试结果的诊断灵敏度（DSe）、特异性、阳性预测值、阴性预测值和准确性。还确定了Patho-tb测试的分析灵敏度和特异性。上述五个参数的计算值如下：对于现场研究：AFB（DSe：29.6，DSp：81.8，PPV：80，NPV：23.1，AC：44.7），Patho-tb（DSe：63，DSp：72.7，PPV：85，NPV：44.4，AC：65.8），对于主要研究：AFB（DSe：86.1，DSp：99.4，PPV：98.5，NPV：93.9，AC：95.2），Patho-tb（DSe：97.4，DSp：92.9，PPV：86.5，NPV：98.7，AC：94.3）。Patho-tb测试结果的重现性接近100%（科恩kappa值在0.85至1之间）。Patho-tb测试100%阳性率的检测限为每毫升痰液3×10个细胞。在现场研究中，Patho-tb测试比AFB显微镜检查灵敏度高33.4%，而在主要研究期间改善仅为11.3%。Patho-tb结果易于解释，该测试可与其他筛查测试（如AFB）合并。总体而言，单独的Patho-tb测试或与AFB显微镜检查结合使用是结核病检测的有用筛查工具，特别是在地理条件较差的实验室环境中。
