Deka Sangeeta, Kalita Deepjyoti, Mangla Amit, Shankar Ravi
Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India.
Indian J Med Microbiol. 2020 Jul-Dec;38(3 & 4):451-456. doi: 10.4103/ijmm.IJMM_20_273.
In the current COVID-19 crisis, many national healthcare systems are confronted with a huge demand for mass testing and an acute shortage of diagnostic resources. Considering group testing as a viable solution, this pilot study was carried out to find the maximum number of samples that can be pooled together to accurately detect one positive sample carrying the severe acute respiratory syndrome-coronavirus 2 viral RNA from different pools. We made different pool sizes ranging from 5 to 30 samples. Three positive samples, covering the common range of polymerase chain reaction (PCR) threshold cycle values (an indirect indicator of viral load) observed in our patients, were selected, and different pools were made with known negative samples. The pools underwent real-time qualitative PCR for the determination of effective maximum pool size. It was observed that up to 20-sample pools of all positive samples could accurately be detected in terms of both E gene and RdRp gene, leading to considerable conservation of resources, time and workforce. However, while deciding the optimal pool size, the infection level in that particular geographical area and sensitivity of the test assay used (limit of detection) have to be taken into account.
在当前的新冠疫情危机中，许多国家的医疗系统面临着大规模检测的巨大需求以及诊断资源的严重短缺。考虑到混合检测是一种可行的解决方案，开展了这项试点研究，以找出能够合并在一起的最大样本数量，从而准确检测出不同混合样本中携带严重急性呼吸综合征冠状病毒2病毒RNA的一个阳性样本。我们制作了样本数量从5个到30个不等的不同混合样本。选择了三个阳性样本，涵盖了我们患者中观察到的聚合酶链反应（PCR）阈值循环值（病毒载量的间接指标）的常见范围，并与已知的阴性样本制成不同的混合样本。对这些混合样本进行实时定性PCR，以确定有效的最大混合样本数量。结果发现，就E基因和RdRp基因而言，所有阳性样本的20样本混合样本都能被准确检测出来，从而在资源、时间和人力方面实现了可观的节省。然而，在确定最佳混合样本数量时，必须考虑该特定地理区域的感染水平以及所使用检测方法的灵敏度（检测限）。
