Abstract

Most point-of-care tests (POCT) use swabs for sampling and/or for applying a sample on the test. A variety of swabs differing in tip materials is commercially available. Different tip materials have different chemical and physical characteristics which might influence the specimen collection and release. We investigated properties of various types of swabs used in clinical diagnostics with focusing on two kinds of analytes, DNA and proteins, which are most often used targets in POCT. As the model samples we used diphtheria toxoid NIBSC 69/017 for investigating recovery of protein analytes such as antigens and bacterial strains of Escherichia coli ATCC 25922, diphtheria toxin-producing Corynebacterium diphtheriae NCTC 10648, and the clinical isolate nontoxigenic C. diphtheriae 5820/15 for investigating the recovery of nucleic acids. We investigated four types of swabs most commonly used in clinical diagnostics in terms of absorption capacity and efficiency of release of nucleic acids and proteins. Volume uptake was measured in milligrams. For DNA release various washing out buffers were used and the amount of released DNA was measured spectrophotometrically. The amount of protein released from the swabs were examined using the Lowry assay. We observed statistically significant differences (p < 0.05) in the mean weights of absorbed liquid, in the DNA recovery and protein recovery by the four variety of swab examined. However, the efficiency of DNA and protein release was not correlated to the absorbed volume of a sample, but rather to the properties of swabs. The swab composition and structure can have a significant impact on the collection and release efficiency of a sample. Therefore, validation of POCT in relation to the used swabs for sampling is really important. The use of inappropriate swabs could lead to false negative or misleading analysis results.

中文翻译：

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拭子类型对即时检验结果的影响

摘要

大多数即时检验（POCT）使用拭子进行采样和/或在测试中施加样品。市场上可买到各种尖端材料不同的药签。不同的吸头材料具有不同的化学和物理特性，可能会影响样品的收集和释放。我们研究了临床诊断中使用的各种类型拭子的特性，重点研究了两种分析物，即DNA和蛋白质，这是POCT中最常用的靶标。作为模型样本，我们使用了白喉类毒素NIBSC 69/017来研究蛋白质分析物的回收，例如大肠杆菌ATCC 25922的抗原和细菌菌株，产生白喉毒素的白喉棒状杆菌NCTC 10648，以及临床分离的无毒物质白喉衣原体5820/15，用于研究核酸的回收。我们就吸收能力和核酸和蛋白质释放效率研究了四种最常用于临床诊断的拭子。体积吸收以毫克为单位。为了释放DNA，使用了各种洗涤缓冲液，并用分光光度法测量了释放的DNA量。使用Lowry分析法检查了从拭子释放的蛋白质量。我们观察到统计学上的显着差异（p ＜0.05）在吸收液体的平均重量中，在DNA回收率和蛋白质回收率方面通过四种棉签进行了检验。但是，DNA和蛋白质释放的效率与样品的吸收量无关，而与拭子的性质有关。拭子的组成和结构可能会对样品的收集和释放效率产生重大影响。因此，与用于采样的拭子相关的POCT验证非常重要。使用不合适的棉签可能会导致假阴性或误导性的分析结果。