Views: 96 Author: Site Editor Publish Time: 2021-02-18 Origin: Site
The sampling swab is generally composed of three parts, namely the sampling rod, the swab head and the glue for connection. However, due to different types of raw materials, manufacturing processes, and technical levels, the current products on the market are also uneven. Although it does not affect the sampling process, it directly affects the quality of nucleic acid extraction and nucleic acid testing, and even the negative and positive results of the test. This article gives some suggestions on the selection of sampling swabs for the new coronavirus.
1、How to choose the sampling swab material?
New Coronary Pneumonia Laboratory Testing Technical Guidelines (Third Edition)  has clearly regulated the material of the sampling swab, showing that, both nasal swabs and throat swabs should be swabs with
polypropylene fiber tips.
In addition, the US CDC issued 《 Interim Guidelines for Collecting, Handling, and Testing Clinical Specimens from Patients Under Investigation(PUIs) for 2019 Novel Coronavirus (2019-nCoV)》 February 2, 2020, which showed the requirements for the collection swabs used in the collection of nasal and pharyngeal samples (see the red box)。
Therefore, the material of the sampling rod should be a medical grade plastic sampling rod.
2、How to choose the material of the swab head？
Compared with the traditional twisted swab (although it is also made of synthetic fiber), the "synthetic fiber flocking swab" is to glue a large number of tiny nylon fibers to the top of a plastic rod, thus making a swab far beyond the traditional. In term of the high-performance fluffy swab, the amount of
collected samples and released samples is 3 times higher than traditional twisted swab. It does not damage the virus samples, which can ensure the survival rate of the virus samples, and has no fatty acid residues, and does not inactivate certain viruses and inhibit PCR detection substance.
Different swab heads
(the left is the traditional sampling swab head; the right is the flocking swab head)
Dakmaso et al.,  believed that the villi on the nylon flocked swab can increase the surface area of the swab and the physical evidence, which can maximize the transfer of cells to the surface of the swab, and fullyrelease the adhered cells during DNA extraction, thereby obtaining ahigher concentration Template DNA.
Daley et al.,  showed that nylon flocking swabs are 20-60% more efficient than other swabs in transferring microorganisms on the surface of objects.
A previous study by the Public Security Bureau’s Physical Evidence
Appraisal Institute  also confirmed that nylon flocking swabs are better than cotton swabs for blood stain testing, and the advantage is more obvious in micro blood stain testing.
The research of Infectious Disease Center of West China Hospital of Sichuan University  confirmed that the positive nucleic acid detection rate of cotton swab virus was 54%, and the positive nucleic acid detection rate of nylon swab virus was 89%, the difference was statistically significant
(Chi-square test =3.8504, P =0.0497).
Bioteke used a kind of glue, associated with various sampling swab heads made of medical grade synthetic fibers of common brands on the market, and the same sample is used for nucleic acid extraction. The nucleic acid extraction results are as follows:
The results showed that different flocking has a greater impact on nucleic acid extraction, and the initial copy amount of the sample directly affects the results of nucleic acid detection.
The above conclusions revealed that, compared with wood stick cotton swabs, nylon flocked swabs can guarantee the survival rate of virus samples, have no fatty acid residues, and contain no substances that inactivate certain viruses and inhibit PCR detection. Therefore, the swab head material should be nylon flocking swab head. As the product does not have national quality standards, when purchasing, the manufacturer is required to provide corresponding research and development materials or testing reports to ensure the extraction effect. And because the swab head is in direct contact with the human body, the manufacturer is required to provide a biological evaluation test report to confirm the safety of the product.
3、How does glue affect test results？
Bioteke also purchased medical glue from some common brands on the market, compared sampling swabs made with different glue, and used the same sample to perform nucleic acid extraction. The nucleic acid extraction results are as follows:
It can be seen that different glues have a greater impact on nucleic acid extraction, and the initial copy amount of the sample directly affects the results of nucleic acid detection.
On the basis of preliminary research and our experiments, Bioteke selects raw materials, and the manufacturing process has undergone multiple
verifications, and introduced three flocking swabs:
4、 Features of Bioteke Sampling Swab
a) The flocking process does not damage the virus sample;
b) It can be used with Bioteke UTM, VTM or ITM preservation solutions to meet multiple needs;
c) Selected raw materials, matched with Bioteke nucleic acid extraction kit to ensure the initial copy quantity of the sample.
5、 The inspection reports that Bioteke has obtained for sampling swab products
EN11137-2：2013 ISO EN11137-3：2017
Wujiang Dasheng Testing Technology Co., Ltd.