What is a PCR test?

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What is a PCR test?

PCR (Polymerase Chain Reaction) is defined as a common name given to the reactions applied to enzymatically amplify a unique region between two segments of known sequence in DNA. PCR is known as a diagnostic test and shows the RNA of the virus in coronavirus. In other words, the PCR test is a test performed during the coronavirus process to show the identity of the virus in the body. PCR, which is also used for different diseases, can detect even a very small number of microbes in the body. The PCR test can also be called a molecular diagnostic test. The test can detect the presence of the virus in the body, as well as the antibodies the body produces in response to infection.

Which diseases are PCR tests used to diagnose?

The name of the PCR test has been heard recently for the screening of Covid 19, that is, the coronavirus. However, the PCR test is widely used not only in the coronavirus, but also in the detection of many viruses, parasites, microbes or bacteria in the body, genetic problems and paternity tests. Many disease agents can be detected early and quickly by PCR test.

How is the PCR test done?

In PCR tests, a swab sample is taken from the nose and throat by means of a thin cotton swab. In addition, sputum that comes out after coughing can also be taken as a sample. If it is used for coronavirus, it is more appropriate to take a sample from the throat or nose for PCR testing in the early stages of the disease. However, samples should be taken from airlines in the future. Because in the later stages of the disease, there may be no virus sample left in the throat or nose. The sample taken by the healthcare worker at the right time and accurately is placed in a special container and this sample is transferred to the test cartridge in the laboratory. After this step, the sample is automatically filtered. Then the DNA of the virus is released by ultrasonic waves. At this stage, DNA molecules are mixed with PCR agents. Real-time amplification and identification are then performed in the reaction tube. And then comes the conclusion stage. PCR; Denaturation, i.e. separation of two strands of DNA exposed to high temperatures, between 94°C-98°C, annealing between 37°C-65°C, attachment of synthetic oligonucleotides to target DNA (hybridization), and 72°C It consists of 3 stages, namely the elongation stages. The test is carried out by repeating these stages in a certain cycle and in a number of times. There are two types of applications in PCR tests. These are real-time PCR, that is, real-time PCR, and PCR with fast results. While real-time PCR results can be obtained in 1-3 hours, results can be obtained in 15 minutes to 1.5 hours for fast results. Denaturation, i.e. separation of two strands of DNA exposed to high temperatures, between 94°C-98°C, annealing between 37°C-65°C, attachment of synthetic oligonucleotides to target DNA (hybridization), and 72°C It consists of 3 stages, namely the elongation stages. The test is carried out by repeating these stages in a certain cycle and in a number of times. There are two types of applications in PCR tests. These are real-time PCR, that is, real-time PCR, and PCR with fast results. While real-time PCR results can be obtained in 1-3 hours, results can be obtained in 15 minutes to 1.5 hours for fast results. Denaturation, i.e. separation of two strands of DNA exposed to high temperatures, between 94°C-98°C, annealing between 37°C-65°C, attachment of synthetic oligonucleotides to target DNA (hybridization), and 72°C It consists of 3 stages, namely the elongation stages. The test is carried out by repeating these stages in a certain cycle and in a number of times. There are two types of applications in PCR tests. These are real-time PCR, that is, real-time PCR, and PCR with fast results. While real-time PCR results can be obtained in 1-3 hours, results can be obtained in 15 minutes to 1.5 hours for fast results. It consists of 3 stages: annealing at 37 °C-65 °C, that is, binding of synthetic oligonucleotides to the target DNA (hybridization) and elongation at 72 °C. The test is carried out by repeating these stages in a certain cycle and in a number of times. There are two types of applications in PCR tests. These are real-time PCR, that is, real-time PCR, and PCR with fast results. While real-time PCR results can be obtained in 1-3 hours, results can be obtained in 15 minutes to 1.5 hours for fast results. It consists of 3 stages: annealing at 37 °C-65 °C, that is, binding of synthetic oligonucleotides to the target DNA (hybridization) and elongation at 72 °C. The test is carried out by repeating these stages in a certain cycle and in a number of times. There are two types of applications in PCR tests. These are real-time PCR, that is, real-time PCR, and PCR with fast results. While real-time PCR results can be obtained in 1-3 hours, results can be obtained in 15 minutes to 1.5 hours for fast results. These are real-time PCR, that is, real-time PCR, and PCR with fast results. While real-time PCR results can be obtained in 1-3 hours, results can be obtained in 15 minutes to 1.5 hours for fast results. These are real-time PCR, that is, real-time PCR, and PCR with fast results. While real-time PCR results can be obtained in 1-3 hours, results can be obtained in 15 minutes to 1.5 hours for fast results.

Frequently asked questions about PCR testing

What are the advantages of PCR testing?

With the PCR test, people or carriers of coronavirus are identified, their isolation is cauterized, and in this way, a very important step is taken to control the epidemic. In addition, the PCR test is a test that gives results in a very short time. Since blood is not taken, it is an important advantage that it is performed painlessly.

Is the PCR test reliable?

PCR is an extremely reliable test method. This test allows to identify carriers that do not show symptoms especially in coronavirus. When carriers are detected, it will be possible to create a precautionary plan to control the coronavirus epidemic.

Who is PCR tested for?

Although the PCR test is performed on people who have symptoms of Covid 19, it can also be applied to those who do not have symptoms. Depending on the patient’s condition, samples are taken from the upper or lower respiratory tract.

Where is the PCR test done?

The PCR test is sampled in health institutions approved by the Ministry of Health, and the results are obtained in approved laboratories.

What should be considered when performing a PCR test?

For PCR testing, the sample must be taken at the right time and in the right way. Care should be taken to send the sample taken to the laboratory within the framework of hygiene rules and to apply all health measures during the test.

Are rapid diagnostic tests more reliable?

Although it is possible to get rapid results for coronavirus in rapid diagnostic tests, they may be less reliable than PCR tests. It was observed that the results of the people who had negative results 5-6 times in the rapid diagnosis tests were positive in the 7th test. For this reason, it is necessary to confirm with PCR even if the rapid diagnostic tests are negative, especially for those with coronavirus symptoms. At this point, it is very important to perform lung tomography and isolate the patient, if necessary.

How long does the PCR test take?

It is possible to get results within 1-3 hours from the PCR test. The results can be reported within 24, depending on when the samples are taken and the test is run.

Where is the PCR test used?

PCR; It is used to diagnose many viruses, bacteria and parasites such as genetic diseases, prenatal diagnosis, coronavirus, forensic medicine, cancer research, paternity tests, DNA analysis, HIV and Hepatitis B.

What is the difference between PCR test and antibody test?

One of the things to know about the antibody test is that it is not an antigen test. Antigen tests are tests that reveal whether the person is sick, that is, the presence of acute infection. Antibody tests, on the other hand, are intended to identify whether the person has had the infection before and whether they have become immune to the virus. In other words, it does not give information about whether the person is sick at the time of the test. The PCR test also gives the genetic information of the virus, the result of whether the coronavirus or a different virus has infected the patient. While the PCR method is infected, it gives results when the antibody of the disease is not formed. The antibody test measures the total IgG type antibodies formed by the body’s immune system against the SARS CoV-2 virus that causes Covid 19. In other words, it is a test that shows whether there is immunity to this disease. It is different from the test performed by taking a sample from the throat or nose, it is studied by taking blood from the arm. It is more reliable than the tests that work with blood taken from the fingertip. Although the PCR test takes about 40 minutes to work, the result is reported in 24 hours at the latest.

What does PCR positive mean?

A positive result in the PCR test means that the coronavirus has been infected with this disease. Thus, the person and those around him are isolated so that the risk of transmission of the coronavirus to other people can be reduced.

Why is antibody testing done?

Antibody tests have many uses. For example, the highest demand for tests comes from workplaces preparing for a return to normalcy. Large factories, banks, schools, chain brands and restaurants may request screening of employees before returning to work. Many companies are planning the return to work process by screening for infection immunity with this test. For example, antibody tests can be performed on advanced age and risk groups with chronic diseases, and individuals at risk of severe infection can be protected, or phase 1 period can be completed with workers with positive antibody tests. In addition, people who have not been able to see their family members with advanced age and chronic diseases during the pandemic process can learn their immune status with the test and want to see if they carry a risk for their loved ones.

Is the antibody test reliable?

The performance of all antibody tests is evaluated according to their sensitivity and specificity rates. A test sensitivity of 100% (definition of “correct positivity”) means that the test is 100% reliable if the patient’s test result is positive. The specificity of antibody tests is 99%, which indicates the “true negativity” rate of the test performed. All these values ​​increase in direct proportion to the increase in the number of people tested. It is clear that these new tests developed have high sensitivity and specificity in terms of reliability. 

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