PCR diagnosis of infections

PCR, or otherwise a polymerase chain reaction, is a method for laboratory diagnosis of various infectious diseases.

This method was developed by Cary Muillis back in 1983. Initially, PCR was used only for scientific purposes, but after a while it was introduced into the field of practical medicine.

The essence of the method is to identify the causative agent of infection in DNA and RNA fragments. For each pathogen, there is a reference DNA fragment that triggers the creation of a large number of its copies. It is compared with the existing database containing information on the structure of DNA of different types of microorganisms.

With the help of a polymerase chain reaction, it is possible not only to detect the infection, but also to give it a quantitative evaluation.

When is PCR used?

The analysis of biological material, carried out with the help of PCR, helps to detect various urogenital infections, including hidden ones, which do not show themselves as special symptoms.

This method of research allows us to identify the following infections in humans:

• herpes simplex virus of both types;
• HIV infection;
• gardnerellez ;
• chlamydia;
• ureaplasmosis;
• candidiasis;
• mycoplasmosis;
• trichomoniasis;
• papillomavirus infection ;
• as well as hepatitis B and C, tuberculosis, Helicobacteriosis, infectious mononucleosis.

When preparing for and during pregnancy, a woman must be assigned PCR diagnosis of various sexual infections.

Biological material for PCR research

To detect infections by PCR, the following can be used:

• urine, a swab from the cervical canal (in women), a swab from the urethra, secretions from the genitals - for testing for sexual infections;
• blood - for research on HIV infection and hepatitis C;
• A smear from the throat - for investigation of infectious mononucleosis.

Advantages and disadvantages of PCR diagnostics of infections

The merits of analysis for infection, carried out by the PCR method include:

1. Universality - when other diagnostic methods are powerless, PCR detects any RNA and DNA.
2. Specificity. In the study material, this method reveals a sequence of nucleotides typical for a particular pathogen of infection. Polymerase chain reaction makes it possible to identify several different pathogens in the same material.
3. Sensitivity. Infection when using this method is detected, even if its content is very low.
4. Efficiency. To identify the causative agent of infection takes quite a bit of time - only a few hours.
5. In addition, the polymerase chain reaction helps to detect not the reaction of the human body to the penetration into it of pathogenic microorganisms, but a specific pathogen. Due to this, it is possible to detect the patient's disease before it starts to manifest itself with specific symptoms.

The "minuses" of this diagnostic method include the need for strict adherence to the requirements for equipping laboratory rooms with high-purity filters, so that contamination of other living organisms taken for analysis of biological material does not occur.

Sometimes an analysis performed by PCR can give a negative result in the presence of obvious symptoms of a certain disease. This may indicate non-compliance with the rules for the collection of biological material.

At the same time, a positive result of the analysis is not always an indication that the patient has a particular disease. So, for example, after the treatment, the deceased agent for a certain time gives a positive result of PCR analysis.