Chlamydia in urine. Examination for chlamydia using the PCR method

34 541

As you know, every disease has its own, inherent only to it, signs. But it has nothing to do with chlamydia.
Chlamydia- this is a disease that does not have clear symptoms that are unique to it, and sometimes it is completely asymptomatic. And even if some are manifested, then most often they are similar to the signs of other STDs.
Therefore, laboratory research methods are decisive for making a diagnosis. Unlike many other diseases, the diagnosis of chlamydia is purely laboratory.

Who should be screened for chlamydia first?

• Men and women who have many sexual partners, especially casual ones.
• Persons whose sexual partners are found to have chlamydia, even in the absence of complaints and symptoms. After all, complications of chlamydia can develop even with its asymptomatic course. The risk of infecting a partner is about 90%.
• Women suffering from infertility for more than 2 years, even if the sexual partner is examined and healthy.
• Women with cervical erosion, cervicitis, inflammation of the ovaries (especially when planning pregnancy). Moreover, the vaginal smear may be normal.
• Women with a violation of the course of pregnancy: spontaneous miscarriage, premature birth, polyhydramnios, fever of unknown origin during this pregnancy.

What are they researching?
To detect chlamydia, it is necessary to make a sampling of the material. It can be a scraping containing cells of a diseased organ - the vagina, cervix, prostate secretion, scraping from the urethra, conjunctiva of the eye. Such material can also be blood, urine and semen in men.

What tests are prescribed for chlamydia and how useful can they be?
First, we will dwell on the possible methods of examination, and then we will conclude which of them are most preferable.

2. Immunocytological analysis - Direct immunofluorescence reaction (RIF or PIF).
This method involves the direct detection of chlamydia antigens. For this, the material obtained by scraping is treated with special antibodies that are directly treated with a fluorescent substance. These antibodies bind to specific chlamydia antigens. Then, with fluorescent microscopy, chlamydial inclusions in the cells are determined by a green or yellow-green glow.
The immunocytological method is used in both the acute and chronic phases of the disease.
A significant disadvantage of RIF is a large number of false negative and false positive results. False-negative results are most often associated with violation of the rules for sampling biological material. False-positive results may be due to combined infections of the urogenital tract, when other microbial flora is present along with chlamydia. Among other things, the RIF is very subjective, because. depends on the experience and personal assessment of the laboratory assistant. Therefore, RIF gives a very high percentage of false positive results and cannot be considered reliable. The disadvantage of RIF is also that it cannot be used to evaluate the results of treatment.
With urogenital chlamydia, the accuracy of the method is about 50%.

3. Enzyme immunoassay (ELISA).
ELISA is a method for indirect detection of bacteria, i.e. the pathogen is not detected directly, but specific antibodies (IgG, IgA, IgM) to it are determined. The method is based on the ability of the immune system to produce antibodies ( immunoglobulins, Ig) in response to the introduction of foreign agents.
The advantages of ELISA are that it allows not only to identify the causative agent of the disease, but also to determine at what stage it is (acute or chronic) and evaluate the effectiveness of the treatment. The advantage is also the automation of the method and the speed of its implementation.

How are the results evaluated?
When infected with chlamydia, specific antibodies appear on the 5-20th day of the disease. In this case, the appearance of each class of antibodies occurs at a certain stage of the disease.

• In primary infection, IgM appears first, then IgA, and lastly IgG.
• The very first after the primary infection (after 5 days) appear IgM, which protect the body from the possible spread of infection. They are markers of the acute stage of the disease. By the 10th day, the amount of IgM in the blood reaches a peak. Then their level begins to decrease, and IgA appear. For a short period of time, IgM and IgA antibodies can be detected in parallel. This period indicates the height of the infectious process.
• IgA can be detected 10 days after the onset of the primary symptoms of the disease. They protect the mucous membranes from the penetration of bacteria deep into the tissues. A high level of IgA in mucosal secretions indicates a well-functioning local immunity.
• Then, 15-20 days after the introduction of Chlamydia trachomatis into the body, IgG appears in the blood, and the level of IgA decreases.
• The acute primary process is characterized by a high level (titer) of IgM in combination with a low titer of IgG.
• With re-infection, there is a rapid increase in the titer of IgG and IgA and the almost complete absence of IgM.
• In the chronic course, specific IgG and A are detected, the concentrations of which do not change for a long time.
• When cured after 1.5-2 months, IgA and IgM are not detected in the blood, and IgG can persist for several years, but their level decreases by 4-6 times.
• Long-term detectable IgG indicates past chlamydial infection.
• With an exacerbation of chlamydia, the amount of IgA and IgG increases several times.
• The effectiveness of the treatment is determined by the presence of IgA. If IgA is detected in the blood 2 months after the course of treatment, this means that the infection has remained.

It should be noted that specific antibodies produced to chlamydia do not provide stable immunity against them.
The accuracy of this test for chlamydia is about 70%. This is due to the fact that antibodies to chlamydia can also be present in healthy people due to a previous illness, as well as be determined in respiratory and other types of chlamydial infections.

4. Polymerase chain reaction (PCR).
Using PCR, a specific site or DNA fragment of chlamydia is detected in the material under study, therefore, in comparison with other methods, it is impossible to confuse chlamydia with some other infection. It is effective in both acute and chronic phases of the disease. At the same time, very little material is needed for analysis, but the results are ready in 1-2 days.
For PCR research, the material can be scraping from the urethra or cervical canal, prostate secretion, urine sediment, scraping from the conjunctiva of the eyes, blood.
When diagnosing a primary infection, it is more informative to identify this infection in the places of initial localization, i.e. the material should be scrapings from the genital tract. False-positive PCR results may be in case of violation of the process of sampling, transporting the material and conducting the analysis itself.

Important! To assess the effectiveness of PCR treatment, the study cannot be carried out earlier than a month after the course of antibiotic therapy, because. you can get false positive results. This is due to the fact that when a DNA fragment of chlamydia is detected, it is impossible to assess how viable the microbial cell itself is. In this case, the viability of chlamydia, as well as the possibility of recurrence of the disease associated with it, is assessed using a microbiological method. If chlamydia is not viable, then despite the presence of a DNA fragment, microbial cells will not grow in cell culture.
To date, the accuracy of this method is the highest - up to 100%.
This method is recommended as the preferred method in the diagnosis of chlamydial infection.

5. Microbiological examination (cultural method) with the determination of sensitivity to antibiotics.
The essence of this method is that the studied material is sown on a special medium and grown. Then, the pathogen is identified by the nature of growth and other signs. The cultural method is the most sensitive, it allows not only to identify viable chlamydia, but also to select an antibiotic to which this microorganism is sensitive.
Scraping from the urethra, cervix, prostate secretion, scraping from the conjunctiva of the eye can serve as material for research.
One month before the study, antibiotics should not be used.
Microbiological examination is preferable to carry out in the following cases:

• To evaluate the effectiveness of the antibiotic treatment.
• To detect sensitivity to antibacterial drugs.
• To detect chlamydia in people with immunodeficiencies (HIV infected, cancer patients after radiation and chemotherapy, people receiving immunosuppressants, etc.).

The disadvantages of the cultural method for diagnosing chlamydia are the complexity, high cost and duration of the study. It also requires special laboratory equipment and very high qualification of personnel. Moreover, this method, like no other, requires impeccable compliance with the rules for the collection of material, transportation and storage.
The actual term for obtaining results by this method is at least seven days.
The detection rate of chlamydia during sowing is up to 90%.

6. Express diagnostics.
All methods of rapid diagnosis of chlamydia are based on enzyme-specific reaction and immunochromatography. For this, special kits for express diagnostics are used, which allow you to visually evaluate the results in 10-15 minutes. This is a very fast and convenient method, but its accuracy is only 20-25%.

Conclusions.

• There is no single method that would detect chlamydia in 100% of cases. Therefore, in most cases laboratory diagnostics must include a combination of at least two methods.
• The most sensitive tests for chlamydia are PCR (DNA - diagnostics) and microbiological analysis. They are the "legal standard" for diagnosing chlamydia.
• In the case of primary infection, one PCR test is usually sufficient before the use of antibiotics.
• In chronic processes - PCR or microbiological test, or RIF + ELISA.
• With the probability of the transition of the pathogen into the L-form - ELISA.
• Microbiological examination is ideally used to evaluate the effectiveness of treatment. If it is impossible to conduct it - PCR + ELISA.
• To determine the stage of the disease - ELISA.
• In patients with immunodeficiencies, ELISA is not informative; ideally, a microbiological method should be used.
• You should not rely too much on the results of determining the sensitivity of chlamydia to antibiotics. After all, as you know, microorganisms behave differently in a test tube (in vitro) and in a living organism (in vivo).

A smear for chlamydia by PCR should be regularly taken by people who are promiscuous. intimate life. The analysis is also carried out in case of detection of a disease in a sexual partner or the appearance of unpleasant symptoms. Examination of pregnant women is mandatory.

Characteristics of the PCR method

This is the most informative research method, on the basis of which the final diagnosis is usually made. Other methods require additional confirmation. PCR analysis is an accurate method, it is prescribed by most doctors, and it is convenient for the patient.

The polymerase chain reaction is the latest development in molecular medicine. This study is based on a series of actions during which the infectious agent is detected and identified. Despite the complexity in execution and the detailed study of the material, the result can be obtained in a few days. You should not use express diagnostics, it does not always make it possible to detect chlamydia.

You need to know how this analysis is taken. The test will require blood, urine, or urethral discharge. Preparation for the fence has its own characteristics. It is recommended to take blood for chlamydia on an empty stomach. You can not drink water and use chewing gum. Otherwise, the PCR analysis may give an incorrect result. Men are tested for:

• smear from the urethra;
• seminal fluid.

Patients must abstain from intimacy 24 hours before delivery and pre-ejaculation. It negatively affects the results of the study. There are other rules that must be followed.

Urine for PCR analysis can be collected both at home and in the laboratory. In the first case, it is necessary to urinate into a sterile container immediately after waking up. For detection, the first portion of urine is used. The received material must be delivered to medical institution within 3 hours. A positive result of the analysis is an indication for additional testing. An integrated approach allows you to determine the form and severity of the disease.

How is the procedure performed

The procedure for passing the analysis for men and women is different. Most of all, this concerns the process of collecting secretions from the genital organs. In women, the swab is taken from the vagina or urethra. In order for the study to give the correct result, it is recommended:

Donate blood. This type of study does not harm the developing child and allows you to get a complete picture of the disease. The same method is used for chronic chlamydia. It is more difficult to determine the infection in the urine.

PCR analysis in men involves taking a smear from the urethra or seminal fluid. Preparation is not much different from that of women:

1. You should refrain from urinating for 3 hours before donating the material. This will ensure the reliability of the result of the study of the urethral smear.
2. If it is necessary to take seminal fluid, the last sexual intercourse should take place no later than one day before visiting the laboratory.
3. Do not use pills and gels to stimulate an erection. These drugs adversely affect hormonal background the body of a man, because of which the purity of the seed is violated and the result of the analysis may be incorrect.

Decryption features

Processing the material takes no more than half an hour. In the course of the study, DNA fragments are repeatedly copied. The nucleotide chain is formed under the influence of the enzyme - polymerase. To start a reaction, a substance needs a launch pad, which is catalyzed by synthetic oligonucleotides. The polymerase sequentially adds nucleotides to form DNA templates. Thus, 2 new fragments are produced in one temperature cycle. In 25–35 cycles, billions of copies of a piece of DNA accumulate in a test tube.

Deciphering the results takes about 8 hours. However, to increase the reliability, many experts recommend to donate blood in parallel for the presence of antibodies to chlamydia. This will help determine the stage and nature of the course of the disease and select the most effective therapeutic regimen. The norm is the result when chlamydia trachomatis is absent in the obtained sample. Material for PCR analysis must be taken by both partners, otherwise the treatment will be useless.

Disadvantages and advantages of the method

One of the main advantages of PCR diagnostics is high accuracy. The positive characteristics include the fact that on the basis of its results it is possible not only to detect the presence of chlamydia in the body, but also to detect other STIs. To perform the study, minimal amounts of material are required; a blood test for chlamydia can be performed in each laboratory.

The disadvantage is the frequent receipt of a false positive result. This is due to many factors, the elimination of the influence of which is not always possible. Therefore, if chlamydia is detected in a smear, serological tests should be used. A negative result also does not always indicate the absence of an infectious agent.

The final diagnosis is based on the results of laboratory tests, examination of the patient and the clinical picture of the disease.

Chlamydia belongs to the category of infections that are discovered by chance. This is due to the asymptomatic course, in which the disease still affects internal organs. In order to avoid the development of dangerous complications, it is necessary to undergo an annual examination. An indication for PCR is the presence of indirect signs of the disease, because timely detection and treatment of chlamydia leads to complete recovery.

Sexual infections, including chlamydia, can not always be diagnosed by external examination. The symptoms and signs of such diseases are very similar and, if the diagnosis is not accurate enough, a bacterial infection can be confused with a viral or fungal one. The result of such an oversight can be deplorable, and therefore, even in the presence of signs typical of diseases, laboratory tests are used.

Chlamydia can be diagnosed by polymerase chain reaction

What is PCR

The essence - this is how the name of the analysis is deciphered - consists in repeated copying of DNA fragments obtained from biomaterial that meet certain requirements. This method is used not only to detect chlamydia in a smear or blood in men and women (including pregnant women), but also for other equally important studies:

• establishment of kinship between people;
• identifying predisposition to diseases;
• allocation of new genes (mutated, for example);
• cloning of genes with certain characteristics.

The PCR method allows you to establish kinship

The described reaction requires relatively small material costs, and also takes a short time period to obtain a result. This is what made it possible to use the polymerase chain reaction in the course of an ordinary, widespread diagnosis of genital infections in men and women.

Today, more than 90% of patients are referred for PCR if chlamydia is suspected. Thanks to this, it is possible to identify the pathogen even with a slight degree of organ damage and against the background of a complete absence of symptoms.

Advantages of the method

Since chlamydia in most cases proceeds latently, diagnostic methods that can identify the pathogen even in the absence of visible signs of the disease are of particular value. Determination of the presence of a pathogen by a direct method is the first advantage of any analysis for STIs. This characteristic is present in the PCR method, moreover, to the same extent for all types of biological material: blood, ejaculate, vaginal or urethral secretion.

When performing PCR on chlamydia, both blood and other materials can be used.

The second significant advantage of the method is a very high degree of specificity. While other tests may give an erroneous result due to the presence of foreign microorganisms, PCR, if chlamydia is suspected, will detect only chlamydia.

The third advantage of the assay is its very high sensitivity. If for the microscopic determination of the presence of chlamydia in a scraping or blood, it is necessary that at least 103 pathogenic cells be present in the material, then PCR detects infectious agents at their concentration from 10 cells.

Despite the use of high-tech research, the results of the PCR analysis are ready on the 2nd or 3rd day after their delivery.

Preparation for analysis

Despite the fact that PCR for chlamydia is a diagnostic method that is very rarely erroneous, it must be prepared very carefully to reduce the likelihood of a false result.

Medications can skew test results

First of all, it is necessary to stop taking any antibiotics, except for those prescribed by the doctor. This must be done at least one month before the test. At the time of sampling, it is worth informing the laboratory assistant about all the medicines that were taken the day before.

If you plan to take a scraping from the urethra or a swab from the vagina, you must abstain from sex for 5-6 days before the procedure, even if you intend to use a condom. The seminal fluid and the lubricant produced can change the composition of the secretion on the mucous membranes of the genital tract, as a result of which the analysis may give a false positive or false negative result. For the same reason, men are not recommended to empty their bladder for 3-4 hours before taking a smear.

Unlike men, in women, urination has little effect on traces of chlamydia, PCR in them may give an incorrect result on the eve of menstruation or if douching was performed before the material was taken. That is why women should refrain from irrigating the vagina, and it is recommended to take a smear test on the 3rd or 4th day after the end of bleeding.

Sexual contact should be avoided before testing, even with contraceptives

Donating blood for PCR testing is recommended on an empty stomach. In order for this condition not to cause difficulties, you need to visit the treatment room or laboratory in the morning.

The day before, the doctor will explain how to take this or that analysis, which will be investigated by the polymerase chain reaction method.

How is the collection of material

Thanks to high level specificity, the molecular (polymerase) reaction does not require the collection of a large amount of biological material. The source of information about the presence of chlamydia in the body is discharge from the genital organs, but blood is most often used.

To detect chlamydia in a man, it is necessary to do a smear from the urethra

Taking a smear for chlamydia using the PCR method is shown, first of all, to the representatives of the stronger sex. In men, the concentration of pathogens in the ejaculate and on the urethral mucosa is always higher than in women. In addition, the analysis cannot be affected by cyclic hormonal fluctuations, which very often occurs in women. Representatives of the weaker sex, especially those in a state of pregnancy, as well as during menstruation or a few days before its onset, do not donate a smear for research, but blood.

The study of a PCR smear for chlamydia begins with the collection of material. They do this in the office of a urologist for men or a gynecologist for women. In this case, the urologist uses special devices - spoons or probes. After introducing them into the urethra, the doctor, gently turning the instrument around its axis, slowly removes it. After that, the probe is placed in a test tube filled with the so-called transport medium. In a similar way, the discharge of the separated substance from the vagina in women occurs.

In some cases, men do not take a swab from the urethra, but the first portion of urine after prostate massage, or saliva, or ejaculate.

For PCR, blood is taken from a vein

Blood for the diagnosis of chlamydia by PCR is taken in the treatment room or in the laboratory. In women and men, the procedure is the same: on the elbow bend, the laboratory assistant finds a large vein and inserts a special needle into it. After filling a special test tube, it is closed with a tight stopper and immediately sent to the laboratory.

Who needs to be tested

Referral for PCR analysis is received by patients who have obvious or erased signs of chlamydia. They may be:

• chronic inflammatory diseases of the genitourinary system of unknown origin;
• pain in the groin and lower abdomen, radiating to the lower back, in men and women;
• joint pain of unknown origin;

PCR may be required to diagnose various diseases of the urinary system

• chronic bacterial conjunctivitis;
• secondary infertility.

It is also used to monitor the healing process to ensure complete eradication of the bacterium, along with culture diagnosis.

The value of the PCR method cannot be exaggerated, since in addition to the possibility of detecting chlamydia, which is difficult to diagnose, it allows you to detect many other pathogenic microorganisms and pathological changes in the body. Despite the fact that this analysis in most clinics is carried out on a paid basis, its popularity is growing every year.

Additionally, the doctor will tell you about the PCR analysis for chlamydia in the video:

PCR analysis is one of the most effective methods for diagnosing chlamydia. This infectious disease is difficult to detect. It often proceeds asymptomatically, in other cases, the symptoms of the disease are blurred, resembling a host of other pathologies. However, chlamydia is fraught with serious complications that can appear several years after infection. In men, prostatitis is often detected, in women - infertility, cervical erosion and pelvic inflammatory disease. For this reason, timely and accurate diagnosis of chlamydia is extremely important.

What is PCR analysis, how does it work and in what cases is it prescribed?

Material for this study can be taken directly from the source of infection, with chlamydial infection, these include:

• vagina;
• Cervix;
• urethra;
• sperm;
• prostate secret.

Urine or blood can also be taken for PCR research.

During the study, sections of DNA and RNA of the desired pathogens are isolated, which enter into a specific polymerase reaction, which causes their rapid growth and development, which facilitates their detection.

This is an absolutely painless technique that does not require special preparation from patients. On the other hand, it does not require significant efforts from physicians either: within two to three days after sampling, one can obtain reliable information about the presence or absence of Chlamydia trachomatis microorganisms in a patient.

PCR is able to detect the presence of even single chlamydia in the assays. During the study, special conditions are created for the growth and development of chlamydia DNA in the selected material - this is a polymerase reaction, a chain chemical process gave the name to the method itself. Then, special analytical markers are added to the sample, which indicate the presence or absence of chlamydia DNA in the sample.

In most cases, this research method is assigned:

• during pregnancy;
• when chlamydia is detected in a sexual partner;
• with infertility with no identified cause;
• with symptoms of chlamydia.

In addition to chlamydia, PCR is prescribed for the following diseases:

To date, almost all pregnant women are recommended to undergo a PCR test for chlamydia. Why is this happening? Chlamydia is a dangerous disease that can be transmitted from mother to child during physiological childbirth. At the same time, chlamydia is in many cases asymptomatic, for this reason, a pregnant woman may not even suspect that she has a similar infection.

If a chlamydial infection is found in a pregnant woman's smear, the woman will need a rather long treatment, which requires the use of antibiotics. Nevertheless, in the arsenal of modern doctors there is a sufficient number of drugs that are effective and safe for mother and child. The doctor who leads the pregnancy will tell you in detail how to take PCR for chlamydia during the bearing of a child.

Despite all the undeniable advantages of this method, it still has a number of significant disadvantages:

How to prepare for the analysis correctly and how to decipher the results of the analyzes?

This type of research does not require special preparation measures, the material sampling is quick and painless. However, compliance simple rules will help to obtain a reliable result of the analysis. Here are these simple steps to prepare for a PCR study:

If you need to donate blood for analysis, follow these rules:

• blood for PCR is taken on an empty stomach: before taking biological material, you can’t eat, including chewing gum, you can’t even drink water;
• a day before the analysis, it is desirable to exclude fatty and fried foods from the diet;
• must also refrain from taking any medicines, of course, if they are not vital.

Urine may be required for analysis, it is collected in the following way:

Violation of these rules can lead to a false negative result of the study, which in turn complicates the appointment of treatment and may lead to the development of complications.

Only a professional doctor can make a correct diagnosis and prescribe adequate treatment for chlamydia, but a person without medical education can understand the results of the analysis in general terms. Private clinics in most cases do not comment on the indicators found.

A "negative" result indicates the absence of the desired microorganism in the material provided for the study. However, PCR analysis is not the ultimate truth. If the patient has clear signs of chlamydia with "clean" tests, this is a reason for re-examination with the connection of other methods.

A “positive” answer indicates the presence of a particular pathogen in the provided sample. However, this does not always confirm the presence of an infectious process. PCR analysis gives a qualitative display of the composition of the microflora, which can be misinterpreted.

So, for example, some bacteria and other microorganisms can be constantly present in the microflora of the vagina in a small amount, without causing inflammation. The development of the disease can cause a sharp increase in the number of these microorganisms. That is, not only the presence of certain microorganisms is important, but also their number.

Chlamydia is a disease that is difficult to diagnose and even more difficult to treat. To identify the disease, it is necessary to connect the most modern and effective methods which include PCR diagnostics.