Serological diagnosis of syphilitic infection. Modern laboratory methods and algorithms for the diagnosis of syphilis. How to interpret syphilis tests

Taxonomy of Borrelia, Leptospira and Treponema, and the names of diseases caused by them.

Family: Spirochaetaceae

Genus: Borrelia

Species: B. recurrentis - the causative agent of epidemic relapsing fever.

Genus: Treponema

Species: T. pallidum - the causative agent of syphilis

Genus: Leptospira

Species: L. Icterohaemorrhagiae - the causative agent of leptospirosis

Microscopic diagnosis of syphilis.

Dark-field microscopy: before the study, tissue fluid is taken from the bottom of the ulcer or a punctate of the lymph node. A preparation of a crushed drop is prepared: a drop of the test material is applied to the middle of the glass slide, the drop is covered with a cover slip so that there are no air bubbles. Positive result: treponemas with uniform 8-12 large curls are found on microscopy. They are characterized by smooth rotational-translational, pendulum-like and flexion movements. When stained according to Romanovsky-Giemsa: the causative agent of syphilis turns pale pink, other treponemas turn reddish-violet.

Reactions used in the serodiagnosis of syphilis. General characteristics of each of them.

RSK(Wasserman reaction): Components: 1 system - patient's serum, diagnosticum, complement, CNI; 2 system - hemolytic serum and a suspension of sheep erythrocytes. 1 system is prepared, incubated at 37C for 1 hour. A second system is added, incubated at 37C for 1 hour. A positive result is the absence of hemolysis.

RPGA: Components: CNI, patient's serum, erythrocyte diagnosticum. Serum dilutions are prepared, diagnosticum is added, in a thermostat for 24 hours 37C. Floor. result: umbrella.

ELISA: Components: patient serum, diagnosticum, conjugate, chromogenic substrate. The diagnosticum is connected with the plastic of the well of the tablet, diluted serum, conjugate and substrate are added. Floor. result: a change in the color of the substrate.

Indirect RIF: AG is applied to a glass slide - pale treponema (Nichols strain). The smears are air-dried and fixed in acetone for 5 minutes. The patient's serum is depleted with a suspension of non-pathogenic treponemas of the Reiter strain or diluted 1:200, then applied to the prepared preparations. Keep in a humid chamber at 35C for 30 minutes (1 phase). The smears are washed for 10 minutes in ICN and dried. Next, a drop of fluorescent serum against human globulin is applied to the preparation and incubated in a humid chamber at room temperature for 30 minutes (phase 2). The smears are washed with ICN and dried. viewed under a fluorescent microscope. Positive reaction: green glow.

Flocculation reaction on glass: blood plasma or unheated serum is mixed with a non-specific lipid antigen for several minutes on a glass slide. Positive result: enlarged antigen particles (flocculate) are visible under low magnification.

Serodiagnosis of syphilis using RPHA.

Components: CNI, patient's serum, erythrocyte diagnosticum. Serum dilutions are prepared, diagnosticum is added, in a thermostat for 24 hours 37C. Floor. result: umbrella.

Serodiagnosis of syphilis using ELISA.

Components: patient's serum, diagnosticum, conjugate, chromogenic substrate. The diagnosticum is connected with the plastic of the well of the tablet, diluted serum, conjugate and substrate are added. Floor. result: a change in the color of the substrate.

Serodiagnosis of syphilis using RSK.

Wasserman's reaction: you can use the patient's blood serum and cerebrospinal fluid (at the stage of neurosyphilis). As a diagnosticum - treponemal or cardiolipin antigen. Components: 1 system - patient's serum, diagnosticum, complement, CNI; 2 system - hemolytic serum and a suspension of sheep erythrocytes. 1 system is prepared, incubated at 37C for 1 hour. A second system is added, incubated at 37C for 1 hour. A positive result is the absence of hemolysis.

Methods of microbiological diagnostics of leptospirosis.

Bacterioscopic method: prepare a preparation of a crushed drop, study it in a dark-field microscope: movable thin threads with bends at the ends (secondary curls) - in the form of a bracket or the letter S.

Bacteriological method: material - blood, urine, cerebrospinal fluid. The material is inoculated (3-5 test tubes) in a water-serum medium, Fletcher's medium, Potato. Incubated up to 30 days at 28-30C in an atmosphere of CO 2 . To detect the growth of leptospira, 10 days after inoculation, material is taken from the test tube, a preparation of crushed potassium is prepared and studied under a dark-field microscope. From the test tube where the growth of leptospira was found, they are subcultured into 3 test tubes with fresh nutrient medium, incubated for 7-10 days, the temperature is the same. For differentiation, a bicarbonate test is carried out, hemolytic activity, phospholipase activity are determined. Identified by antigenic structure using agglutinating sera.

biological research: Guinea pigs are injected intraperitoneally with 1 g of the test material and observed for a month, noting the temperature and body weight, the appearance of jaundice and hemorrhages, as well as the death of the animal.

Serological study: AT in serum appear from 2 weeks. Use the reaction of microagglutination and lysis of leptospira. The patient's serum is diluted twice from 1:100 to 1:1600. 0.2 ml of diluted serum and the same amount of a live culture of Leptospira strains are added to a number of test tubes. Incubate for 1 hour at 37C. A crushed drop preparation is prepared from the contents of each test tube and microscoped. Antibodies in the serum of the first dilutions cause lysis - dissolution or granular swelling of leptospira. In subsequent dilutions - agglutination - agglomerates in the form of spiders. Diagnostic value has a positive reaction in a dilution of 1:400 and above.

1. Potekaev N.N., Frigo N.V., Almazova A.A., Lebedeva G.A. Epidemiology of syphilis in modern conditions. Clinical dermatology and venereology. 2015;1:22-34.
2. Larsen SA, Steiner BM, Rudolph AH. Laboratory Diagnosis and Interpretation of Tests for Syphilis. Clin Microbiol Rev 1995 Jan;1-21.
3. Coles AC. Spirochaeta pallida. Methods of examination and detection, especially by means of the dark-ground illumination. Br Med 1909;1:1117-1120.
4. Kellogg, DSJr, Mothershed SM. Immunofluorescent detection of Treponema pallidum: a review. JAMA 1969;107:938-941.
5. Mullis KB. Specific synthesis of DNA in vitro via a polymerase catalyzed chain reaction. Meth Enzymol. 1987;155:335.
6. Centurion-Lara A. Detection of Treponema pallidum by a sensitive reverse transcriptase PCR. J Clin Microbiol. 1997;35;6:1348-1352.
7. Wassermann A, Neisser A, Brück C. Eine serodiagnostische Reaktion bei Syphilis. Dtsch Med Wochenschr. 1906;32:745-746.
8. Pangborn MC. Cardiolipin and its application in a chemically purified antigen for the serodiagnosis of syphilis. Proc N Y State Assoc Public Health Lab. 1946;26(1):26-29.
9. Pangborn MC. A study of the composition of cardiolipin. FedProc. 1946;5(1 Pt 2):149.
10. Dmitriev G.A., Bragina E.E. Modern methods of laboratory diagnosis of syphilis. Part I Bulletin of dermatology. 1996;2:29-33.
11. Dmitriev G.A., Bragina E.E. Modern methods of laboratory diagnosis of syphilis. Part II. Bulletin of dermatology. 1996;3:33-38.
12. Nonspecific positive results of serological tests for syphilis. Quantitative modifications of modern serological tests. Guidelines. M. 1990.
13. Order of the Ministry of Health No. 87 of the Russian Federation of March 26, 2001 "On improving the serological diagnosis of syphilis."
14. Russian Society of Dermatovenerologists. Federal clinical guidelines for the management of patients with syphilis. M. 2013.
15. Lyakhov V.F., Borisenko K.K., Potekaev N.S., et al. Dynamics of treponema-specific immunoglobulinemia in early forms of syphilis. Bulletin of dermatology. 1990;8:38-42.
16. Kiseleva G.A., Tkachev V.K., Bednova V.N., et al. Comparative study of the sensitivity and specificity of three enzyme immunoassays designed to detect class M immunoglobulins to the causative agent of syphilis. Bulletin of dermatology. 2000;4:6-10.
17. Ermatova F.A. Determination of specific class M immunoglobulins for early diagnosis of syphilis (clinical and laboratory study): Dis. … cand. honey. Sciences. M. 2014.
18. Mardanly S.G., Arsenyeva V.A., Aniskova I.N., Zhigalenko A.R. Domestic test system "Line-Blot Syphilis-IgM" for the detection of IgM antibodies to Treponema pallidum by linear immunoblotting Clinical dermatology and venereology. 2013;5:35-38.
19. Guseva S.N. The use of the IgM-RIFabs test in the examination of pregnant women for the activity of syphilitic infection. Russian journal of skin and venereal diseases. 2004;6:60-63.
20. Ovchinnikov N.M., Bednova V.N., Delektorsky V.V. Laboratory diagnosis of sexually transmitted diseases. M. 1987.
21. Lee K, Park H, Roh EY, Shin S, Park KU, Park MH, Song EY. Characterization of sera with discordant results from reverse sequence screening for syphilis. Biomed Res Int. 2013;2013:269-347.
22. Binnicker MJ. Which algorithm should be used to screen for syphilis? Curr Opin Infect Dis. 2012 Feb;25(1):79-85.
23. Castro A, Jost H, Cox D, Fakile Y, Kikkert S, Tun Y, Zaidi A, Park M. A comparison of the analytical level of agreement of nine treponemal assays for syphilis and possible implications for screening algorithm. BMJ Open. 2013 Sep 19;3(9).
24. Park IU, Chow JM, Bolan G, Stanley M, Shieh J, Schapiro JM. Screening for syphilis with the treponemal immunoassay: analysis of discordant serology results and implications for clinical management. J Infect Dis. 2011 Nov;204(9):1297-1304.

Russian National Research Medical University. N.I. Pirogova

Department of Dermatovenereology, Faculty of Pediatrics

Report on the topic: Laboratory methods for diagnosing syphilis

Completed by: Student 440 in groups

Faculty of Pediatrics

Seranov Igor Anatolievich

Non-treponemal studies

Treponemal studies

Complex for conducting serological reactions

Wasserman reaction

Immunofluorescence reaction

immune adhesion reaction

Treponema pallidum immobilization reaction

Treponema pallidum adsorption immunofluorescence reaction

Hemagglutination reaction

Linked immunosorbent assay

polymerase chain reaction

All serological research methods that are used today are conditionally divided into two types: non-treponemal, qualifying (NTT) - and treponemal, which confirm the presence of the pathogen (TT). Syphilis is very difficult, the clinic is very blurred and does not always manifest itself, therefore, several serological tests are used at once to make the correct diagnosis. With visual confirmation of the presence of pale treponema in the taken material (using a microscope), the diagnosis is made immediately, and other tests are rarely performed.

Non-treponemal studies(tests) - NTT are so-called screening studies, they are not very expensive and with their help you can examine a fairly large number of patients, moreover, the results of many tests are ready very quickly. But with a false course of the disease, with low sensitivity, such tests are impractical, and a 100% result cannot be obtained.

When conducting non-treponemal tests in the material being examined, antibodies are detected that react with cardiolipin - lecithin antigen. One of the first tests was a method based on the immunological Bordet-Jangu reaction, where the liver extract of a newborn child who died of syphilis acted as an antigen. Today, when conducting such tests, the antigen is lecithin, cholesterol and cardiolipin.

Abroad, in particular in the USA, 4 non-treponemal methods are used, which are divided into two types: methods that allow you to visually determine the results of the reaction (RPR and TRUST) and methods for microscopic reading of the results (USR and VDRL).

Non-treponemal diagnostic methods include indirect linked immunosorbent assay using cardiolipin as antigen. In our country and in the CIS countries, the reaction of plasma with inactivated serum (MR) and the reaction in which the compliment is associated with cardiolipin (RCC).

All non-treponemal diagnostic methods are very similar to each other. They all have a low cost, they are simple and quick to carry out. These types of tests are not suitable for detecting the disease at the primary stage and for syphilis that occurs secretly (latent form of syphilis). Antibodies that are determined by a non-treponemal test appear about a month after infection with treponema. In most cases, in patients who have been treated for the primary stage of syphilis, non-treponemal tests are negative for about a year.

Treponemal studies(tests) - TTs are much more expensive, the technique is very complex and they are used to confirm the positive results that have been obtained in non-treponemal studies.

As we said above treponemal methods used to confirm the presence of pale treponema in the body, which was detected using non-treponemal tests. They are also carried out if the tests performed did not give a positive result, but the clinic suggests the presence of a disease. After the complete cure of syphilis, more than 80% of those cured have a positive reaction when conducting treponemal tests for several more years, and for some - for life. Based on this, treponemal tests are not used for preventive examinations in people who have completed a full course of treatment.

Scientific research in the field of immunology and molecular biology continues constantly and with the help of the latest technologies, more and more new tests for the diagnosis of syphilis are emerging, which are firmly in the lead. One of these tests, which has become firmly established in practice - enzyme immunoassay (ELISA), and many research methods are under development.

That serological testing complex, which is carried out in Russia, includes a comprehensive conduct of serological reactions:

standard serological reactions -

complement fixation reaction (Wassermann reaction),

reaction with treponemal antigen and reaction with cardiolipin;

group treponemal reactions -

immunofluorescence reaction (RIF)

immune adhesion reaction (RIP);

species-specific protein treponemal reactions -

treponem immobilization reaction (RIT),

RIF - abs and its variants (IgM-FTA-ABS, 19S-IgM-FTA-ABS),

reaction of passive hemaglucination of treponems (TPHA).

If serological tests are used in combination, this will make it possible to identify the disease in the early stages of the disease.

The Wasserman reaction is a method of complement fixation. To carry out the reaction, extracts are used as an antigen, which are made from pale treponemas (specific antigens) and cardiolipin is an extract prepared from the heart muscle of a bull (non-specific antigens). The more pale treponemas are observed in the test material, the greater the degree of the disease and evaluate the degree with pluses:

1) - negative; 2) + doubtful; 3) ++ weakly positive; 4) +++ positive; 5) ++++ strongly positive.

Wasserman reaction (Complement fixation reaction) without fail, they are carried out together with sedimentary reactions - Sachs - Vitebsky and Kahn. The immunological nature of the reactions is, in general, the same as that of the Wasserman reaction, but these reactions require more saturated antigens, which, when reacted with serum reagins, give a greater precipitate. Seronegative primary syphilis is diagnosed if standard serological tests are negative. Detection of syphilis Wasserman reaction is effective in seropositive secondary syphilis, here the test results are 100% correct. At the tertiary stage of active syphilis, the results are correct in more than half of the patients, and in the last stages of syphilis, with damage to internal organs and systems, the results are correct in half of the patients. At patients with early congenital syphilis, serological tests give a positive result almost always, and in patients with late congenital syphilis - in almost 80% of cases.

The principle of RSK is that the reagins found in the blood serum of patients with syphilis have the ability to enter into compounds with various antigens. The resulting complexes sort the complement introduced into the reaction. A hemolytic system (a mixture of ram erythrocytes with hemolytic serum) is used to indicate the reagin–antigen–complement complex. In the presence of the complex, erythrocytes precipitate. Which is noticeable to the naked eye. The severity of hemolysis is indicated by the doctor with the keys: sharply positive 4+, positive 3+, weakly positive 2+ or 1+ and negative. In addition to a qualitative assessment of these reactions, there is also a quantitative one, which is important in the diagnosis of certain stages of syphilis and in monitoring the effectiveness of therapy.

Immunofluorescence reaction (RIF) It is based on the detection of antibodies that are labeled with a special fluorescent solution in order to detect antibodies associated with the antigen in the violet rays of a quartz lamp. This reaction is highly sensitive and helps to identify the disease at the primary stage of seronegative syphilis. It is also this test that helps to identify the disease in patients in whom the disease is latent or in the late stages. There are several types of such reactions, and RIF-200 is the most highly valued, with which you can detect latent syphilis and recognize non-specific results of CSR. But, despite the high rates of RIF-200, the diagnosis is made after all clinical tests have been carried out. RIF is not suitable for monitoring patients after complete treatment, as it is rather slowly negative at the stage of treatment.

Immune adhesion reaction (RIP). This reaction is based on the adhesion of treponemas, which are sensitized by serum, to erythrocytes and their precipitation. The results are evaluated according to the following table:

Negative - 0-20%

Doubtful-21-30%;

Weakly positive - 31-50%;

Positive-51-100%.

In all respects, RIP is very similar to RIF and RIT. This reaction is carried out in several cases, if syphilis is not confirmed on the basis of clinical manifestations, anamnesis, laboratory tests, to control the disease after receiving the necessary treatment and to confirm the results of CSR.

Treponema pallidum immobilization reaction (RIT) Once in an environment where there are immobilizins of the test serum and active complement, pale treponemas lose their mobility. This is the basis of this reaction. RIT is very specific and is used to detect latent syphilis, to diagnose pregnant women in whom syphilis is suspected, and many other cases in which standard serological tests are of little specificity. The big disadvantage of this reaction is that it is very expensive and it is a very complicated process to carry out. The results are read according to the percentage data of immobilization of pale treponemas:

Negative - up to 20%; -doubtful -21-30%; -weakly positive -31-50%; -positive -51-100%.

Due to the fact that immobilisins appear in the blood later than other antibodies, the reaction becomes positive a little later than with other reactions. At the initial stage of infection, as a rule, a negative or weakly positive reaction is observed. At the secondary stage of syphilis, although the appearance of immobilizins in the patient's blood serum is observed up to 60%, the reaction is positive in almost half of the subjects. With a recurrence of the secondary stage of syphilis, RIT is positive in almost 90% of patients. At the tertiary stage of the development of syphilis, with damage to internal organs, including the nervous system, when the Wasserman reaction gives negative results, the immobilization reaction of pale treponema is positive in almost 100% of patients. At an early stage of congenital syphilis, the reaction has a positive result in almost all patients, and at a late stage of congenital syphilis - in almost 100% of patients. Seropositive latent syphilis is confirmed only after RIT, which is carried out after obtaining positive results during other serological tests. RIT is not used to control the disease in patients who received the necessary treatment.

Treponema pallidum absorbance immunofluorescence test (FTA-ABS).If the reaction is carried out for a patient who has syphilis and has not been treated, then this reaction always gives a positive result. There is also a high probability of detecting an infection using FTA-ABS at the very beginning of the disease.. The reaction has great sensitivity and specificity. For the diagnosis of latent syphilis and in cases where several tests have already been performed and they have shown a negative result, but the clinic speaks of infection with pale treponema, in such cases the diagnosis is often made based on the results of FTA-ABS. Literally a week after pale treponema entered the body, specific IgM antibodies begin to be produced, which eventually cease to appear and after 2 years are no longer detected. In order to understand whether the proposed treatment is effective, special tests are carried out that determine the specificity of these antibodies. There are several such tests today, but they are too expensive to conduct, so these tests are not performed for most patients.

Hemagglutination reaction, which determines specific antibodies to pale treponema (micro-TPHA). For this reaction, treponemas serve as an antigen, so this reaction is very specific and gives true results in most cases.

Enzyme immunoassay (ELISA) one of the most specific for the diagnosis of syphilis. Today, the indirect variant of ELISA is most often used. The advantages of this research method are obvious: not too much cost, ease of implementation, high accuracy of the result, with the help of this analysis it is possible to detect syphilis at an early stage, quick results.

At the core immunoblotting method lies enzyme immunoassay, which is combined with electrophoresis. It is one of the most specific tests and with its help, syphilis infection is confirmed.

polymerase chain reaction (specific research method) carried out to establish a diagnosis in the latent course of syphilis infection. When conducting PCR, the pathogen is found in the test material, even at the initial stage of the disease. The detected genetic material is divided by DNA and thus it becomes very easy to detect the pathogen. In neurosyphilis, when it is very difficult to detect an infection when conducting other tests due to very low sensitivity, in congenital syphilis, in the primary stage of seronegative syphilis, and for making a diagnosis in HIV-infected people, PCR is indispensable. Study cerebrospinal fluid with syphilis, it is carried out if there are clinical lesions of the nervous system at an early stage of the disease, with a latent form, and always before the start of treatment. Also, this analysis is prescribed for patients with neurosyphilis in the late stages of syphilis and with a latent form. The clinical laboratory conducts a study of cytosis, protein content, Pandey and Nonne-Apelt reactions. In serological laboratories, the Wasserman reaction, the Lange reaction, RIF, RIFyu, RIFts, RIT are carried out.

The site provides reference information for informational purposes only. Diagnosis and treatment of diseases should be carried out under the supervision of a specialist. All drugs have contraindications. Expert advice is required!

Contacting a venereologist - why is it necessary?

Anamnesis- collection of information necessary to identify the diagnosis: patient complaints, information about some aspects of sexual life and contacts with suspected sexually transmitted diseases persons. Past sexually transmitted diseases, information about the results of their treatment. All this information allows the attending physician to concentrate on the most likely diseases that caused the patient to seek specialized help.

Followed by clinical examination. The mucous membranes and skin of the genital organs, the anus area, and the oral mucosa are subjected to the most careful examination. Increased attention is paid to palpation of the outer groups of lymph nodes, palpation of identified infectious necrotic foci. Often at this stage, the diagnosis of syphilis can be made with a fairly high degree of probability.

However, in order to make a final diagnosis, as well as to monitor the dynamics of the process during the ongoing treatment, it is necessary to conduct laboratory tests.

Laboratory confirmation of syphilis - what does it include and how is it done?

2. Direct fluorescence reaction. This diagnostic method is preceded by the processing of the biomaterial with a special fluorescent serum, which leads to the attachment of specific immune complexes on the surface of pale treponema. As a result of this reaction, when microscopy of the processed biomaterial in a fluorescent microscope, pale treponema looks luminous and elegant.

3. PCR ( polymerase chain reaction). This method allows you to identify the DNA of an infectious agent, making its presence in the patient's body clear.

How are immunological signs of syphilis detected, and why should they be detected?
The whole group of studies of immunological parameters for the purpose of diagnosing infectious diseases is called serology. Nowadays, there are many serological diagnostic methods, but all of them are united by the fact that the biomaterial in diagnostics is the patient's blood. With regard to the diagnosis of syphilis, all serological tests can be divided into treponemal - detecting antibodies against the structural elements of pale treponema and non-treponemal - revealing immunological changes associated with the consequences of bacterial activity.

Non-treponemal serology
1. Precipitation microreaction (VDRL). This study detects in the patient's blood antibodies produced by the immune system against cells damaged by pale treponema. This test has high reliability, but low specificity. The fact is that detectable antibodies can be present in the blood in many diseases and pathological conditions. Therefore, this test is used only as a screening for a disease, revealing a suspicion of a disease. However, this method has an invaluable advantage in diagnosing the effectiveness of the treatment. If the patient is cured, the precipitation microreaction with the cardiolipin antigen becomes negative, unlike other serological types of research, which can give a positive result for a long time.

2. Wasserman reaction. This study is associated with the complement fixation reaction - one of the mechanisms for the implementation of the immunological response.
The test is evaluated in pluses ( not in crosses, as many believe!). And the reaction is negative as a result of the survey indicated minus), doubtful ( as a result of the survey, 1 plus + is indicated), weakly positive ( as a result of the examination, 2 pluses are indicated ++), positive reaction ( as a result of the examination, 3 pluses are indicated +++), a sharply positive reaction ( as a result of the examination, 4 pluses are indicated ++++).

Treponemal serology
1. Immunofluorescence reaction (RIF). This type of study detects antibodies produced by the immune system of an infected person. For this, the interaction of the patient's blood serum and a specific preparation containing antibodies is performed. After mixing the patient's blood plasma and the reagent with specific antibodies labeled with a special fluorescent substance, they are bound. The study is carried out using a special fluorescent microscope.

2. Enzyme immunoassay (ELISA). This analysis deserves more details. Since it is the main one in identifying most infectious diseases. The method is based on a selective highly specific antigen-antibody reaction. One of the features of this analysis is that it can be used to detect antibodies of various classes ( IgA IgM IgG ) . Also important is the ability of this analysis to determine the amount of antibodies detected. As a result, the determination of the type of antibodies and its quantitative component allows us to draw a number of conclusions about the duration of the disease, the dynamics of the process, the activity of the pathogen and the patient's immune system. As a result, this analysis turned out to be indispensable in diagnosing infectious diseases, as well as monitoring the dynamics of the disease against the background of ongoing treatment.

3. The reaction of passive hemagglutination (RPHA). This reaction is based on immunologically induced agglutination of erythrocytes. The mechanism of this reaction is that erythrocytes are preliminarily prepared, on the surface of which the protein components of pale treponema are fixed. Therefore, when mixed with blood plasma containing antibodies to treponema, erythrocytes stick together - the blood turns from red to granular. A positive hemagglutination reaction becomes 4 weeks after infection. After successful treatment of syphilis, this reaction can remain positive throughout life.

From the foregoing, it is clear that the matter of diagnosing, monitoring the effectiveness of treatment and cure is a rather complicated and time-consuming work. And it is impossible for a patient who does not have a medical education to understand the goals and results of the study. However, we will try to present in an accessible form the dynamics of immunological changes at different stages of syphilis, and laboratory indicators that reveal these changes.

So - a little theory. After infection, immune cells first encounter treponema pallidum. Identifying it as a foreign microorganism, immunocompetent cells begin the active formation of an immune response. Antibodies specific to treponema pallidum IgM, are found in the patient's blood 7 days after infection, antibodies IgG synthesized later - after 4 weeks. These 2 classes of antibodies are different in structure, but it is important for diagnosis that IgM synthesized in the early stages of infection ( What does it mean for a recent infection?) or in the presence of high infection activity. The detection of IgG only indicates the formation of stable immunity to this infection, only a series of analyzes of the antibody titer in dynamics allows us to assess the cure of the disease or the activity of the infection. Antilipid ( non-specific) immunological complexes are actively synthesized 4-5 weeks after infection.
Important is the fact that during the period of clinical manifestations of syphilis in the blood, antibodies specific for pale treponema are detected as IgM, and the class IgG (total antibodies). An important parameter in the treatment process is the change in the quantitative parameters of antibodies. Properly selected treatment contributes to a sharp decrease in concentration IgM, against the background of a stable level IgG- these indicators indicate the formed stable immunity to pale treponema against the background of a decrease in its infectious activity. It is necessary to pay attention to the fact that specific antibodies to treponema can remain in human blood for many years, giving positive results in some types of studies.

How to interpret the results of serological studies?

Reagin tests are used for mass screening of patients for syphilis. They are usually carried out as part of preventive examinations. Such tests are available in every medical facility and are carried out quickly. The answer is usually ready after 30-40 minutes.

A positive result during reagin reactions is not a criterion for making a diagnosis. Additional species-specific studies are needed.

The most common screening method is the Wasserman reaction. It uses cardiolipin and treponemal antigens. If there are no reagins in the blood serum, then hemolysis of ram erythrocytes will occur, which are added as an indicator.

In the presence of reagins, whole erythrocytes will precipitate, in which case the reaction is considered positive.

Reaginic in the following cases:

• other diseases, the causative agents of which are similar in antigenic structure to pallidum spirochete
• pregnancy
• oncological diseases
• taking salicylates
• myocardial infarction
• technical errors in the analysis

With a positive result of the reaginic reaction, specific serological tests are performed. They are also prescribed if a negative result is in doubt.

Treponemal antigens are used in such assays as RIF, RIT, ELISA, TPHA, hemadsorption reaction in the solid phase. These reactions are based on the formation of antigen-antibody complexes and differ in the method of their determination. The most commonly used reaction is immunofluorescence.

The drug is treated with luminescent serum, which allows you to determine the immune complexes under a fluorescent microscope.

One of the most sensitive serological tests for diagnosing syphilis is TPHA. The method has high accuracy. It is often used to verify the diagnosis during pregnancy when other tests may give a false positive result.

Features of serodiagnosis

For serological diagnosis of syphilis in its different periods draw blood from a vein. The analysis is recommended to be carried out on an empty stomach, this reduces the number of false positive results. The tube must be sterile. When conducting express tests, in some cases, blood is taken from a finger.

If suspected, cerebrospinal fluid is taken for serodiagnosis. For its analysis, the same methods are used as in the study of blood.

To diagnose syphilis, go through a complete examination in our clinic.