False syphilis, what is it? Erroneous test results for syphilis. False-positive and false-negative results False-positive test for syphilis

Testing may be treponemal or nontreponemal.

Non-treponemal tests include RPR - cardiolipin test, and. The cardiolipin test identifies antibodies to cardiolipin. Cardiolipin is a substance that is formed during many infectious and inflammatory processes.

There are more than 200 antigens that are similar in composition to the antigen of the causative agent of syphilis. Because of this, false positive test results for syphilis occur.

Important! The error of non-treponemal tests can be up to 20%.

Treponemal tests are specific and considered more accurate.

These analyzes are:

• ELISA– enzyme immunoassay
• PCR– polymerase chain reaction

PCR is considered the most accurate analysis, but can give false results negative result. The false-positive rate of treponemal tests for syphilis is very low. The reasons why they occur have not been precisely established. Most often, a false-positive result of such tests occurs with systemic lupus erythematosus and borreliosis.

False-positive syphilis during pregnancy

Often the cause of a false-positive reaction to syphilis is pregnancy.

According to studies, the error of non-treponemal tests in pregnant women is up to 1.5%. It is impossible to accurately determine the cause of false-positive reactions during pregnancy. Carrying a fetus leads to significant changes in a woman’s body. The mother's body produces large number various proteins. Nontreponema tests may recognize them as antibodies to Treponema pallidum.

If syphilis is confirmed, pregnant women are prescribed antibiotics.

The risk of developing congenital syphilis is significantly higher than the risk of such treatment.

Diagnosis of false-positive syphilis

If a positive test for syphilis is received, additional tests are required.

Positive reactions of non-treponemal tests are verified by treponemal studies. If the treponemal test gives a positive result, the test is repeated after 2-3 weeks.

If you test positive for syphilis, consult your doctor.

In our medical center you can get advice from an experienced venereologist.

2014-03-06 01:19:41

Maria asks:

Good afternoon

Answers Kovalenko Andrey Vitalievich:

Immunological tests may depend on the patient's status. Ribt and Reef remains a classic. The child should already be removed from the controls.

2014-03-06 00:59:58

Maria asks:

Good afternoon
During pregnancy (5 weeks), tests for syphilis (VDRL ++, TPHA +++) were positive. In the RIF-a dispensary, RIF-200 (positive) RIBT is negative, weakly positive. then positive), RV (negative), microreaction (positive) Diagnosis: late latent syphilis (I suspect that I had been ill for 9 years before pregnancy, without treatment, RV was normal then). Was treated with water-soluble penicillin (4 million units per day) - 30 days (18-22 weeks pregnant), prof. treatment with the same doses - 15 days (24-26 weeks). After treatment with RIF-a, RIF-200, RIBT - positive. Before birth, 2 control RVs are negative. After giving birth: my and the baby’s RV is negative, my micro reaction is positive. (1:2), in a child - positive. (no caption). The child was born full-term, there were minor neurological problems (sitting, walking on time). The ophthalmologist had no comments; the cardiologist found chordal murmurs. In 2010, the results of all my tests were again positive (RIBT, RIF-a, RIF-200, enzyme immunoassay with trepon antigen, VDRL positive 1:2, anti-Lewis IgG antibodies - positive). We recommend plasmaphoresis or antibiotic therapy with three different drugs(did not pass because the child was on breastfeeding). In 2011, 2 VDRL tests were negative, anti-Lewis antibodies (IgG) were positive. In 2012, tests were done on the child: VDRL – negative, anti-Lewis antibodies (IgG) – negative. In 2014, I took tests for control, VDRL was positive 1:2, antibodies to Lewis (IgG) were positive 9.92. I know that treponemal tests can remain positive for a lifetime; the dispensary does a full package of tests without focusing on this (I monitor it in a private laboratory). My questions: 1. Why did VDRL become positive? 2. Is a false positive result possible against the background of exacerbation of chronic diseases? gastrointestinal tract or weakened immune system? 3. What extras? tests need to be taken and is it necessary at the moment with existing exacerbations (RPR or other non-treponemal tests)? 4. Is it necessary to re-examine a child with negative tests in 2012 (child is 6 years old) Thank you in advance and hope for an answer.

Answers Kovalenko Andrey Vitalievich:

Good afternoon, there is no need for additional examination and treatment. The child underwent a complete medical examination. VDRL fluctuations are possible.

2012-03-13 10:53:41

Nina asks:

Hello! in March, at the 37th week of pregnancy, a test for syphilis showed a positive result “sum MG sex” (as written in the referral for re-test). Previous tests in October and February were negative. During previous pregnancies (this is the third), the tests were also negative. She herself was not sick, at present there are no signs of the disease, but her husband was treated 15 years ago, took tests in September, and the result was “ELISA total antibodies to syphilis are positive.” They said that this is possible even with the treatment. The question is: “Are such results possible for me, because of his long-standing illness, then why were the previous results negative? How can this affect the child, since the pregnancy is long? Or is it an infection? happened recently, I had no outside connections and he says that he did too. Today I took a second detailed test at the Speed ​​Center, the result was only after 4 days, you can go crazy, or it was a false positive result.

Answers Kravchuk Inna Ivanovna:

Dear Nina. If the diagnosis of syphilis was made before pregnancy and full treatment was carried out, then the risk of transmitting the infection to the child is less, the more time passes after treatment before pregnancy. If in the past the father of the child also had syphilis, full treatment was carried out, but at the moment there are still positive non-treponemal tests, and more than a year has passed since the end of treatment, then this situation poses a danger primarily to the health of the man who may , required additional treatment. It is not dangerous for a pregnant woman and child. In our opinion, we can talk about a state of seroresistance after treated syphilis or a false-positive test result.

2010-11-12 09:47:22

Ilya asks:

Hello. I am 25 years old. I took a test for HIV (antigen + antibodies) 3 months after the possible infection - negative, but I also took a test for syphilis. The test for syphilis turned out to be positive, the doctors said that my test was most likely false positive, because I had not been diagnosed with syphilis before and I was also given prophylaxis against syphilis after dangerous situation. And most importantly, two weeks ago I was bitten by a dog and now I am getting a rabies vaccine, the doctors say that this could have influenced the incorrect result, and they also say that the results of HIV tests may also be incorrect... Please tell me, maybe -Can a negative HIV result be false due to the rabies vaccine, and if so, how long can I wait for the HIV test result to be as reliable as possible? Thank you.

Answers Silko Yaroslav Gennadievich:

If you took an HIV test using the immunoblot method (antigen + antibody) in a certified laboratory, then this is the most reliable result, and the rabies vaccine is unlikely to affect the result of the HIV test - this is a highly specific test. Take the HIV test using the standard ELISA method after 3 months for control.

2010-04-17 11:42:42

Elena asks:

Hello! I’m 4-5 weeks pregnant. I was tested for all STIs in a paid clinic, and there was a positive test for syphilis (total AT to Treponema bl. 1.3, and Rmp, but Rmp was negative), I was referred to a venereologist. There I donated blood , but the results will only be on Wednesday. I’m very worried.. I only had one male partner. I’m sure of him. Could this be a false positive result during pregnancy?

Answers Consultant at the medical laboratory "Sinevo Ukraine":

Good afternoon, Elena! Yes, indeed, there may well be a false positive result. This occurs quite often during pregnancy. Additional research will help determine whether everything is completely in order with your health. But you have no reason to panic. Therefore, stop worrying, wait for the test results, and then go back to the face-to-face appointment to a venereologist. The doctor will explain everything to you in detail and issue a report for the antenatal consultation (so that they leave you alone). Good luck to you!

2014-09-25 20:33:05

Elena asks:

Hello. I donated blood from a vein in the gynecology department. They sent a letter to appear at the KVD. They said I had syphilis. I didn’t see any tests; they didn’t want to conduct additional research to confirm it. She barely insisted on donating blood again. I couldn’t come there anymore, I had work. But I passed it at INVITRO. RPR - positive and reminder (IN CAPTION 1:8
False-positive reactions are possible, incl.
for some diseases, during pregnancy.
Screening positive for RPR
should be supplemented with a treponemal test (Method.
instructions of the Ministry of Health of the Russian Federation to Pr. No. 87 03/26/2001) - see No. 70
anti-Tr.pallidum IgG+IgM). The young man's RPR is negative. How is that??? I’m not pregnant, I haven’t had it, I’ve never cheated on him. together 4.5 years. And if I have it, why didn't my boyfriend get it?

Answers Gudarenko Vera Yurievna:

Hello Elena! Having familiarized myself with your situation, I can give strong advice!!! Don't put this situation off for too long!!! Work is not a wolf that will run away into the forest. Resolving this situation is a top priority! You urgently need to undergo a re-examination, if desired, and contact a dermatovenerological clinic!!!

2009-07-16 12:05:16

Dima asks:

I recently did an express test for HIV (two stripes appeared, the first one is very dim, but it’s still a stripe). The doctor recommended that I also get tested at Otdyha or Trekhsvyatitelskaya. I was almost resigned to the thought that I had it, but then I read that this test can show a false positive result if the person was or is sick. “ELISA can give false positive results. False positive results can be obtained when examining patients with chronic infectious, autoimmune, oncological diseases and in some other cases." I just had one Autoimmune disease... with the skin... I don’t remember accurate diagnosis... something like "...buloses" - such swellings on the skin with water as with syphilis (then I was tested for sif, it was negative)
Hope dies last, tell me how realistic a false positive result can be in general. Because the doctor said that the test is extremely accurate.

Answers Medical consultant of the website portal:

Hello, Dima! Judging by your letter, the test you took is a rapid test based on the immunochromatography (ICA) method. The accuracy of this method is 99.5%. In addition to the reasons you listed for false-positive results, manufacturers indicate the following reasons for erroneous results: liver disease, vaccination (vaccination, for example, against influenza), violation of storage conditions and testing procedures. Therefore, the positive result obtained during rapid testing is preliminary. The diagnosis of HIV infection is not made until the result of rapid testing is confirmed by repeated blood testing using other methods - ELISA (enzyme-linked immunosorbent assay) or immunoblotting. Be sure to get re-examined. It is best to do this at the regional AIDS center. Be healthy!

2007-10-17 15:39:54

Tatiana asks:

Dear Igor Semenovich! I am very concerned about this question: I am at 20 weeks. pregnancy, while being kept in the clinic, a blood test showed syphilis (+++). An examination at the dermatovenous dispensary showed the same result (three pluses). I do not have any signs of this disease and have never had it before. A blood test was taken from the husband for RV - nothing was detected. My husband and I have been having regular sex life for a year now. One doctor immediately said that this was false-positive syphilis during pregnancy and that this sometimes happens, but another categorically prescribed treatment with injections of penicillin antibiotics for 2 months. I am in shock, I am very worried about the unborn baby. Please help me make the right decision. Thank you in advance.

Content

Syphilis is common venereal disease, if it is not detected in time, the body will suffer serious damage and possible death. The Wasserman reaction is a special analysis that should be done if this pathology is suspected; timely diagnosis will help to immediately cure the disease if the result is positive. You can become infected with syphilis not only through sexual contact, but also through household items, hygiene products, and bedding.

Methods for diagnosing syphilis

Tests must identify the main causative agent of the disease - treponema pallidum aka Treponema pallidum. To do this, blood is drawn on an empty stomach for serological analysis. Such research is considered to be the main type laboratory diagnostics to detect syphilis. The most common research methods are:

• blood test for RW (RW) - Wasserman analysis;
• RPHA – passive hemagglutination reaction;
• ELISA – enzyme immunoassay of blood;
• RIF – immunofluorescence reaction;
• RPR – microprecipitation reaction with cardiolipin antigen;
• RIBT – immobilization reaction of Treponema pallidum.

What is the Wasserman reaction

This laboratory analysis blood for syphilis, which is aimed at determining the immunological reaction to the penetration of the pathogen into the body. Characteristic processes begin in the human body during infection. The causative agent of the disease contains the antigen cardiolipin. The patient's blood serum, due to the presence of reagins in it, enters into a complement fixation reaction. The result is a specific complex with this antigen, which RV can detect.

When infected with syphilis, a person will definitely have antibodies to Treponema pallidum in their blood, which is characterized as a physiological response immune system. During the test, the drug cardiolipin is added to the collected blood. If the causative agent of syphilis is already in the body, the result will be visible RSC, which binds the introduced antigen and antibodies. In the decoding, the number of “+” signs indicates the intensity of the formation of complexes or “-” in their absence.

Indications for the study

It is recommended to carry out regularly general analysis blood in order to promptly identify any abnormalities in the human body, early stage staging the reaction can significantly increase the effectiveness of treatment. The following indications exist for donating serum to RW:

1. During professional examinations and medical examinations on a regular basis for employees of trade, medicine, and education.
2. During pregnancy. There is a possibility of infection of the fetus with syphilis in the womb, so it is important to identify the result of the Wasserman test in women who are planning to give birth to a child or are already carrying one. Pathology can cause serious harm to the baby.
3. People who have had long-term contact with pathology at work or at home.
4. If a person suffers from alcoholism or drug addiction.
5. During urgent hospitalization of a patient with signs of syphilis.
6. After intimacy without using a contraceptive with a random person.
7. Anyone wishing to become a blood or sperm donor must be tested.
8. If the pregnancy was terminated unnaturally.
9. The test is carried out during and after serving time in prison.
10. The reason for performing RV is the hospitalization of a patient with enlarged nodes lymphatic system and elevated temperature.

Blood for the Wasserman reaction during pregnancy

This is the initial test that your OB/GYN will ask you to take. A blood test for the Wasserman reaction may be inaccurate because the woman’s condition during this period affects the results. According to statistics, 32% of cases show a false positive result. If there is a “+” in the decryption, you must go through differential diagnosis. It is recommended to perform the test once per trimester, regardless of the presence or absence of sexual intercourse. There are no contraindications for RW for pregnant women; this is a standard collection of material.

Preparation

Some tests require specific preparation before taking. Wasserman's analysis will be as reliable as possible if 2 days before the test you do not drink any alcoholic beverages (even low-alcohol ones). It is recommended not to eat fatty foods during this period, so as not to distort the results. You should not take any digitalis preparations while preparing for RV.

How is the procedure performed?

Blood for the Wasserman reaction is carried out only on an empty stomach, this is an important condition. The last meal before collection should be no later than 6 hours. The employee who performs the manipulations sits the client on a chair or places him on a couch. The analysis requires 8-10 ml of blood from the cubital vein. If the study is carried out small child, then the material can be taken from the jugular or cranial vein.

How many days does a blood test for RW take?

There are two stages in conducting material research. Wasserman's rapid test will be ready in 2 hours, but it can only confirm or refute the presence of syphilis antibodies in the patient. To obtain quantitative information on the state of the blood and the concentration of antibodies to treponema, it takes from 1 to 7 days. The duration of analysis and interpretation depends on the laboratory and the number of ongoing tests.

Decoding

A blood test according to Wasserman should only be deciphered by a qualified doctor. The results may indicate not only a negative or positive reaction, but also something in between. Only a specialist will be able to correctly interpret the data and not frighten the patient ahead of time. A typical negative result is indicated by a “-” sign and indicates the undoubted absence of syphilis in the human body.

Positive reaction

When assessing the concentration of antibodies, a positive manifestation may be marked by one, two, three or four pluses. The following symbols may appear in the decoding:

1. “+” and “++” - the result indicates a dubious, weakly positive microreaction. Additional diagnostic tests and examination. After some time, you can repeat the analysis of August Wasserman, because there is no complete confidence in the absence or presence of syphilis. The reason for this result may be a violation preparatory procedures before donating blood.
2. “+++” is a positive reaction. No additional or repeated confirmation is required; the patient has syphilis and should undergo full examination. Women are prescribed a smear from the vagina or uterus, men donate material from the urethra. This result is rarely erroneous, but clarifying tests may be prescribed if the patient’s symptoms are similar to other diseases.
3. “++++” is the final positive result. High reaction intensity.
4. “++++” is the final positive reaction. The result obtained is 100% reliable and does not require any additional tests. The diagnosis is syphilis.

False-positive Wasserman reaction

This answer can be absolutely healthy person, this happens for specific reasons. This reaction occurs if the patient has acute or chronic stages of the disease, has recently received vaccinations, or has recently suffered physical injury. All these conditions lead to the active production of a nonspecific protein in the body, which is called antibodies or immunoglobulin. The RW analysis is aimed at identifying these proteins and recognizing them as syphilitic. This becomes the basis for obtaining a false positive result.

Reasons

It was described above why a patient may receive a false positive result when testing for syphilis. Here is a list of conditions that can lead to this:

• myocardial infarction;
• alcoholic, food poisoning;
• acute, chronic liver pathologies, hepatitis D, C, B;
• soft tissue or bone injuries;
• age-related changes in the functioning of the patient’s body;
• tuberculosis;
• autoimmune diseases.

Video

Attention! The information presented in the article is for informational purposes only. The materials in the article do not encourage self-treatment. Only a qualified doctor can make a diagnosis and make treatment recommendations based on individual characteristics specific patient.

Discuss

How to take a blood test for the Wasserman reaction - test indications, preparation and interpretation of results

False-positive syphilis is a common problem that anyone can encounter. Moreover, we get tested for this disease quite often. When determining for inpatient treatment, before leaving for a sanatorium, when applying for a job. It’s natural that people get scared when they see positive results. They think that they have a serious disease that is dangerous to others.

In what cases is it possible to diagnose false-positive syphilis, patients ask their doctors, and which tests can be trusted.

Who should be notified of the results, and what should I do if they are positive in a pregnant woman?

Syphilis: types of tests for Treponema pallidum

Before you figure out why it was received false positive reaction for syphilis, it is necessary to understand what tests are used today to diagnose this disease.

Syphilis is a pathology caused by a bacterium called Treponema pallidum. It is transmitted mainly through sexual contact. But when it enters the body, it has the ability to affect not only the genitals, but also the body as a whole. In the advanced stages of the disease, the nervous, cardiovascular, digestive and other systems suffer from it, and the person often does not survive. Earlier diagnosis illness was unreliable.

However, today doctors are making efforts to introduce new methods into use that make it possible to make a diagnosis with a minimal probability of error.

There is a whole group of different tests that help them in this difficult task.

Non-treponemal techniques

Research by this group is not aimed at identifying the pathogen itself, but at searching for its traces. This is done by identifying special proteins produced either by the body or directly by the bacterium. The methods of this group have a high probability of error, but they allow us to understand how severe the infection is.

• Precipitation microreaction. Based on reactions that occur between antigens and antibodies. It has controversial specificity, which is why it is also used as a screening method and not as a confirmation method. Has several analogues.
• Wasserman reaction, also known as RW. The technique is widespread due to the fact that it is inexpensive and quick to perform. Both venous and arterial blood, and also cerebrospinal fluid. Belongs to a group of screening tests popular in all laboratories.

Treponemal tests

Analyzes from this group are highly accurate.

The likelihood of getting a false positive result for syphilis when using these methods is minimal.

The methods are quite expensive. They are not recommended for screening, but they are excellent for confirming or denying a diagnosis.

High accuracy diagnostic methods

The methods of this group are characterized by high reliability and minimal risk of obtaining incorrect results. However, they are also known for their high cost due to the need to use specific equipment.

• PCR. A method based on searching for the microorganism itself, or rather its DNA particles in the human body. Requires the use of special equipment and reagents.
• Immunoblotting. A combined technique based on a combination of electrophoresis and ELISA. Thanks to electrophoresis processing of blood elements, it is possible to significantly increase the reliability of ELISA testing.
• RIBT. An analysis that is highly specific. The likelihood of a positive result if the patient is completely healthy is minimized. Used to diagnose complex forms of syphilis that occur with damage to the nervous system.

False-positive syphilis: why and when changes occur

A person may receive false-positive results from standard free tests for a number of conditions not associated with Treponema pallidum infection. For example, this is possible with a cold, with autoimmune diseases, injuries of various locations, etc. All these conditions are united by the fact that during them the body begins to intensively produce antibodies designed to fight the antigens of the pathogenic microorganism. Moreover, some antibodies resemble in structure those produced during infection with Treponema pallidum. This gives rise to the possibility of false positive results.

Doctors call a number acute conditions, which can provoke a long-term increase in antibody titer. These include:

• ARVI and other similar ailments that occur with an increase in body temperature;
• myocardial infarction;
• injuries;
• period after vaccination;
• acute poisoning.

Separately, there are also a number of conditions in which the test for syphilis can be chronically positive. Such conditions include autoimmune diseases, liver pathologies, age-related deformations of the body, HIV infection and viral hepatitis etc.

What tests for syphilis can you trust?

False-positive syphilis is quite rare due to its high specificity modern research. However, the possibility of obtaining incorrect results still exists.

The accuracy of the analyzes largely depends on how the biological material was collected and how it was stored immediately before the start of the study. The accuracy of the equipment and the reagents used for various reactions are also of considerable importance.

It is also important whether Treponema pallidum itself or its analogues are taken for research. In the first case, it is possible to obtain more accurate results. Since the likelihood of a reaction with similar antibodies is minimized.

However, non-treponema tests are the most commonly used. This is explained by their low cost compared to the treponemal research option.

Treponemal test options may give incorrect results with a 1% chance. Non-treponemal methods give an error with a probability of up to 10%. The difference is noticeable.

How to tell if a syphilis test result is wrong

Patients mistakenly believe that if the results indicate “positive” or “negative”, then everything is clear with the results. However, any doctor will tell you that even clear results should be treated with suspicion. If, for example, there is a discrepancy clinical picture results.

The inscription in the results column “dubious result” completely puts people far from medicine into a stupor. The first thought in this case is research error.

A questionable result does not always indicate a test error. Sometimes, as doctors note, it is possible after suffering from syphilis. Or if the disease has just begun to develop and has not yet had time to provoke a full-fledged reaction from the body’s immune system.

If a non-treponemal study shows questionable or strongly positive results, the patient is required to undergo an additional treponemal test. Based on it, full conclusions are already being drawn about whether infection has occurred.

A negative result indicates health, and a positive result indicates the need for therapy. In any case, it is recommended to retake questionable tests. The average interval between tests should be at least 14 days.

False-positive syphilis: the importance of spreading awareness

Patients are often interested in the question of where to go if a syphilidologist has determined that it is not syphilis, but the reaction is positive.

First of all, you should notify your sexual partner about the results. He is recommended to undergo testing for purely preventive purposes.

The patient is referred from the syphilidologist to other specialists. Among them:

• a therapist if there are signs of an obvious infectious process such as ARVI;
• infectious disease specialist if more serious cases are suspected infectious diseases, for example, for leprosy, HIV, viral hepatitis;
• immunologist for suspected problems with immunity, its decrease due to reasons of any kind;
• rheumatologist if there is a suspicion of connective tissue disease, etc.

It is important to remember that even a positive result with subsequent confirmation of the diagnosis is not grounds for dismissal from work. After all, treated syphilis does not pose a danger to others. And if you take care of the disease in time, then complete recovery occurs.

Doctors draw the attention of adolescents to the fact that they can also undergo examinations and tests at the medical checkpoint at their place of residence. Moreover, information about their illness will not be disclosed even to their parents if the diagnosis is confirmed.

Is it possible to have a false test for syphilis in pregnant women?

False-positive syphilis during pregnancy is a situation that any woman carrying a baby in her womb may encounter. Whether you should worry about your health and the health of your baby is up to the doctor to decide. Any representative of the fair sex during pregnancy must undergo testing at least three times. The first time it is performed is at 12 weeks. Then it repeats several weeks before childbirth and, finally, immediately before the birth itself. Naturally, receiving positive results from the Wasserman reaction, used in this case, the woman worries about where she got the disease. If after pregnancy or generally in the last six months there has been no change in sexual partners and there is complete confidence in his health, then the fears are in vain. The analysis is highly likely to be false. The fact is that pregnancy is a process accompanied not only by powerful changes in the hormonal sphere, but also by a pronounced restructuring of the immune system.

The immune system must prepare for the presence of an essentially foreign organism in the body for an extended amount of time. Naturally, at this time many antibodies are produced, some of which are similar in structure to antibodies to syphilis. They give a positive reaction when tested.

Preparing for a test for syphilis to avoid incorrect results

What set of tests to take if false-positive syphilis is suspected, patients ask their doctors. As already mentioned, treponemal tests are recommended. They allow you to make a correct diagnosis with 99.9% accuracy.

A little preparation is recommended before the tests. Firstly, you should stop drinking alcohol, fatty and fried foods at least 24 hours before testing. Secondly, you should come to the clinic or hospital to donate blood in the morning, on an empty stomach. Before the study, a short rest is recommended so that the body does not experience stress.

Diagnosing syphilis still presents some difficulties due to the possibility of obtaining false test results. Naturally, patients need to know in what cases tests can give incorrect results and how to double-check.

After all, ignoring the disease, as well as treating an absent pathology, can lead to serious complications!

If you suspect false-positive syphilis, contact the author of this article, a venereologist in Moscow with many years of experience.

False-positive serological reactions for syphilis (FPR)- these are positive reactions in people who have never been sick and do not have syphilis at the time of examination. That is, there is no specific infection in the body and there never was, and serological reactions give a positive result.

False-positive or nonspecific results are positive results of serological reactions to syphilis in persons who do not suffer from syphilitic infection, and have not had syphilis in the past.

Erroneous test for syphilis due to technical reasons

Decisional errors may be due to technical errors and errors during research, as well as the quality of reagents. Despite the numerous advantages of diagnostic tools for RPGA, ELISA and RIF and their modifications used for the diagnosis of syphilis, in some cases unreliable test results are noted. This may be due to both an insufficient level of qualifications and professional responsibility of personnel (the so-called non-biological or technical errors), and to the characteristics of the tested samples (biological errors).

Non-biological errors can occur at any stage of research: pre-analytical, analytical, and post-analytical, i.e. when collecting, transporting, storing biomaterial, using chylous, sprouted serum, during repeated freezing and thawing of test samples, as well as when using diagnosticums with expired suitability, etc. In particular, non-compliance with the storage conditions and periods of diagnostic kits causes a decrease in the sensitivity of the reaction and the receipt of false negative results.

False-positive results can be caused by contamination of the sera of patients seronegative for Treponema pallidum with traces of sera from seropositive individuals, which may occur during the preparation of the sera.

There are many other technical errors that lead to unreliable (false negative and false positive) and questionable research results. Some laboratories do not carry out internal and external quality control of syphilis tests, which leads to diagnostic errors and uncertainty among laboratory doctors in the results of the analysis.

The source of errors when performing nonspecific tests can be the non-use of control sera, uneven concentration of the antigen in the experiment due to insufficient mixing before use, contamination of samples and glassware with microorganisms, violation of the terms and conditions of storage of reaction components, violation of blood collection techniques.

In modern test systems, recombinant or synthetic peptides have been used as antigens. The former became more widespread. But with poor purification, Escherichia coli proteins get into the mixture of T. pallidum antigens, which leads to false serodiagnosis of syphilis in patients with escherichiosis or in healthy people whose serum contains antibodies to E. coli.

To a certain extent diagnostic errors Incorrect interpretation of the research results should also be included.

Acute and chronic DM

In addition to technical errors when performing tests, decision-makers can also be caused by the characteristics of the body. Conventionally, decision makers are divided into spicy (<6 месяцев) и chronic(stored for more than 6 months).

Acute DM can be observed during pregnancy and during menstruation, after vaccination, after a recent myocardial infarction, and in many infectious diseases. Infections in which PPR may occur are pneumococcal pneumonia, scarlet fever, infective endocarditis, tuberculosis, leprosy, lymphogranuloma venereum, chancroid (chancroid), leptospirosis and other spirochetoses, HIV infection, infectious mononucleosis, malaria, chicken pox, viral hepatitis, mumps , measles, respiratory diseases, influenza and dermatoses.

Acute PDs are unstable, their spontaneous negativity occurs within 4-6 months.

Chronic DM possible with autoimmune diseases, systemic connective tissue diseases, cancer, chronic pathology of the liver and biliary tract, cardiovascular and endocrine pathologies, blood diseases, chronic lung diseases, injection drug use, etc. In most of these conditions, anticardiolipin antibodies of the IgG and IgM classes ("reagins").

Chronic false-positive reactions can remain positive throughout life.

Chronic false-positive reactions may be preclinical manifestations of serious diseases. In case of malignant neoplasms and diffuse connective tissue diseases, the LPR titer can be very high.

Among the causes of chronic positive reactions are physiological conditions (old age). With age, the number of PD increases; in women they are observed 4.5 times more often than in men. In the age group of 80-year-olds, the prevalence of PD is 10%.

The cause of DPR may be the frequent use of intravenously administered drugs, frequent transfusions and infusions.

Chronic infections (tuberculosis, leprosy, infective endocarditis, malaria), myeloma can also cause PD.

Infection with other spirochete species

False-positive reactions of treponemal and non-treponemal tests can be observed in infectious diseases whose pathogens are antigenically similar to Treponema pallidum. These are relapsing fever, leptospirosis, tick-borne borreliosis, tropical treponematoses (yaws, bejel, pinta), as well as inflammatory processes caused by saprophytic treponemas of the oral cavity and genitals.

The causative agents of endemic treponematoses (yaws, pinta, bejel) are treponemas that have genus-specific antigens similar to those of T. pallidum. In this regard, antibodies formed to them are capable of cross-interacting with the antigen of the causative agent of syphilis.

Russia is not a territory endemic for this group of diseases. These infections occur mainly in Africa, Latin America and South Asia, and cases of the disease are rare in the practice of medical institutions.

A patient with positive serological reactions for syphilis who arrived from a country with endemic treponematoses should be examined for syphilis and prescribed anti-syphilitic treatment if it has not previously been administered.

Biological false-positive Wasserman reaction

Beginning in 1938, and especially during World War II, serological screening tests for syphilis became widespread in the United States. The researchers compared the data obtained and found that a positive or questionable reaction was found in people who did not have clinical and epidemiological signs of syphilitic infection or contacts with syphilis. Moreover, such results occurred much more often than previously thought. Positive results of nontreponemal tests with lipid or cardiolipin antigens (VDRL, in Kolmer tests, Kahn reactions) have been found in patients with various diseases, but without signs of syphilitic infection. Biological false-positive results have been identified in patients with autoimmune, inflammatory and hematological diseases.

In Russian-language medical literature, this phenomenon is called “ biological false-positive Wasserman reaction"(B-LPRV), because These results were observed during the most common test of those times - the Wasserman reaction.

It turned out that B-LPRV can occur in two main forms - acute and chronic. In the first case, in patients who have had an infection other than a syphilitic infection, B-LPRV disappears during the recovery process, and the duration of its detection does not exceed six months. In the second case, B-LPRV may persist persistently for many years in the absence of an obvious causative factor. In the early 50s, it was found that chronic B-LPRV is most often detected in autoimmune diseases, especially SLE, in which the frequency of its detection reaches 30-44%

False-positive nontreponemal (cardiolipin) tests

Lipid antigens of T. pallidum make up a significant part of the cell, but the body may also contain lipids with the same structure - autoantigens formed as a result of the destruction of organs and tissues (mainly lipids of mitochondrial membranes).

Syphilitic infection is accompanied by the formation of immune complexes and an autoimmune response to cardiolipin, fibronectin, collagen and muscle creatine kinase. In non-treponemal tests, a solution of three highly purified lipids (cardiolipin stabilized with lecithin and cholesterol) in ethyl alcohol is used as an antigen. Cardiolipin is not a specific component for T. pallidum and is also described as one of the phospholipids of human biomembranes. Therefore, antibodies to this antigen are recorded in serum during almost any alteration of human cells as a result of infections and under some physiological and pathological conditions.

Because the antigen used in non-treponemal reactions is found in other tissues, tests may give positive results in individuals without treponemal infection (1-2% in the general population).

The most common cause of biological false-positive non-treponemal tests is antiphospholipid syndrome, an autoimmune process that occurs in connective tissue diseases (systemic lupus erythematosus, dermatomyositis, scleroderma).

When using non-treponemal tests (RMT and its modifications), false-positive results may be due to the presence in the blood of antibodies to rheumatoid factor, cross-reacting antibodies in autoimmune pathology (“cress reactors”).

Other factors for the occurrence of false-positive results are considered to be some chronic bacterial infections (leprosy, etc.), diseases of viral etiology (infectious mononucleosis), and systemic connective tissue diseases.

Reasons may also include old age (over 70 years), pregnancy, extensive somatic pathology, lipid metabolism disorders, immunodeficiency states of various etiologies, systemic chronic diseases of the heart and lungs.

Other causes include cancer, tuberculosis, enteroviral infections, viral hepatitis, Lyme disease, pneumonia, alcoholism, drug addiction, diabetes, vaccination, other infections (malaria, chickenpox, measles, endo- and myocarditis), gout.

In these conditions, the development of immunological disorders is observed, leading to abnormal production of antibodies that can cross-react with treponemal antigens.

Table. Biological causes of false-positive reactions in nontreponemal serological tests.

False-positive treponemal tests

Compounding the problem, treponemal tests can also be false positive. The causes may be autoimmune diseases, collagenosis, Lyme disease, pregnancy, leprosy, herpes, malaria, infectious mononucleosis, tumors, drug addiction. In recent years, immunoblotting, one of the most modern methods for diagnosing syphilis, has begun to be actively used abroad to differentiate DM.

Antibody persistence after successful treatment

Specific diagnostic reactions remain positive for a long time even after full therapy. After effective treatment of a syphilitic infection, in most patients, titers in non-treponemal tests decrease by 4 times 6–12 months after treatment. However, with late initiation of therapy, titers even in non-treponemal tests may remain at the same level, but never increase.

False negative test results

Different diagnostic methods demonstrate different sensitivity and specificity depending on the form and stage of syphilis. The likelihood of an erroneous diagnosis increases, especially in cases of latent, hidden, combined course of the disease.

False-negative serological reactions for syphilis can be observed in secondary syphilis due to the prozone phenomenon when testing undiluted serum, as well as when examining immunocompromised individuals, such as HIV-infected patients.

False-negative results of serological specific tests (SSR) caused by biological factors may be due to competition between specific IgM and IgG for binding to the antigen on the surface of erythrocytes, as well as the “prozone phenomenon”. In the latter case, agglutination does not occur due to overproduction of antibodies to Treponema pallidum, since each antigen receptor on erythrocytes, due to excess antibodies, is associated with one agglutinin molecule, which prevents the formation of a “lattice.” Replacing RPGA with TPPA, i.e. erythrocytes on synthetic particles, apparently, will eliminate or minimize the receipt of false negative results.

In ELISA, such reactions can be explained by the presence of a seronegative phase in primary syphilis, and in secondary syphilis - by immune deficiency and the presence of HIV infection. When receiving a negative result from serological tests for syphilis, one should take into account the ability of Treponema pallidum to penetrate and multiply in various organs and tissues - searching for the pathogen in the lymph (lymph nodes) in some cases leads to a reliable result. It is also advisable to repeat the analysis of samples that gave a positive result. Repeated examination of sera after 5–7 or more days, as a rule, allows one to obtain reliable results.