The search for syphilitic infection includes two fundamentally different specific laboratory methods: non-treponemal and treponemal. The first one is intended for mass use, since it does not require large expenditures and expensive equipment for the laboratory. It is the determination of antibodies to lipids (molecules of a fatty nature) that are part of the cell wall of bacteria and the membranes of their intracellular structures (mitochondria). This is the RPR method (rapid plasma reagin), better known as the micro-precipitation reaction (MRP). Despite the high specificity (about 100%), the sensitivity of the assay is slightly lower (80-90%), since such antibodies can be produced by the immune system in response to the introduction into the body of malaria plasmodia, pathogens of atypical pneumonia, mycobacterium leprosy, as well as in HIV infections. This suggests that the result of the RPR method is sometimes false positive.
To confirm or exclude the diagnosis, a more sensitive treponemal method (up to 100%) is used - a study of direct antibodies to the causative agent of syphilis. This is a secondary diagnosis of the disease, specifying the stage when the RPR is positive or questionable. This analysis involves the identification of immunoglobulins-AT, inherent exclusively to Treponema, using high-tech methods of polymerase chain reaction, passive hemagglutination reaction or immunofluorescence, therefore, its conclusion has an extremely low risk of error.
There are false positive responses in primary RPR diagnostics;
With lupus, autoimmune thyroiditis and other autoimmune processes;
Injecting drug addicts;
Weakened people.
Anti-Treponema Pallidum is used for exclusion and false negative RPR assays. In such a situation, the indication is:
A clear clinical picture, regardless of the period of the disease (chancre, secondary or tertiary syphilis);
Reliably known fact of contact with a charged person;
Infected parents.
Despite the presence of strict indications for the appointment of this examination, it is also performed at the request of the patient himself, who considers it necessary to finally exclude the circulation of treponema pale in his blood. The only thing is that a specialist consultation will allow you to choose the right time for the study and conduct a professional interpretation of the results.
