VDRL & RPR Syphilis Testing in Bengaluru
Quantitative non-treponemal titers paired with treponemal TPHA reflex confirmation. NABL Accredited laboratory testing with discrete doorstep collection.
Why Quantitative Titers Matter in Syphilis Diagnosis
In accordance with Koneman's Color Atlas and Textbook of Diagnostic Microbiology (7th Edition, Chapter 20: The Spirochetes) and the CDC STI treatment guidelines, evaluating syphilis requires understanding non-treponemal versus treponemal antibody dynamics:
1. Non-Treponemal Tests (RPR / VDRL)
Detect antibodies against cardiolipin-lecithin-cholesterol antigens. Because these levels correlate with active spirochete activity, quantitative titers (e.g. 1:2, 1:4, 1:8, 1:16, 1:32) are reported. Following effective penicillin therapy, these titers decrease by four-fold (e.g., from 1:16 to 1:4).
2. Treponemal Confirmation (TPHA / TPPA)
Detect specific antibodies against Treponema pallidum surface proteins. These tests confirm whether a positive RPR is a genuine syphilis infection or a biological false positive. Treponemal antibodies typically remain reactive for life even after complete clinical cure.
When Should You Get a Syphilis Test?
- Presence of a genital sore or chancre: Primary syphilis begins with a single, firm, round, typically painless ulcer at the site of infection (genitalia, rectum, mouth).
- Secondary rash: Non-itchy reddish-brown rash on the palms of the hands and soles of the feet, accompanied by swollen lymph nodes or fever.
- Known sexual partner exposure: Routine partner testing following a partner's positive diagnosis.
- Routine sexual wellness / pre-marital screen: Annual screening for sexually active adults.
Frequently Asked Questions About Syphilis Serology
What is the difference between a VDRL and an RPR test?
Both VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) are non-treponemal serological tests measuring antibodies against cardiolipin released by cellular damage during Treponema pallidum infection. RPR uses carbon particles to visualize agglutination macroscopically without a microscope, making it faster and standardized for serum, whereas VDRL can also be performed on cerebrospinal fluid (CSF).
What does an RPR titer (e.g. 1:16 or 1:4) mean?
The titer represents the highest serum dilution at which antibody reactivity is still visible. A higher titer (such as 1:32 or 1:64) generally indicates active or recent infection, whereas lower titers may indicate early infection, late latent syphilis, or treated past infection. Monitoring for a four-fold drop in titer (e.g., from 1:32 down to 1:8) is how physicians confirm treatment success.
Can a VDRL test give a false positive?
Yes. Non-treponemal tests are sensitive but not 100% specific. Biological false positives (BFPs) can occur in pregnancy, autoimmune disorders (like lupus), acute viral infections (Epstein-Barr, hepatitis), malaria, or following recent vaccinations. That is why CDC and Koneman diagnostic microbiology guidelines insist on confirming every reactive non-treponemal test with a specific treponemal assay like TPHA.