What is the expected syphilis titre (Venereal Disease Research Laboratory test) after treatment for syphilis?

From the Guidelines

After successful treatment for syphilis, a four-fold decrease in Venereal Disease Research Laboratory (VDRL) test titer within 6-12 months indicates successful treatment, with primary and secondary syphilis typically showing this decline within 6 months, and late-stage syphilis taking 12-24 months. The expected outcome after treatment is a significant reduction in VDRL titers, which serves as a primary indicator of treatment efficacy since direct testing for cure is not possible in syphilis. Key points to consider in the management and follow-up of syphilis treatment include:

• Monitoring of nontreponemal serologic tests (such as VDRL) at regular intervals (e.g., 6,12, and 24 months) to ensure an adequate response to treatment 1.
• A four-fold decrease in titer is considered indicative of successful treatment, although the timeframe for this decrease can vary depending on the stage of syphilis at the time of treatment.
• For patients with HIV, more frequent monitoring may be necessary due to potential differences in treatment response and the higher risk of complications such as neurosyphilis 1.
• The development of "serofast" status, where titers decline but do not completely revert to negative, does not necessarily indicate treatment failure but requires careful clinical correlation and potentially additional follow-up or consultation with a specialist 1.
• Failure of titers to decline appropriately or a significant increase in titers suggests treatment failure or reinfection, necessitating further evaluation and potential retreatment, with consideration for CNS infection and the need for CSF examination in some cases 1.

From the Research

Expected Syphilis Titre after Treatment

The expected syphilis titre after treatment for syphilis can be summarized as follows:

• A decrease in Venereal Disease Research Laboratory (VDRL) titre is expected after treatment, with a good serological response defined as a ≥4-fold decline in VDRL titre within 12 months after treatment 2.
• The VDRL titre should decline fourfold within six months after treatment of primary or secondary syphilis and within 12 to 24 months after treatment of latent or late syphilis 3.
• Some key factors associated with serological failure after early syphilis treatment include:
  • Baseline RPR titer ≤1:16 4
  • A previous history of syphilis 4
  • A CD4 T-cell count below 350 cells/ml 4
• Different treatment regimens, such as single dose vs. three doses of benzathine penicillin G, have been compared, and the results support the current international treatment guidelines, recommending early syphilis treatment with a single dose of BPG in HIV patients 2.

Treatment Response

The treatment response can vary depending on the stage of syphilis and the treatment regimen used. For example:

• Doxycycline has been shown to be an effective alternative treatment for syphilis, with serological response rates of 100.0% in patients with primary syphilis, 96.9% in patients with secondary syphilis, 91.3% in patients with early latent syphilis, and 79.2% in patients with late latent syphilis 5.
• Ceftriaxone has been compared to penicillin G in the treatment of primary and secondary syphilis, and the results showed no detectable difference in clinical and serological response to syphilis treatment between the two treatments 6.