From the Guidelines
For a patient with an increase in Rapid Plasma Reagin (RPR) titer from 1:1 to 1:2, no treatment is recommended based on this single change, as it does not represent a fourfold increase in titer, which is the threshold for considering treatment failure or reinfection 1. The increase in RPR titer from 1:1 to 1:2 is not considered clinically significant, as a fourfold increase in titer is typically required to indicate active infection or treatment failure.
- The Centers for Disease Control and Prevention (CDC) guidelines state that a sustained fourfold increase in nontreponemal test titer is necessary to consider treatment failure or reinfection 1.
- A recent clinical trial demonstrated that 15% of patients with early syphilis treated with the recommended therapy will not achieve a two dilution decline in nontreponemal titer used to define response at 1 year following treatment, highlighting the complexity of interpreting serologic responses to treatment 1.
- Therefore, the patient should be monitored with regular serologic testing to assess for any further changes in RPR titer, rather than initiating or changing treatment based on this single change.
- If the patient's symptoms persist or recur, or if there is a subsequent fourfold increase in RPR titer, treatment or retreatment may be necessary, and a CSF analysis should also be performed to rule out neurosyphilis 1.
From the Research
Treatment for Increase in RPR Titer
- The increase in Rapid Plasma Reagin (RPR) titer from 1:1 to 1:2 indicates a potential treatment failure or reinfection in a patient with syphilis 2, 3.
- According to the studies, the preferred treatment for early syphilis is a single dose of 2.4 million units of benzathine penicillin G 4.
- However, for patients who are allergic to penicillin or have other contraindications, doxycycline is a recommended second-line agent 2, 3.
- A study comparing doxycycline and benzathine penicillin G for the treatment of early syphilis found that doxycycline is an effective agent, with no statistically significant differences in serological responses between the two groups 3.
- Another study found that single-dose benzathine penicillin G plus doxycycline achieved higher serologic responses than benzathine penicillin G alone in people with HIV 5.
- Azithromycin is not recommended as a first-line treatment due to concerns about resistance and variable efficacy 6.
Serological Response
- A serological response is defined as a 4-fold decline in RPR titers after treatment 4, 5.
- Patients who do not achieve a ≥ 4-fold serologic decline in their RPR titers 6-12 months after adequate therapy should be considered for further evaluation, including cerebrospinal fluid (CSF) examination 4.
- CSF examination should be performed in all persons with serologic evidence of syphilis infection and neurologic symptoms 4.