From the Guidelines
A positive treponema test with a negative RPR suggests a past, successfully treated syphilis infection or very early syphilis, and treatment with Benzathine Penicillin G 2.4 million units IM as a single dose is recommended if there's no documented history of adequately treated syphilis. This pattern occurs because treponemal tests typically remain positive for life after infection, while non-treponemal tests like RPR can become negative after treatment 1. The sensitivity of VDRL in early latent syphilis ranged from 82.1–100% 1, and the sensitivity of RPR in primary syphilis ranged from 72.5–92.7% 1. If penicillin allergy exists, doxycycline 100mg twice daily for 14 days is an alternative. Sexual partners should be evaluated and treated if exposed within 90 days. This discordant pattern requires clinical correlation with patient history, as it could represent either treated syphilis or early infection where the RPR hasn't yet become reactive. Follow-up testing in 2-4 weeks may be helpful if early syphilis is suspected, as the RPR may become positive during this time. Patients with HIV should receive the same treatment but may require closer follow-up.
Some key points to consider:
- Treponemal tests typically remain positive for life after infection 1
- Non-treponemal tests like RPR can become negative after treatment 1
- The sensitivity of VDRL in early latent syphilis ranged from 82.1–100% 1
- The sensitivity of RPR in primary syphilis ranged from 72.5–92.7% 1
- Treatment with Benzathine Penicillin G 2.4 million units IM as a single dose is recommended if there's no documented history of adequately treated syphilis
- If penicillin allergy exists, doxycycline 100mg twice daily for 14 days is an alternative
- Sexual partners should be evaluated and treated if exposed within 90 days
- Patients with HIV should receive the same treatment but may require closer follow-up.
It's also important to note that the performance characteristics of nontreponemal antibody tests, such as RPR, can vary depending on the stage of syphilis and other factors 1. Therefore, clinical correlation and follow-up testing are crucial in interpreting the results of these tests.
From the Research
Treponema Reactive Presumptive, RPR Non-Reactive
- The patient's test results show a treponema reactive presumptive, but the RPR (Rapid Plasma Reagin) test is non-reactive 2, 3, 4, 5, 6.
- This combination of results can be seen in early syphilis, where the treponema test detects the presence of antibodies against the syphilis bacteria, but the RPR test has not yet become reactive 2, 4.
- The RPR test measures the level of antibodies against syphilis in the blood, and a non-reactive result can indicate that the infection is still in its early stages or that the patient has been treated successfully 3, 5.
- However, it is also possible that the patient has a false-negative RPR result, which can occur in some cases of syphilis, especially in patients with HIV 6.
Treatment and Management
- The treatment of choice for early syphilis is a single dose of 2.4 million units of benzathine penicillin G, which is effective in curing the infection in most cases 2, 3, 4, 5.
- Azithromycin is an alternative treatment option, but its use is limited by the emergence of resistance to the drug 4, 5.
- In patients with HIV, the treatment response to benzathine penicillin G may be poorer, and the addition of doxycycline to the treatment regimen may improve serologic outcomes 6.
Serologic Response
- The serologic response to treatment is an important indicator of the effectiveness of therapy, and a decline in RPR titers is expected after successful treatment 2, 3, 4, 5, 6.
- A 4-fold decline in RPR titers at 12 months after treatment is considered a satisfactory response to therapy 6.
- Factors that can influence the serologic response to treatment include the baseline RPR titer, the presence of HIV, and the use of adjunctive therapy such as doxycycline 6.