Treatment of Late Latent Syphilis — More Than 2 Years Since Acquisition (Non-Pregnant)
This protocol applies to late latent syphilis in a non-pregnant patient: serologically confirmed syphilis without active symptoms, where infection was acquired more than two years previously. Correct staging is the critical first step, as it determines which treatment regimen is indicated.
Latent syphilis is defined as late once more than two years have elapsed since acquisition. Where a confirmed treatment history is absent, staging should be based on available clinical and serological evidence. This distinction from early latent disease directly governs the recommended treatment intensity.
Management is built around a multi-dose injectable penicillin regimen given over several weeks. Oral antibiotic courses are available as alternative options. The complete regimen, full list of alternatives, and their sequencing are set out in the structured protocol.
The primary target is a four-fold decrease in the RPR titre following treatment. Serological follow-up with RPR testing is performed at 3, 6, and 12 months, continuing until the RPR reaches negative or a serofast state is confirmed.
The latent stage is defined as early within 2 years, and late thereafter (ending with the development of tertiary disease).
For those without a confirmed history of treatment, syphilis should be staged as early (within 2 years of acquisition) or late (more than 2 years since acquisition) in order to determine the recommended penicillin regimen.
Benzathine penicillin 2.4 MU IM weekly for 3 weeks (three doses).
Doxycycline 100 mg PO BD for 28 days.
Amoxycillin 2 g PO three times daily (TDS) PLUS probenecid 500 mg QDS for 28 days.
Ceftriaxone 2 g IM or IV for 10–14 days.
It may take a number of months for the non-treponemal titres to drop 4-fold following treatment, particularly following treatment of re-infection.
Clinical and serological (RPR tests) follow-up is recommended at 3, 6 and 12 months then, if indicated, six monthly until RPR negative or serofast.
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