A patient with secondary syphilis has a positive RPR titre of 1:64. After appropriate treatment with benzathine penicillin 2.4 MU IM, what RPR titre response at 6 months would be considered an adequate treatment response?
- A RPR titre falls by 4-fold or more (e.g. 1:64 to 1:16 or less) ✓
- B RPR becomes non-reactive (titre 0)
- C RPR titre falls by 2-fold (e.g. 1:64 to 1:32)
- D RPR must convert to VDRL negative
Explanation
Adequate serological response after treatment for secondary syphilis is defined as a 4-fold (two-dilution) or greater decline in non-treponemal titre (RPR or VDRL) within 6–12 months. A titre of 1:64 should fall to 1:16 or less. Failure to achieve this decline suggests treatment failure, re-infection, or HIV co-infection requiring CSF evaluation. Complete seroreversion (titre 0) may occur but is not required to confirm treatment success, especially in late-treated or previously treated patients (serofast state). VDRL and RPR are interchangeable but should not be compared directly.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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