A patient with early syphilis is treated with benzathine penicillin G 2.4 million units intramuscularly. At the 6-month follow-up visit, quantitative VDRL titer has declined by two dilutions from the baseline titer of 1:32 to 1:8. What does this change indicate?

• A Treatment failure; retreatment with benzathine penicillin is required
• B Probable reinfection; the decline is too slow for a cured patient
• C Adequate treatment response; a fourfold decline by 6 months is expected ✓
• D Serofast state; lifelong non-treponemal antibody persistence is now established

Explanation

After treatment of early syphilis, a fourfold decline in non-treponemal antibody titer (for example, from 1:32 to 1:8) by 6 months indicates adequate treatment response. A decline of two dilutions corresponds to a fourfold reduction. Treatment failure is suspected if titers fail to decline fourfold by 6 to 12 months or if they rise. A serofast state is defined as a persistent low titer that remains stable for 12 months or more, not at 6 months.

Reference: Sexually Transmitted Infections, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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