A 40-year-old man has an RPR reactive at 1:4 with a positive TPPA. He is completely asymptomatic and cannot recall any episode of genital ulceration or rash. Physical examination is normal. His last documented negative syphilis screen was more than three years ago. What is the recommended treatment?

• A Benzathine penicillin G 2.4 million units IM as a single dose
• B Doxycycline 100 mg twice daily for twenty-eight days
• C Procaine penicillin G 1.2 million units IM daily for fourteen days
• D Benzathine penicillin G 2.4 million units IM weekly for three doses ✓

Explanation

Syphilis of unknown duration exceeding two years, or documented late latent syphilis, requires three weekly doses of benzathine penicillin G 2.4 million units IM, because treponemes divide slowly and penicillin acts only on dividing organisms. A single dose suffices only for primary, secondary and early latent syphilis of less than one year duration. Procaine penicillin for fourteen days is used for neurosyphilis, and doxycycline is reserved for penicillin-allergic patients. Indian convention uses a two-year cutoff between early and late latency.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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