A reactive VDRL titer of 1:64 is found in a 28-year-old man without symptoms. He is confirmed HIV-positive with CD4 count 350 cells/μL. CSF is examined to exclude neurosyphilis. CSF shows: WBC 12 lymphocytes, protein 55 mg/dL, CSF VDRL reactive (1:2). The MOST appropriate treatment is:
- A Benzathine penicillin G 2.4 million units IM single dose (same as latent syphilis treatment)
- B Doxycycline 100 mg orally twice daily for 28 days (equivalent to benzathine for neurosyphilis)
- C Aqueous crystalline penicillin G 18–24 million units/day IV for 10–14 days ✓
- D Ceftriaxone 2g IV daily for 10–14 days as first-line treatment for neurosyphilis in HIV patients
Explanation
Neurosyphilis requires high-dose parenteral penicillin to achieve treponemicidal levels in the CSF — benzathine penicillin IM does NOT reliably penetrate the CSF and is inadequate for neurosyphilis. The standard treatment is aqueous crystalline penicillin G 18–24 million units per day (3–4 million units IV every 4 hours) for 10–14 days. Alternatively, procaine penicillin G 2.4 million units IM once daily plus probenecid 500 mg orally QID for 10–14 days is acceptable. Ceftriaxone 2g IV/IM daily for 10–14 days is an alternative but evidence is less robust. Doxycycline does not achieve adequate CNS penetration for neurosyphilis. HIV-positive patients with neurosyphilis are treated with the same regimen as HIV-negative patients.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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