A 24-year-old woman is diagnosed with neurosyphilis after presenting with stroke-like symptoms and a positive treponemal enzyme immunoassay (EIA) and a positive Rapid Plasma Reagin (RPR) test (titer of 1:128). A lumbar puncture is performed with cerebrospinal fluid analysis that shows protein of 64 mg/dL, white blood cell count of 18 (80% lymphocytes), and a positive cerebrospinal fluid Venereal Disease Research Laboratory (VDRL) titer of 1:64. Tests for other causes of stroke, as well as an HIV test, are negative. She has a 2-year history of exchanging sex for money, but has never been tested or treated for syphilis. She denies any history of allergic reactions to antibiotics.