A 42-year-old man with HIV presents to the clinic to reestablish care after a several-year absence. He feels well and has no complaints, though syphilis screening shows a positive enzyme immunoassay antibody (EIA) and a rapid plasma reagin (RPR) titer of 1:32. Records show the most recent syphilis testing was obtained 3 years ago and the EIA was negative. He reports condomless sex with several male partners over the past 2 years, but none were known to have syphilis. He has no symptoms and the physical examination is normal, including a normal neurologic examination. He has no medication allergies.