Postexposure Prophylaxis for HIV Infection

A 24-year-old man presents to an outpatient clinic, reporting that 36 hours previously he had receptive anal intercourse without the use of a condom with an anonymous male partner who was known to have had sex with other men. The patient is known to the clinical practice and has had several negative tests for human immunodeficiency virus (HIV) infection, most recently 6 months previously. How should he be evaluated and treated?