Review Question - QID 215158

A 50-year-old man presents to the primary care clinic for a work physical. He does not complain of any symptoms. His medical problems are hypertension and diabetes for which he takes lisinopril and metformin. He is allergic to penicillin. He does not smoke and drinks alcohol socially. He was recently diagnosed with cellulitis and is being treated with cephalexin and is 4 days into his treatment. The patient is a recent immigrant from Laos and has had poor medical follow-up. He states that he had many male and female sexual partners when he was in his 30's and rarely used protection. His temperature is 98.2°F (36.8°C), blood pressure is 118/76 mmHg, pulse is 84/min, and respirations are 18/min. On physical exam, a 2/6 early decrescendo diastolic murmur is auscultated over the left lower sternal border. A transthoracic echocardiogram reveals dilation of the aortic root. A serum test for antibodies against a spirochete is reactive. Which of the following is the most appropriate next step in the management of this patient?