Review Question - QID 214690

A 74-year-old man presents to the emergency department with 4 days of fevers. He currently resides at a nursing home and was in his normal state of health until experiencing unrelenting diaphoresis and chills for 4 days. He has a history of congestive heart failure, chronic back pain, and alcohol abuse disorder. His medications include lisinopril, furosemide, and tylenol. His temperature is 103.1°F (39.6°C), blood pressure is 130/60 mmHg, pulse is 73/min, and respirations are 19/min. On exam, he is alert and oriented but appears diaphoretic and fatigued. His lungs are clear to auscultation, and there are no rashes. He is found to have pyuria and is started on ceftriaxone. Twelve hours later, his temperature is 101.8°F (38.8°C), he demands that he be allowed to return home, and he gets agitated when the nurse does not allow him to leave his bed. He starts complaining about a parrot in his bathroom. One hour later he politely asks when he will receive lunch. Which of the following is the most likely diagnosis?