Review Question - QID 210968

A 48-year-old man presents to his primary care physician with diarrhea and weight loss. He states he has had diarrhea for the past several months that has been worsening steadily. The patient recently went on a camping trip and drank unfiltered stream water. Otherwise, the patient endorses a warm and flushed feeling in his face that occurs sporadically. His temperature is 97.2°F (36.2°C), blood pressure is 137/68 mmHg, pulse is 110/min, respirations are 14/min, and oxygen saturation is 98% on room air. A physical exam is notable for a murmur heard best over the left lower sternal border and bilateral wheezing on a pulmonary exam. Which of the following is the most appropriate initial step in management?