Q. A 58-year-old male presents to the clinic after having gastric surgery a month ago. He states he feels well except an occasional cough and shortness of breath that started a week ago. Past medical history includes chronic kidney disease and hypertension. He has no history of recent illness. On examination, his blood pressure is 105/65 mmHg, heart rate 120/min, respiratory rate is 28/min. Laboratory tests reveal an estimated glomerular filtration rate of 20 mL/min/1.73 m2. CT angiography with contrast shows an opacity with a consolidated border and pleural effusion on the right lung. What would be the drug of choice for initial treatment of this patient?