Q. A 70-year-old male is brought to the emergency department by his son. The son is extremely worried as his father as he has not been himself since this morning. He is drowsy and mumbles when he tries to speak. The patient was able to carry out his daily tasks independently before the onset of these symptoms. The patient has had a fever and cough for the past 5 days. His past medical history includes coronary artery disease. In addition, the patient has history of smoking. Family history is unremarkable. On examination, temperature is 102.2°F, blood pressure 120/78 mmHg, heart rate 99/min, respiratory rate 24/ min, and SpO2 is 92 % on room air. On chest examination, crackles are audible and breath sounds are decreased over the right lung base. Chest x-ray revels alveolar infiltrates in the right lung base. Lab results are as follows hemoglobin 12 g/dL, leukocytes 13,000/mm3, blood urea nitrogen 24 mg/dL, and creatinine: 1.1 mg/dL. What would be the most likely diagnosis?