Review Question - QID 109656

A 42-year-old man presents to the emergency department with a persistent cough. He has been coughing for the past week, has seen blood in his sputum, and experienced shortness of breath. On review of systems, the patient endorses fever and chills as well as joint pain. His temperature is 102°F (38.9°C), blood pressure is 159/98 mmHg, pulse is 80/min, respirations are 14/min, and oxygen saturation is 98% on room air. Laboratory values are ordered as seen below.

Hemoglobin: 12 g/dL
Hematocrit: 36%
Leukocyte count: 7,500/mm^3 with normal differential
Platelet count: 107,000/mm^3

Serum:
Na+: 138 mEq/L
Cl-: 101 mEq/L
K+: 4.2 mEq/L
HCO3-: 24 mEq/L
BUN: 32 mg/dL
Glucose: 99 mg/dL
Creatinine: 1.9 mg/dL
Ca2+: 10.0 mg/dL
AST: 11 U/L
ALT: 10 U/L

Urine:
Color: Amber, cloudy
Red blood cells: Positive
Protein: Positive

Additional tests are obtained including a CT scan of the chest as well as blood cultures; however, all of these are negative. Which of the following is the most appropriate next step in management?