Review Question - QID 109454

A 28-year-old woman presents to the emergency department with shortness of breath, cough with occasional blood-tinged sputum, and night sweats for the past week. She immigrated from Uganda 2 months ago. She denies any sexual activity or intravenous drug use. There is no history of cancer in her family. She currently lives in an apartment with several other female migrant workers. She received a vaccination against tuberculosis when she lived in Uganda. Her temperature is 99°F (37.2°C), blood pressure is 110/70 mmHg, pulse is 100/min, respirations are 20/min, and oxygen saturation is 94% on room air. Breath sounds are decreased in the left posterior lower and middle lung fields. Egophony is present on the left middle lung field. The remainder of the physical exam is unremarkable. A complete blood count and basic metabolic panel are obtained:

Serum:
Na+: 135 mEq/L
Cl-: 100 mEq/L
K+: 3.5 mEq/L
HCO3-: 26 mEq/L
BUN: 10 mg/dL
Glucose: 105 mg/dL
Creatinine: 0.6 mg/dL

Leukocyte count: 20,000/mm^3
Segmented neutrophils: 69 %
Bands: 10 %
Eosinophils: 2 %
Basophils: 1 %
Lymphocytes: 25 %
Monocytes: 3 %

Hemoglobin: 11 g/dL
Hematocrit: 33 %
Platelet count: 400,000/mm^3

An ECG reveals sinus tachycardia. Chest radiography is obtained in Figure A. Which of the following is the most appropriate next step in management?