Q. A 45-year-old man who is an alcoholic and chronic smoker has presents to the clinic accompanied by his wife with a 5-week history of fatigue, shortness of breath and fever. He is also complaining of a productive cough. His wife adds that every time he coughs “his breath smells awful!” afterwards. Past medical history includes hypertension and clinical depression. His examination shows dullness to percussion over the right upper lung field on chest auscultation. A chest x-ray reveals a lung cavity with an air-fluid level. Which of the following is the most appropriate next step for management?