Q. A 56-year-old man presents to the emergency department with a four-week history of a productive cough with foul-smelling sputum, worsening shortness of breath, and chest pain. He has also experienced fever and chills, night sweats, and weight loss during this time. He has a 25-pack-year smoking history, drinks alcohol occasionally, and has no significant family history of lung diseases. His vital signs are as follows: temperature 100.9°F (38.3°C), blood pressure 130/85 mmHg, heart rate 95 beats/min, respiratory rate 22 breaths/min, and oxygen saturation 91% on room air. A chest radiograph reveals a thick-walled cavity with an air-fluid level in the right middle lobe with surrounding opacity. What is the most likely diagnosis for this patient?