Q. A 42-year-old woman presents to the emergency department with a three-week history of worsening cough, producing foul-smelling sputum, shortness of breath, and chest pain. She has also been experiencing fever, chills, night sweats, and weight loss. She has a 20-pack-year smoking history and drinks alcohol socially. She has no significant family history of lung diseases. Her vital signs are as follows: temperature 101.2°F (38.4°C), blood pressure 125/80 mmHg, heart rate 100 beats/min, respiratory rate 24 breaths/min, and oxygen saturation 92% on room air. A chest radiograph reveals a thick-walled cavity with an air-fluid level in the right lower lobe. Which is the most common organism associated with this patient's condition?