A 60 year old woman presents with dyspnea and a cough productive of yellow-green sputum for 3 days.

During the preceding 2 weeks, she had also experienced a non-productive cough and myalgia. There was no history of hemoptysis or fever.

She was diagnosed with diabetes mellitus 3 years ago, which is well controlled on diet alone. She is a heavy smoker, with a smoking history of 30 pack years.

She currently works as a volunteer in a homeless shelter.