Problem: 55 year old woman seen in clinic complaining of cough, fever, and purulent sputum for 3 days. Past medical history of osteoporosis, hypertension and diabetes type 2. Currently on hydrochlorothiazide, alendronate and metformin. On exam, she is thin but appears healthy. Temperature is 102F, pulse 108 bpm, blood pressure 122/78 mm Hg, and respirations are 22 breaths/min. Bronchial breath sounds are heard over the left lower lung fields. There is dullness to percussion over left lower lung. Cardiovascular exam and abdominal exam are unremarkable. CBC reveals white count of 14,000 cells/mm3. Chest X-ray reveals left lower lobe infiltrate.
1. What is most likely diagnosis and most likely causative organism?