A 66-year-old male is brought to your office by his wife with complaint of productive cough, fever, and chills for the past 2 days. The patient lives with his wife and is retired. PMH is significant for DM, for which he takes insulin; CHF, with an ejection fraction of 40%; and a history of renal insufficiency. He is alert and oriented. There is no history of smoking or alcohol use. On examination, the patient is lethargic. He has crackles over the left lower lung. CVS examination is normal. Vitals: Temperature = 39.61°C, BP = 82/54, HR = 128, RR = 24. O2 saturation on room air is 97%. CXR shows infiltrates and consolidation in the left lower lobe of the lung. Lab results show WBC 15, hematocrit 36, Na 142, glucose 167, BUN 36, creatinine 1.5. Lactate is elevated. What is the likely diagnosis in this patient?