Community-acquired pneumonia

A 67-year-old woman with mild Alzheimer's disease who has a 2-day history of productive cough, fever, and increased confusion is transferred from a nursing home to the emergency department. According to the transfer records, she has had no recent hospitalizations or recent use of antibiotic agents. Her temperature is 38.4°C (101°F), the blood pressure is 145/85 mm Hg, the respiratory rate is 30 breaths per minute, the heart rate is 120 beats per minute, and the oxygen saturation is 91% while she is breathing ambient air. Crackles are heard in both lower lung fields. She is oriented to person only. The white-cell count is 4000 per cubic millimeter, the serum sodium level is 130 mmol per liter, and the blood urea nitrogen is 25 mg per deciliter (9.0 mmol per liter). A radiograph of the chest shows infiltrates in both lower lobes. How and where should this patient be treated?