A 68-year-old woman presents to the emergency department accompanied by her daughter, who reports her mother has experienced worsening confusion, profound weakness, and lethargy over the past 3 days. The daughter notes the patient has had a productive cough and felt "feverish" for the past week, leading to a marked decrease in her oral intake. Her medical history is significant for type 2 diabetes mellitus and hypertension. Her medications include metformin and lisinopril. She does not smoke or drink alcohol. She appears profoundly lethargic and is oriented only to person. She is febrile with a temperature of 100.8 °F (38.2 °C). Her blood pressure is 96/60 mmHg with a heart rate of 115 bpm, and her respiratory rate is 20 breaths per minute.