Q. A 32-year-old woman arrives at the emergency department with a 48-hour history of severe nausea, vomiting, and watery diarrhea. She states she has had no appetite and complains of abdominal cramping, primarily in the lower quadrants. She denies any recent travel but mentions attending a local food fair two days before the onset of symptoms. She does not recall anyone else having the same symptoms. The patient does not take any medications regularly, and she has no known allergies. On physical examination, the patient appears pale and anxious. Her vital signs show Blood pressure of 100/70 mmHg, pulse rate of 110 bpm, respiratory rate of 20 breaths per minute, temperature of 100.4°F (38°C), and oxygen saturation of 97% on room air. Her oral mucosa appears dry, and her skin turgor is slightly reduced. Abdominal examination reveals mild distension with diffuse tenderness, and hyperactive bowel sounds are audible. Laboratory tests show a white blood cell count of 6,000/uL, serum sodium of 135 mEq/L, potassium of 3.5 mEq/L, and chloride of 100 mEq/L. The patient’s blood urea nitrogen (BUN) is elevated at 25 mg/dl, and creatinine is at 1.2 mg/dl. A stool sample is positive for fecal leukocytes. What is the most appropriate next step in management?