77-year-old resident of a skilled nursing care facility is brought to the emergency department because of fever and vomiting for the past 2 days. She is alert but is
unable to give a history. She asks repeatedly for a drink of water. Her temperature is 38.60C (1 01.50F), and blood pressure is 100/60 mm Hg. Examination shows a
distended, nontender abdomen with sparse high-pitched bowel sounds. A supine x-ray of the abdomen shows multiple dilated loops of small bowel and gas within the
small-bowel lumen and within the liver. Which of the following is the most likely cause of these findings?