A 5-year-old boy has had diarrhea for a week, averaging six low volume stools per day, which appear mucoid and sometimes blood-tinged. On physical examination, his temperature is 37.4deg C. He has mild lower abdominal tenderness, but no masses. A stool culture is positive for Shigella sonnei. Which of the following microscopic findings would most likely be seen in this child's colon?

Shigellosis results in bloody dysentery because Shigella is highly virulent, resistant to gastric acid, and can invade and destroy the colonic mucosa. There is typically a mononuclear infiltrate extending to the lamina propria, with a neutrophilic exudate overlying the ulcerated areas. Stricture formation may follow intestinal tuberculosis. Intranuclear inclusions in enterocytes point to infection with DNA viruses, such as herpesviruses like cytomegalovirus. Granulomatous inflammation may be seen with granulomatous colitis (Crohn disease) and intestinal tuberculosis (rare). An increase in mononuclear inflammatory cells may be seen with milder forms of enterocolitis caused by viruses, Giardia, and Salmonella spp.