A 59-year-old man has had nausea and vomiting for several months. He has experienced no hematemesis. On physical examination, there is no abdominal tenderness, and bowel sounds are present. Upper gastrointestinal endoscopy shows erythematous areas of mucosa with thickening of the rugal folds in the gastric antrum. The microscopic appearance of a gastric biopsy specimen with a Steiner silver stain is shown in the figure. Which of the following toxins from these organisms is most likely to be present on the luminal surface?
- Cysteine proteinase
- Heat-stable enterotoxin
- Shiga toxin
- Vacuolating toxin
- Verocytotoxin