An otherwise healthy 45-year-old man comes to the physician because of a 3-week history of progressive epigastric
heartburn and a 4.5-kg (10-lb) weight loss. The pain tends to be more severe at night and occurs 1 to 3 hours after
meals during the day. He has had similar episodes with lesser intensity during the past year. Abdominal examination
shows tenderness to deep palpation. Test of the stool for occult blood is positive. Endoscopy shows a bleeding 3-cm
ulcer in the antrum of the stomach. A photomicrograph of Steiner silver-stained tissue (400x) from a biopsy of the
gastric mucosa adjacent to the ulcer is shown. Which of the following processes is most likely to be involved?
(A) Elaboration of proteases and urease with local tissue destruction
(B) Hyperacidity and gastric ulcer development
© Ingestion of preformed toxins in contaminated well water
(D) Spirochete invasion of gastric cells