A 52-year-old man notes nausea with abdominal dis- comfort after meals. On physical examination, there are no abnormal findings. Upper endoscopy is performed, and there are three ovoid nodules in the fundus and antrum ranging from 0.3 to 1.2 cm in size. They have rounded, smooth sur- faces. Biopsies are taken and on microscopic examination there are irregular, cystically dilated and elongated foveolar glands. Which of the following treatment strategies is most appropriate for his gastric lesions?