Both the acid and the bacteria irritate the lining and cause a sore, or ulcer. H. pylori is able to survive in stomach acid because it secretes enzymes that neutralize the acid. Once there, the bacterium's spiral shape helps it burrow through the mucous lining. Pain is the most common symptom. The pain usually a dull, gnawing ache.
Some people experience only very mild symptoms, or none at all.
Sharp, sudden, persistent stomach pain. Bloody or black stools. Bloody vomit or vomit that looks like coffee grounds. An upper GI series is an x-ray of the esophagus, stomach, and duodenum. The patient is lightly sedated, and the doctor carefully eases the endoscope through the patient's mouth and down the throat to the stomach and duodenum.