Helicobacter pylori (HP) is a gram-negative pathogenic bacterium that specifically colonizes in the gastric epithelium and causes chronic gastritis, peptic ulcer disease, and/or gastric malignancies. Persistent infection can cause inflammation and gastritis that may lead to carcinogenesis. Transmission is still not entirely clarified, but human-to-human spread through oral-oral or fecal-oral route is thought to be the most plausible. The prevalence of HP infection varies between different geographical regions; generally, the prevalence is about 30% in developed and up to 80% in developing countries. Although HP may sometimes be eradicated by antibiotics given for other infections, infection usually persists life-long unless specific combination antibiotic therapy is taken.
