H pylori is Helicobacter Pylori a type of bacteria that causes ulcers and if not treated eventually cancer. H pylori ab is the antibody produced by the body to counteract H pylori antigens. The presence of H pylori ab would indicate the person has, or has had, H pylori. (Spelling of Helicobacter is correct and at the 3rd or 4th time of mentioning should be recognised as such, moderator please note)