Helicobacter pylori is a small, curved, microaerophilic, gram-negative, rod-shaped bacterium.
Believed to be fecal-oral or possibly oral-oral.
Common worldwide. Estimated prevalence is 70% in developing countries and 30%–40% in the United States and other industrialized countries
Usually asymptomatic, but H. pylori is the major cause of peptic ulcer disease and gastritis, which presents as gnawing or burning epigastric pain. Less commonly, symptoms include nausea, vomiting, loss of appetite, or bleeding.
Fecal antigen assay, urea breath test, rapid urease test, or histology of biopsy specimen. A positive serology indicates present or past infection.