Fig. 1

Helicobacter pylori (HP) and gastric/extra-gastric diseases. A Electron micrograph of HP, a spiral-shaped bacterium with multiple polar flagella at a single pole; the length is 2.5–4 μm and diameter is 0.3–0.5 μm. B HP features and diseases in the stomach. C HP-related extra-gastric diseases can be categorized into four groups based on the pathophysiology