Helicobacter pylori (H. pylori) is a type of bacteria that can infect the human digestive system. It is a spiral-shaped, microaerophilic bacterium that is approximately 2.9 to 4.0 μm long and 1.2 to 1.8 μm wide. H. pylori is Gram-negative and non-spore-forming, and belongs to the genus Helicobacter.
H. pylori is a motile, spiral-shaped organism with an asymmetric, flagellated, and non-sessile cell body that rotates about an axis parallel to its long axis. It has a single polar flagellum that is sheathed, extending the length of the cell body and coiled in a helix that is often tightly packed into a discoid cluster, with the flagellar hook at the end of the flagellum terminating in a short, stubby extension.
H. pylori is a slow-growing bacterium that thrives in an anaerobic environment with low acidity and high levels of oxygen within the mucous layer of the human stomach. It is able to survive in this environment due to its ability to generate energy through fermentation reactions and respiratory processes that occur within the periplasmic space of the cell wall.