Helicobacter pylori bacteria is a rod-shaped, corkscrew-like bacterium that lives in the stomach and upper intestinal tract of infected people, and contributes to a variety of digestive system diseases.
It has recently been identified as the primary cause of human gastric and duodenal ulcers. H. pylori, like many pathogenic bacteria, is Gram-negative, a term that describes how the bacterium reacts with a particular type of stain.
Gram staining is a technique used by medical laboratories to help identify bacteria when they are isolated from diseased tissue. The technique provides information about the outer membrane of the bacterium, which reveals much about its biology and potential for causing disease. Unlike Gram-positive bacteria, Gram-negative bacteria contain an outer wall called the lipopolysaccharide, or LPS, layer. This serves as a protective layer through which materials must pass before they reach the cell.
Gram-negative bacteria differ from one another in the composition of the LPS, particularly in the specific type of polysaccharide present in the membrane. In many Gram-negative species, this layer is toxic and responsible for some of the symptoms of an infection; hence components of the LPS layer are sometimes called endotoxins.
Beneath the LPS outer wall is a small, protective space called the periplasmic space, thought to be one way that H. pylori is able to survive in the stomach. Beneath that is a layer of peptidoglycan, a compound composed mostly of protein and polysaccharide, which is thicker in Gram-negative bacteria than Gram-positive species.
So this type of Helicobacter pylori bacteria is very dangerous for any living person because they convert themselves into ulcer and other stomach diseases.