Helicobacter pylori

Helicobacter pylori (/ˌhɛlɪkɵˈbæktər pˈlɔər/), previously named Campylobacter pylori, is a Gram-negative, microaerophilicbacterium found in the stomach, and may be present in other parts of the body, such as the eye.[1][2][3] It was identified in 1982 by Australian scientists Barry Marshall and Robin Warren with further research led by British scientist Stewart Goodwin, who found that it was present in patients with chronic gastritis and gastric ulcers, conditions not previously believed to have a microbial cause. It is also linked to the development of duodenal ulcers and stomach cancer. However, over 80% of individuals infected with the bacterium are asymptomatic and it may play an important role in the natural stomach ecology.[4]

More than 50% of the world’s population harbor H. pylori in their upper gastrointestinal tract. Infection is more prevalent in developing countries, and incidence is decreasing in Western countries. H. pylori’s helical shape (from which the generic name is derived) is thought to have evolved to penetrate the mucoid lining of the stomach.[5][6]

gastrointestinal tract

In zoology, the gut, also known as the alimentary canal or gastrointestinal tract, is a tube by which bilaterian animals (includinghumans) transfer food to the digestion organs.[1] In large bilaterians, the gut generally also has an exit, the anus, by which the animal disposes of solid wastes. Some small bilaterians have no anus and dispose of solid wastes by other means (for example, through the mouth).[2]

Animals that have guts are classified as either protostomes or deuterostomes, as the gut evolved twice, an example of convergent evolution. They are distinguished based on their embryonic development. Protostomes develop their mouths first, while deuterostomes develop their mouths second. Protostome include arthropods, molluscs, and annelids, while deuterostomes include echinoderms andchordates.

The gut contains thousands of different bacteria, but humans can be divided into three main groups based on those most prominent.[3]

For more specific information on digestive organs, see specialized organs and behaviours.