Question

how come helicobacter pylori cause a disease in the stomach?

Answer 1

Answer with discussion and explanation:

Helicobacter pylori is Gram negative bacteria that produces mucosal damage in stomach and cause gastritis and peptic ulcer. It is also considered to be associated with mucosa associated lymphoid tissue (MALT) lymphoma and gastric carcinoma.

Human acquire H.pylori through faeco-oral transmission. Upto 80% persons are colonised in developing countries due to poor socioeconomic conditions and family overcrowding.

* Key factor secreted by bacillus is urease, an enzyme that converts urea into ammonia, thus alkalinising the surroundings and hence protects it from lethal acidic gastric juice.This enzyme is responsible for survival of H.pylori in such harsh acidic environment where other bacteria cannot survive.

* Protease, vacuolating cytotoxin (Vac A) and phospholipase damage epithelial lining of gastric mucosa. Cytotoxin associated gene (CAG A) also induces inflammation and is a potential carcinogen.

* H.pylori causes an inflammatory response in gastric mucosa, with elevated level of cytokines like interleukins causing influx of inflammatory cells like neutrophils and macrophages. These inflammatory cells realese lysosomal enzymes, leukotrienes and reactive oxygen species thus further exaggerating the inflammatory cascade causing inflammation of gastric mucosa, termed as 'gastritis'.

* Production of ammonia by bacteria prevents D cells in the gastric antral glands from sensing the true level of acidity, leading to inappropriate release of somatostatin and increase in gastrin levels which stimulate parietal cells of gastric glands to produce excess acid, causing peptic ulcer.

Hence, H. pylori causes damage in the stomach to produce disease by above mentioned mechanisms.