The definition of gastritis is based on the histological features of the gastric mucosa. This is not the erythema observed during gastroscopy, and there are no specific clinical manifestations or symptoms that determine it. The modern classification of gastritis is based on time (acute and chronic), histological features, anatomical distribution and the main pathological mechanisms. Acute gastritis will develop into chronic if left untreated. Helicobacter pylori (H. pylori) is the most common cause of gastritis worldwide. However, from 60 to 70% H. pylori-negative subjects with functional dyspepsia or non-erosive gastroesophageal reflux were also found to have gastritis. H. pylori-negative gastritis is considered when a person meets all four of these criteria: negative triple staining of biopsies of the gastric mucosa, no history of treatment of H. pylori. In these patients, the cause of gastritis may be associated with tobacco smoking, alcohol consumption and / or the use of nonsteroidal anti-inflammatory drugs (NSAIDs) or steroids. Other causes of gastritis include autoimmune gastritis associated with antibodies of serum anti-parietal and anti-internal factor; organisms other than H. pylori, such as Mycobacterium avium intracellulare, Herpes simplex and Cytomegalovirus; gastritis caused by acid reflux; Rare causes of gastritis include collagen gastritis, sarcoidosis, eosinophilic gastritis and lymphocytic gastritis. The clinical picture, laboratory studies, gastroscopy, as well as histological and microbiological examination of tissue biopsies are important for the diagnosis of gastritis and its causes. Treatment of gastritis caused by H. pylori leads to the rapid disappearance of polymorphic-nuclear infiltration and a decrease in chronic inflammatory infiltrate with gradual normalization of the mucous membrane. Other types of gastritis should be treated based on their etiology
