H. pylori is a spiral, gram-negative, microaerobic bacterium. Almost half of the population is infected for life, and the site of infection is mainly in the stomach and duodenal bulb. Accompanying symptoms include, pyloric duct ulcers, stomach pain, bloating, nausea, acid reflux, and stomach pain. Examination items: 1.Bacterial culture The gastric mucosa specimen is directly seeded onto solid medium or ground into homogenate and then inoculated. Place under micro-oxygen conditions, relative humidity of 90% or more, incubate at 37℃ for 48-72h and observe the results, at least based on smear staining microscopy, urease, peroxidase and oxidase identification. 2.Gastric biopsy mucosal smear The mucosal surface of the biopsy was directly applied to a clean slide, and after natural drying Gram staining or complex red staining, oil microscopy observation. 3, tissue section staining Gastric mucosal biopsy specimens (multi-point sampling is desirable) are embedded vertically in sections and observed under oil microscopy or fluorescence microscopy using Warthin-Starry and Centa silver staining or HE staining, Giemsa staining, fluorescein acridine orange staining, miparin staining and unlabeled antibody PAP staining. 4.Urease test Hp has high urease activity and can decompose urea to produce NH4, so by measuring the presence or absence of NH4, we can indirectly determine whether there is Hp infection. There are pH indicator method, analytical chemistry method and isotope labeling urea test and other methods. 5.14C urea breath test The patient is given 14C urea orally, and if there is Hp infection, there is 14CO2 in the gas exhaled by the patient after 20min, and there is no 14CO2 exhaled if there is no Hp infection. This test is safe, accurate and reproducible, but it is not easy to promote its application due to equipment and other reasons. 6.Serological test Apply ELISA method to detect anti-HpIgG or anti-HpIgA in serum or saliva, which is specific and sensitive index. 7, polymerase chain reaction (PCR) technology can detect Hp in gastric juice, gastric mucosa, saliva, the positive rate is higher than the urease method. 8, in situ identification can apply monoclonal antibodies for immunohistochemical detection, Hp-specific probes or primers for in situ hybridization and PCR detection. Tissue section staining: gastric mucosal biopsy specimens (multi-point sampling is desirable) are embedded vertically in sections and observed under oil microscopy or fluorescence microscopy using Warthin-Starry and centa silver staining or HE staining, Giemsa staining, fluorescein acridine orange staining, miparin staining and label-free antibody PAP staining.