The clinical management of H. pylori infection depends essentially on two factors, prevalence and local resistance. In Germany, only limited data from rather small cohorts currently exist regarding both factors. Knowledge of the current prevalence (accounting for socioeconomic factors and age) is important for the selection of suitable detection methods, as this influences the positive and negative predictive value of the respective diagnostic methods. Current data on antibiotic resistance are essential for efficient therapy. In this clinical study, we will collect data on the frequency and severity of H. pylori infections and then, after endoscopic examination, on antibiotic resistance. Knowledge of the resistance situation is necessary for the selection of suitable therapeutic regimens. Furthermore, molecular methods for resistance detection are to be compared with conventional microbiological methods in order to be able to detect resistance more quickly. Furthermore, we aim to identify specific parameters for early detection of patients at particularly high risk of gastric cancer or with precancerous lesions due to infection. The aim is to identify carcinogenesis-relevant factors such as gastric microbiome signatures that will make it possible to identify patients who are most likely to benefit from prophylactic eradication therapy in terms of risk stratification.