This study is planned to reveal the occurrence rate of H.pylori infection in ambulatory settings' patients in Russia and to compare the occurrence rates in different years in treatment-naïve and previously treated subjects.

Inclusion Criteria:

• willingness to participate (based on the signed informed consent form);
• age older than 12 y.o. (for subjects younger than 18 y.o. written informed consent of a legal representative was obligatory);
• availability of demographic data and medical history, including previous treatment for H.pylori infection

For subjects of "treatment-naïve" group:

• no previous treatment for H.pylori infection in the anamnesis;
• at least 6 weeks after previous use of any antimicrobial agents for any reason;
• at least 2 weeks' time frame free of use of proton pump inhibitors, other anti-secretory agents and bismuth preparations.

For "Previously treated" group of subjects:

• infection caused by H.pylori established earlier and
• not less than 6 weeks after the end of eradication therapy with at least 2 antibiotics and a proton pump inhibitor for at least 7 days, based on a patient's report

Exclusion Criteria:

• history of surgery on chest, stomach, gut (excluding appendectomy or laparoscopic cholecystectomy performed more than 6 month before the enrolment);
• advanced stage of chronic obstructive pulmonary disease,
• allergies to citruses,
• pregnant and breastfeeding women.

Ambulatory subjects, referred to perform urea breath test (UBT) and who gave written informed consent for the use of their data for research purposes are aligible for the study.

Depersonalised data will be available upon request

Upon request

reasonable request to the principal investigator