Abstract: | The presence of genetic markers of vacA-positive strains with s1/s2 subtype (76%) with a high proportions (84%) of mixed genotype and detection in a breath air the ammonia at significantly high concentrations, have been found to be the specific features of H. pylori infection in patients with a severe course of duodenal ulcer. A low level of specific IgG antibodies, the growth of immunological inflammation markers and the depression of humoral immunity have been established. |