A diagnostic algorithm for Helicobacter pylori detection and identification in gastric mucosal biopsies

Helicobacter pylori is a major etiological agent in gastritis, peptic ulcer disease, gastric adenocarcinoma, and MALT lymphoma. While gastric mucosal biopsies are the primary material for invasive diagnosis, a comprehensive diagnostic approach is needed. This study presents a diagnostic algorithm that facilitates not only H. pylori detection and identification but also, when necessary, the subsequent analysis of isolated microbial strains, e.g., virulence gene determinants or antibiotic resistance mutations. Having applied this algorithm from 2013 to 2024, we examined gastric biopsies from 610 patients (57% female, 43% male) aged 19–73 years with various gastrointestinal pathologies using culture and molecular methods. In our study, H. pylori detection rate by PCR vs culture examination (48.20% vs 32.3% respectively) in gastric biopsies was significantly higher. In gastric cancer, H. pylori DNA detection rate was minimal and amounted to 35.7%, which correlated with the lowest culture-based isolation rate (9.5%). Since vacA virulence gene is presented in all H. pylori strains, it was used as a marker for H. pylori detection in our study. Thus, the vacA gene was detected in 48.0% (258/537) biopsy samples. The cagA gene is not presented in all H. pylori strains and considered to be a high virulence marker. In addition, it was found out that the cagA gene was present in 47.3% H. pylori-positive cases. Notably, the proportion of cagA-positive isolates turned out to be minimal in chronic gastritis — 39.4%, in contrast to its level in peptic ulcer and gastric cancer comprising 77.3% (p < 0.001) and 72.7% (p = 0.029), respectively. Conclusion. The proposed diagnostic algorithm is applicable in microbiological practice for diagnosis, epidemiological monitoring, and research in H. pylori infections.