Molecular fingerprinting of Helicobacter pylori strains from duodenal ulcer patients.

Aims: To characterize the molecular fingerprinting of Helicobacter pylori population isolated in duodenal ulcer patients treated with triple therapy. Methods and Results: Gastric biopsy specimens from corpus and antrum, were cultured for H. pylori isolation. Helicobacter pylori eradication was evaluated after 4 and 16 weeks. DNAs of all isolates were characterized by random amplified polymorphic DNA typing and cagA gene was also detected. After the therapy, five patients harboured the microorganism at 4 weeks and two of them remained H. pylori positive at 16 weeks. The analysis of DNA fingerprinting of strains isolated from antrum and corpus of patients susceptible to treatment, showed similar patterns. Instead, when the therapy was not effective, strains isolated from sequential biopsies from initial and after 4 and 16 weeks, showed distinct fingerprintings and retained the cagA status, over time. Conclusions: The drugs used for therapy could exercise an effect in genotypical rearrangement among H. pylori cells. Significance and Impact of the Study: The variableness among H. pylori strains represents a way to challenge environmental stress.