Analysis of Helicobacter pylori genotypes in clinical gastric wash samples

Helicobacter pylori is a key factor in the development of gastric cancer; indeed, clearance of H. pylori helps prevent gastric cancer. However, the relationship between gastric cancer and the abundance and diversity of H. pylori genotypes in the stomach remains unknown. Here, we present, for the first time, a quantitative analysis of H. pylori genotypes in gastric washes. A method was first developed to assess diversity and abundance by pyrosequencing and analysis of single nucleotide polymorphisms in 23S ribosomal RNA (rRNA), a gene associated with clarithromycin resistance. This method was then validated using arbitrarily mixed plasmids carrying 23S rRNA with single nucleotide polymorphisms. Multiple strains were detected in many of 34 clinical samples, with frequency 24.3 ± 24.2 and 26.3 ± 33.8 % for the A2143G and A2144G strains, respectively. Importantly, results obtained from gastric washes were similar to those obtained from biopsy samples. The method provides opportunities to investigate drug resistance in H. pylori and assess potential biomarkers of gastric cancer risk, and should thus be validated in large-scale clinical trials.