Culture and Molecular Identification of Helicobacter pylori in Drinking Water from Areas of High and Low Incidence of Gastric Cancer in Costa Rica

Background: Most patients infected with Helicobacter pylori show no clinical symptoms. Nonetheless, approximately 10% to 20% of these patients will develop peptic ulcers and 1% will develop gastric cancer. The International Agency for Cancer Research has classified Helicobacter pylori as a Group 1 carcinogen. Materials and Methods: Drinking water samples from 20 cantons situated in areas of low and high incidence of gastric cancer in Costa Rica were analyzed. Water samples were concentrated and the nitrocellulose filter was cultivated for later molecular identification of Helicobacter pylori using the glmM marker. The tumor necrosis factor-alpha inducing protein (Tipalpha TNF-α) was used as a pathogenicity marker of the strains found followed by the sequencing of two products. Information on water management by aqueduct operators was collected in order to establish statistical relationships. Results: A total of 112 water samples were analyzed. Successful cultivation and molecular identification using the glmM marker was achieved in 39% of samples from areas of high incidence and in 7.5% of samples from areas of low incidence. Two glmM gene PCR products were sequenced and confirmed as true positives. Conclusions: The highest prevalence rate of Helicobacter pylori was found in water from areas with a high incidence of gastric cancer. Additionally, significant statistical correlations were established among environmental conditions, drinking water management and incidence of gastric cancer.