Helicobacter pylori in water systems for human use in Mexico City

Helicobacter pylori infection is associated with peptic ulcers and gastric cancer in humans. Transmission of H. pylori is still not certain with some epidemiological data suggesting water as a possible transmission route. The objective of this study was to detect H. pylori 16S rRNA gene in five wate r systems in the Mexico City area. Samples were taken between 1997 and 2000 from extraction wells (system 1), from dams used as water sources, both pr e- and post-treatment (systems 2 and 3), treated wastewater (system 4) and non-treated wastewater (system 5). Detection of the H. pylori 16S rRNA gene in water samples was carried out using nested PCR in 139 water samples and confirmed by using cagA gene detection by PCR-hybridisation. The results s howed the presence of H. pylori in 58 (42%) of the water samples in total w ith a prevalence of 68% in system 1, 100% in system 2, 0% in system 3,17% i n system 4 and 20% in system 5. This first stage showed the presence of H. pylori in the tested water systems; nevertheless, viability of the microorg anism in water and vegetables needs to be confirmed as well as demonstratio n of a relationship between human and environmental strains.