Helicobacter pylori and other enteric bacteria in freshwater environments in Mexico City

Background. Helicobacter pylori infection is common in the Mexican populati on; however, sources, routes. and risk factors for infection as well as mod e of transmission remain unclear. Methods. H. pylori was detected by polymerase chain reaction (PCR) techniqu e in three aquatic systems located in the Mexico City area. In addition, mi crobiologic cultures and physicochemical parameters were measured. The syst ems were sampled over an 18-month period (1997-1999), resulting in a total of 212 samples for the different analyses. Results. Twenty-one percent of the samples (16/77) were positive for H. pyl ori; of these, 42% (5/12) were confirmed for cagA gene detection by PCR hyb ridization. Microbiologic samples (n = 74) yielded Aeromonas hydrophila, Ae romonas caviae, Aeromonas veronii, and Vibrio fluvialis. In the samples for physicochemical analyses (n = 61), low concentrations of dissolved oxygen were detected and residual chlorine was less than the inactivation dose, bo th providing conditions for potential survival of H. pylori and other enter ic pathogens in these environments. Conclusions. The results of this study suggest that, in Mexico City, water used for human consumption and irrigation may play an important role as a v ehicle in the transmission of H. pylori as well as infection by other known enteric pathogens. (C) 2001 IMSS. Published by Elsevier Science Inc.