Water-exposed H.pylori presents decreased virulence properties

Abstract

Helicobacter pylori transmission has been associated in epidemiological studies with water. H. pylori has been identified in this environment using molecular techniques. As water may be an environmental reservoir for H. pylori, and because there is lack of information regarding the capacity of water-exposed bacteria to induce a response in host cells, we assessed the cultivability of water-exposed H. pylori and determined whether these bacteria retain the ability to adhere to and to induce inflammation. We used H. pylori strain 26,695 and AGS cell line. Bacteria were grown in TSA with 5% sheep blood and incubated for 48 hours at 37 °C under a microaerophilic atmosphere. After that, H. pylori was exposed to water at 25 °C, in aerobic conditions for different time periods. H. pylori cultivability was determined by standard plating methods. Adhesion to and Interleukin-8 production by AGS cells were assessed by ELISA, using an anti-H. pylori antibody and a commercially available kit, respectively. Our results showed that, after 24 hours water exposure, H. pylori was no longer cultivable. Water exposure of H. pylori led to a significant decrease of its ability to adhere to AGS cells. Also, significantly lower IL-8 secretion was observed in AGS cells cultured with water-exposed H. pylori than with unexposed bacteria. Altogether, these results suggest that after being exposed to water, planktonic H. pylori presents decreased virulence properties. As such, additional mechanisms of protection in water, such as inclusion in biofilms, might be needed for the maintenance of the infectious ability by this bacterium.