Helicobacter pylori is killed by nitrite under acidic conditions

Background-Due to the expression of Helicobacter pylori is able to itself in the human stomach conditions. A novel host was recently proposed, suggesting that the formation of salivary nitrite in symbiosis with facultative anaerobic bacteria in the oropharynx, is aimed at enhancing the antimicrobial activity of gastric juice. Aims-To investigate whether the addition of nitrite in physiological concentrations influences the resistance of H pylori to acid. Methods-H pylori cultured from fresh gastric biopsy specimens was exposed for 30 minutes to normal saline and to HC1/KC1 buffer (0.2M) at pH 2 with urea (5 mM) added. The influence of potassium nitrite (50-1000 mu mol/l) on bacterial survival was determined. Results-Addition of nitrite (1 mM) to acidic solutions (pH 2) resulted in complete kill of H pylori within 30 minutes exposure time whereas acid alone allowed the organism to survive (p<0.001). The antimicrobial effect of nitrite at pH 2 against H pylori was dose dependent and complete kill of organisms occurred at concentrations greater than or equal to 500 mu mol/l. Conclusion-Acidified nitrite has and bacterial activity against H pylori. This should prompt further research into the effect of salivary nitrite on the survival of H pylori in the human stomach.