Strain-specific inhibition of Helicobacter pylori by Lactobacillus salivarius and other lactobacilli

Objectives: To investigate the anti- Helicobacter pylori activity of 28 strains of Lactobacillus salivarius and 12 other lactobacilli, isolated from different sites and from different geographical regions. Methods: An in vitro agar plate diffusion assay was employed to assess the Lactobacillus anti- H. pylori activity. Results: Nine out of 28 L. salivarius strains and 3/12 other Lactobacillus species tested inhibited H. pylori growth. There was no correlation between ecological niche/geographical location of isolation of the lactobacilli and their inhibitory capability. Further studies on strain L. salivarius UCC119 showed that this strain could inhibit growth of 6/6 clinical isolates of H. pylori, five of which were antibiotic-resistant. This inhibition was not due to acid production and was not mediated by a protein, but did require the presence of live cells. Conclusions: Growth inhibition of H. pylori by L. salivarius is strain-dependent and is not linked to any particular environmental niche or geographic location. Strains of L. salivarius showing highest anti- H. pylori activity may be useful as an adjunct in the treatment of strains that are resistant to conventional antibiotics.