and Inhibition of by PH3A, Monolaurin, and Grapefruit Seed Extract

infection is the most common cause of gastritis and gastric ulcers. Considering the severe side effects of current antibiotic therapies, it is crucial to find an alternate treatment for infection. In this study, we investigated the anti- effects of a newly isolated strain of (pH3A), monolaurin, grapefruit seed extract (GSE), and their synergies and . Monolaurin and GSE suppressed growth and urease activity at a minimal inhibitory concentration (MIC) of 62.5 ppm. Live cells and cell-free culture supernatant (CFCS) of pH3A with or without pH adjustment also significantly inhibited growth. Although synergy was not observed between monolaurin and GSE, the addition of CFCS significantly enhanced their anti- activities. Moreover, pH3A significantly decreased the ability of to adhere to AGS cells and interleukin (IL)-8 production in the -stimulated AGS cell line. The addition of GSE or monolaurin strengthened these effects. In the study, colonization of the mouse stomach and total serum IgG production were significantly reduced by pH3A treatment, but the addition of monolaurin or GSE did not contribute to these anti- activities. Therefore, the pH3A strain can potentially be applied as an alternative anti- therapy, but evidence of its synergy with monolaurin or GSE is still lacking.