Synergistic Effect of Eugenol and Probiotic Lactobacillus Plantarum Zs2058 Against Salmonella Infection in C57bl/6 Mice.

Previously, we showed the preventive effects ofLactobacillus plantarumZS2058 (ZS2058) onSalmonellainfection in murine models. In this work, we found that eugenol has a selective antibacterial effect, which inhibitedSalmonellamore than probiotics ZS2058 in vitro. It suggested a synergistic effect of them beyond their individual anti-Salmonellaactivity. We verified the conjecture in murine models. The results showed that the combination of ZS2058 and eugenol (CLPZE) significantly increased (p= 0.026) the survival rate ofSalmonella-infected mice from 60% to 80% and the effect of CLPZE on preventingSalmonella-infection was 2-fold that of ZS2058 alone and 6-fold that of eugenol alone. CLPZE had a synergistic effect on inhibiting ST growth (the coefficient drug interaction ((CDI) = 0.829), reducing its invasiveness (CDI = 0.373) and downregulating virulence genes' expression in vitro. CLPZE helped the host form a healthier gut ecosystem. CLPZE also elicited a stronger and earlier immune response to systemic infection. In conclusion, these obtained results suggest that ZS2058 and eugenol have a synergistic effect on preventingSalmonellainfection and open new perspectives in the strategies of controlling the prevalence ofSalmonellaby combination of probiotics and functional food components.