Cinnamomum cassia and Syzygium aromaticum Essential Oils Reduce the Colonization of Salmonella Typhimurium in an In Vivo Infection Model Using Caenorhabditis elegans

The regulation of intestinal colonization in livestock by means of non-bactericidal additives is an important management lever for zoonotic bacteria such as Salmonella spp. Caenorhabditis elegans is proposed here as a model for the evaluation of five essential oils (EOs) as anti-colonization products against Salmonella Typhimurium. An evaluation of the toxicity of EOs for C. elegans showed LD50 values ranging from 74.5 +/- 9.6 mu g/mL for Cinnamomum cassia (CEO) to 271.6 +/- 14.9 mu g/mL for Syzygium aromaticum (SyEO). Both EOs significantly inhibited bacterial colonization in the digestive tract of C. elegans with reductions of 0.88 and 0.70 log CFU/nematode at nontoxic concentrations of 50 mu g/mL and 150 mu g/mL, respectively. With the minimal bactericidal concentrations of CEO and SyEO against S. Typhimurium being 312.5 mu g/mL and 625 mu g/mL, respectively, an antibacterial effect can be excluded to explain the inhibition of the bacterial load. The anti-colonizing activity of these two EOs could, however, be related to an inhibition of the swimming motility, which was significantly reduced by 23.47% for CEO at 50 mu g/mL and 19.56% for SyEO at 150 mu g/mL. This study shows the potential of C. elegans as a predictive in vivo model of anti-colonizing activities that is suitable for the evaluation of essential oils.

Automated summary

Regulating intestinal colonization in livestock by non-bactericidal additives is crucial for managing zoonotic bacteria like Salmonella spp. Caenorhabditis elegans is proposed as a model for evaluating the anti-colonization effects of essential oils, with both Cinnamomum cassia (CEO) and Syzygium aromaticum (SyEO) significantly inhibiting bacterial colonization in the nematode's digestive tract. This inhibition may be related to reduced swimming motility rather than direct antibacterial effects.