ABSTRACTA high-fat (HF) diet reduces resistance to the foodborne pathogenListeria monocytogenes. We demonstrate that short-term gavage withA. muciniphilaincreases resistance to oral and systemicL. monocytogenesinfection in mice fed a HF diet.A. muciniphilareduced inflammation in the gut and liver of mice fed a high-fat diet prior to infection and reduced inflammatory cell infiltration in the ileum to levels similar to mice fed a low-fat (LF) diet.Akkermansiaadministration had minimal impacts upon the microbiota and microbial metabolites and did not affect individual taxa or impact the Bacteroidetes to Firmicutes ratio. In summary,A. muciniphilaincreased resistance toL. monocytogenesinfection in mice fed a HF diet by moderating immune/physiological effects through specific interaction betweenA. muciniphilaand the host gut.