Ethanol ingestion increases susceptibility of mice to Listeria monocytogenes

Excessive consumption of alcohol is associated with an increase in the frequency and severity of infectious diseases. Ethanol adversely affects specific and nonspecific aspects of the immune response. We used a murine model to determine whether ethanol ingestion impairs host mechanisms of resistance to Listeria monocytogenes. Naive mice and mice immune to L. monocytogenes were pair-fed either a Leiber-DeCarli liquid diet containing 7% (v/v) ethanol or an isocaloric control diet for 7 days. Then, nonimmune mice were given a sublethal dose of L. monocytogenes and studied 2 and 5 days after infection, and immune mice were challenged with a lethal dose of L. monocytogenes and studied 5 days after infection. Multifocal liver abscesses developed in nonimmune ethanol-treated and control mice 2 days after infection. Bacterial colony counts in the spleens were similar between the two groups; however, counts in the livers were slightly higher in ethanol-treated mice as compared with those in control mice. Five days after infection the nonimmune ethanol-treated mice had large necrotizing liver granulomas and organ bacterial colony counts 100 to 1000 times higher than those in control mice. Immune ethanol-treated mice had large areas of liver necrosis and inflammation containing numerous Gram-positive bacilli, whereas immune control mice had small, well-formed granulomas and much less necrosis. Organ bacterial colony counts were about 100 times higher in immune ethanol-treated mice as compared with those in immune control mice. Liver enzyme levels and mortality were significantly higher in ethanol-treated immune and nonimmune mice as compared with those in immune and nonimmune control mice. Data support the suggestion that ethanol consumption impairs the development and expression of T cell-mediated immunity of mice to L. monocytogenes, resulting in increased susceptibility to infection with this organism.