The poloxamer P85 is protective against Listeria monocytogenes invasion

Listeria monocytogenes remains an important foodborne pathogen, and strategies designed to decrease the susceptibility of selected patient populations to foodborne pathogens are therefore desirable. Our objective was to determine if the poloxamer P85 was protective against L. monocytogenes infection. Caco-2 cells were treated with 0.1% (w/v) P85 and challenged with 10(7) L. monocytogenes EGD for 1 hour. A standard gentamicin protection assay was performed to determine invasion differences between the experimental groups. Effects of P85 on the pathogen were studied by measuring bacterial growth and ATP concentrations. In a murine model of listeriosis, FVB mice were administered 150 mg/kg P85 or vehicle control 45 minutes prior to intragastric inoculation of 10(7) L. monocytogenes. Dissemination of the pathogen from the gastrointestinal tract to the liver and spleen was determined 24 hours after bacterial challenge. Pretreatment of Caco-2 cells with P85 significantly decreased L. monocytogenes invasion compared to controls. Repletion of ATP reversed the protective effects of P85. No changes in bacterial ATP or growth profile were detected in P85-treated bacteria. Administration of P85 to mice prior to infection led to decreased dissemination to the liver and spleen compared to vehicle-treated mice. P85 is protective against L. monocytogenes infection when administered prior to bacterial challenge. Modulation of host ATP levels appears to be crucial for the protective effects of P85.