Foodborne illnesses continue to be a major public health concern.  All members of a particular bacterial genera are often treated by public health and regulatory agencies as being equally pathogenic. However, even within species, virulence factors vary to the point that some isolates may be highly pathogenic, whereas others may rarely, if ever, cause disease in humans.  Hence, many food safety scientists have concluded that a more appropriate characterization of bacterial isolates for public health purposes could be assessing virulence factors.  While individual genetic characteristics of the foodborne pathogen are influential in determining virulence, the ability of these bacteria to induce illness in a human may, also, be greatly affected by numerous host susceptibility factors.  Some of these factors include age of the host, current immune status, type and amount of food consumed, and host cell genetic makeup.  The virulence of particular pathogens may also increase in the presence of certain antibiotics and dietary supplements (e.g., acid neutralizers and high fiber diets). Attempting to establish regulatory guidelines, based on all the above-mentioned factors, is extremely challenging and has led to differences among national regulatory agencies in their standards, such as the U.S. limit for Listeria monocytogenes of 0.04 CFU/g in food versus the European limit of 100 CFU/g in selected cases.  Attempts have also been made to mitigate foodborne pathogen illnesses by means of probiotics, prebiotics, and synbiotics.  This symposium will address these topics to provide a comprehensive treatise of the complex factors that influence the virulence of foodborne pathogens in the human host.

Presentations