Resistance of Salmonella Enteritidis to the Antimicrobial Stress of Egg Albumen

In the US, 1 in 20,000 eggs is reported to be contaminated with one type of Salmonella bacterium called Salmonella enteritidis (SE). Each year,the US table egg industry produces more than 67 billion eggs, and hence, more than 3 million eggs may be contaminated. Thus, SE has become one of the major causes of human foodborne illnesses in the US, and is the most common cause of foodborne disease associated with eggs. Why eggs become contaminated with SE more frequently than with other commontypes of Salmonella, such as Salmonella typhimurium (ST) is not known. Egg albumen contains natural substances that can kill bacteria. The investigators' preliminary studies indicate that SE isolates from humans remain alive in chicken albumen significantly longer than ST. They want to identify the genes of SE responsible for this relative resistance to eggs. They have identified possible candidates and now wish to study how they mediate resistance. In this project, the investigators will 1) characterize the SE factors responsible for egg white resistance and 2) develop new "fingerprinting" methods to determine if certain clinical isolates of SE are more likely than others to exhibit egg albumen resistance. Improving our understanding of how SE resists egg albumen will allow for the development of a vaccine to prevent SE infection in chickens, and interrupt transmission to humans. These two lines of investigation will contribute to the goals of Egg Safety Action proposed by FDA and USDA to eliminate egg-associated SE illness by Year 2010.