Interactions Between Foodborne Bacterial Pathogens and the Microbiome

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Most foodborne bacterial pathogens originate in the gastrointestinal tract of food-producing animals and contaminate food-products during production, processing, or distribution. If the overall abundance of bacterial pathogens was reduced on the farm it would result in a decrease in the burden of foodborne illness. In the gastrointestinal tract of food-producing animals, bacterial pathogens interact with resident non-pathogenic bacteria, hereafter referred to as the microbiome. In a healthy animal, the gastrointestinal microbiome is composed of a diverse and dynamic bacterial population. Competition for resources in this environment is fierce. In the last year, several enteric bacterial pathogens have been shown to contain a range of systems that are responsible for killing members of the microbiome in the gastrointestinal tract. These systems offer a competitive advantage to bacterial pathogens since killing competitors increases the availability of space and nutrients to support their own growth and proliferation. The ability to antagonize the gastrointestinal microbiome appears to be an important virulence factor for some pathogens, but this is far from being understood. At the molecular level, very little is known about the details of the interactions between bacterial pathogens and the microbiome. The focus of my research program is expanding the fundamental knowledge of the interactions that occur between bacterial pathogens and the microbiome of food-producing animals. A more thorough understanding of pathogen/microbiome interactions will contribute to improving food safety in several ways. Elucidating the mechanisms that bacterial pathogens use to antagonize the microbiome and understanding the role of these mechanisms in virulence will contribute to more accurate risk assessments. The composition of the gastrointestinal microbiome, in other words which bacterial species are present and in what abundance, can vary widely between individual hosts and over time. Some bacterial species in the microbiome appear to have genetic traits that allow them to resist killing by bacterial pathogens, and some appear to have the ability to launch a counter attack that is fatal for the pathogen. Thus, the microbiome composition may have a role in determining if the pathogen will be successful in establishing an infection. Characterizing and ultimately manipulating pathogen/microbiome interactions may offer novel pathogen exclusion strategies while reducing the requirement to use therapeutic agricultural antibiotics. By increasing the fundamental knowledge of the interactions that occur between bacterial pathogens and the microbiome, my research program will broaden the understanding of bacterial pathogen virulence traits, generate novel pathogen reduction strategies for use in agriculture, and contribute to decreasing the burden of foodborne illness.