Development of Rapid Detection Methods and Novel Control Measures for Salmonella in Poultry

This dissertation consists of three research parts: 1) development of rapid detection methods for foodborne pathogens; 2) immune response of chicken cells against Salmonella and bacteriophage P22; 3) evaluation of novel control measures for poultry productions. In order to develop rapid and accurate detection methods for foodborne pathogens, two types of PCR assays were utilized. Three foodborne pathogens included Campylobacter, Escherichia coli and Salmonella in watershed were qualitatively and quantitatively detected by multiplex PCR and qPCR (chapter 2). Since Salmonella species are commonly present in poultry and poultry products as well as most popular foodborne pathogen in the United States, we have developed multiplex PCR for simultaneous detection of Salmonella genus, Salmonella subspecies I, S. Enteritidis, S. Heidelberg, and S. Typhimurium. In addition, low numbers of Salmonella were quantified via qPCR (chapter 3). To evaluate the immune responses in chicken macrophage cells against Salmonella and bacteriophage P22 invasion, cell culture models were utilized. The productions of cytokines such as IL-4, IL-8, IL-10, and IFN-ã were measured by ELISA and qRT-PCR (chapter 4). Prebiotics is a non-digestible food component that provides beneficial effects on the host by stimulating the growth and activity of selected bacteria in the lower intestinal tract. In this study, we evaluated a production performance in pasture flock raised broilers after treatment with three different prebiotics. Furthermore, microarray was conducted to evaluate different gene expressions according to prebiotics treatments using small intestinal cells and ingenuity pathway analysis (IPA) software was used to analyze functional networks among up- or down-regulated genes based on microarray data (chapter 5). Lastly, DGGE was performed to evaluate gastrointestinal microflora shifts in pasture flock raised chickens supplemented with prebiotics (chapter 6)