Screening of Mechanistically Independent Multiple Antimicrobial Treatments for Effective Decontamination of Salmonella on Poultry

NON-TECHNICAL SUMMARY: Illness from Salmonella contaminated poultry remains a huge problem. In the United States, pathogen contamination of foods is responsible for an estimated 76 million cases of food-borne illness and 323,000 hospitalizations at a cost of $7-10 billion annually. Therefore, strategies for effective reduction of pathogen contamination in foods are critical. Complimentary to studies of reduction strategies, investigations into gene regulation during times of stress are necessary in order to better understand the genetic response of food-borne pathogens to their environments and in turn develop more effective and preventative methods for elimination of pathogens in foods. Because poultry processing has been shown to be a major source of Salmonella cross-contamination during processing, reducing the Salmonella contamination level on poultry has become an important focus. Research efforts have concentrated on determining efficacy of methods to decrease Salmonella contamination in the final processing stages. Overall, we hypothesize that the combination of (1) traditional microbiological methods evaluating the potential of antimicrobial treatment strategies to reduce Salmonella contamination on poultry with (2) comprehensive genetic methods to monitor gene expression in response to these treatments can provide a powerful systematic approach to determine which treatments can be combined to achieve the most effective reduction of Salmonella by isolating treatment strategies without producing overlapping stress response systems. <P>APPROACH: In the US, Salmonella-associated food borne illness costs $0.5-2.3 billion in medical expenses and productivity losses each year. Despite application of a variety of antimicrobial interventions, poultry processing continues to be a major source of Salmonella contamination. Consequently reducing contamination levels on poultry products remains a priority for further research. The overall hypothesis of this proposal is that by combining traditional microbiological methods with genomic methods to monitor gene expression antimicrobial mechanisms can be identified that do not stimulate overlapping stress and virulence responses in surviving Salmonella. Using this approach will help to identify the most effective antimicrobials for potential use in multiple hurdle intervention systems. To test this hypothesis by investigating two main objectives: 1. use multiple, disparate antimicrobial treatments to evaluate individually and in combination their effectiveness in reducing Salmonella on chicken breast skins, and 2. perform transcriptome analysis of S. Typhimurium survivors recovered after application of these treatments to determine their genetic responses to these antimicrobials. Microarrays will be utilized to identify the genes that are up- or down-regulated. Results of this study are well-suited for inclusion in USDA risk assessment models since they will identify mechanistically unrelated antimicrobial treatments most likely to not only significantly reduce Salmonella contamination on poultry but are less likely to elicit cross-protective stress or virulence gene responses in survivors.