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The aim of this project is to develop comprehensive data sets on foodborne pathogen subtypes isolated from foods, humans, animals, and environmental sources and to understand the transmission of foodborne pathogens from farm-to-table. <P>
Specifically, we will accomplish the following objectives:
<OL> <LI> Characterize food, human, animal, and environmental Listeria monocytogenes and Salmonella isolates by DNA fingerprinting methods to define Salmonella and L. monocytogenes subsets that differ in their abilities to cause human foodborne disease. <LI> Characterize L. monocytogenes isolates by tissue culture pathogenicity assays to define the virulence characteristics of L. monocytogenes associated with different sources. <LI> Characterize Salmonella isolates for antibiotic resistance phenotypes and genotypes. <LI> Perform field studies to understand and control L. monocytogenes transmission at processing, to define, develop, and communicate the most effective (cost vs. risk reduction) L. monocytogenes control strategies for RTE meat and poultry processors; <LI> Perform field studies to understand and control L. monocytogenes transmission at foodservice and retail, where the overall goal is to define, develop, and communicate the most effective L. monocytogenes risk reduction strategies for RTE meat and poultry at retail/foodservice; <LI> Perform studies to understand and control L. monocytogenes transmission at the consumer level, where the overall goal is to define, develop, and communicate the most effective and applicable L. monocytogenes risk reduction strategies at this level of the food chain; <LI> Perform food systems analysis, where the overall goal is to develop a mathematical model of L. monocytogenes transmission from RTE processing plants to consumers in order to allow improved prediction of effective intervention strategies with regard to overall risk reduction; <LI> Study economics of L. monocytogenes control strategies throughout the RTE meat and poultry food system, where the overall goal is to develop a comprehensive analysis of the costs and feasibility of selected L. monocytogenes control alternatives; <LI> To train students with expertise in Listeria control strategies from processing plant to consumer.
NON-TECHNICAL SUMMARY: Transmission of foodborne pathogens represents a complex system involving animals, environmental sources, and humans. Salmonella and Listeria monocytogenes represent the two human foodborne pathogens that cause the most foodborne disease associated deaths in the US. This project uses molecular subtyping methods in conjunction with mathematical modelling, evolutionary and population genetics analyses to better understand the transmission of Salmonella and Listeria monocytogenes. The goal of this study is to develop improved control strategies for these foodborne diseases. Studies completed and published during this reporting period have provided a variety of important new findings on the transmission of Listeria monocytogenes that will provide avenues for improved detection and control of this pathogen. In particular, our results indicate the potential importance of cattle farms as reservoirs for L. monocytogenes that have the ability to cause human disease. Research studies on the molecular basis of reduced ability to cause human disease have also provided us with the specific knowledge needed to develop methods to specifically detect those L. monocytogenes subtypes most likely to cause human disease, reducing the negative economic impact associated with current approaches that classify some L. monocytogenes as public health hazard even though they may lack the ability to cause human disease.
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APPROACH: <BR>
(1) Listeria monocytogenes and Salmonella isolates will be obtained through various collaborations with the New York State Animal Health Diagnostic Laboratory, New York State Department of Health, and the New York State Department of Agriculture and Markets. Isolates will be characterized by different DNA fingerprinting methods (including automated ribotyping, multilocus sequence typing, and pulsed field gel electrophoresis typing) if subtyping has not yet been completed through other parallel projects or by collaborators. <BR> (2) Tissue culture pathogenicity assays will be used to characterize L. monocytogenes isolates in order to determine correlations between molecular subtype data and virulence characteristics. <BR> (3) Salmonella isolates for antibiotic resistance phenotypes and genotypes using PCR-based and DNA sequencing methods. Evolutionary and population genetics analyses will be performed to better understand the spread and distribution of antibiotic resistant Salmonella. <BR> (4) A comprehensive review of the literature on Listeria monocytogenes transmission will be conducted to update existing reviews as well as the FDA/USDA risk assessment at the time of initiation of the project; <BR> (5) An industry survey will be conducted to determine current concerns, issues, practices, vulnerabilities and needs for Listeria control.<BR> (6) A foodservice and retail industry survey will be conducted to determine current concerns, issues, practices, vulnerabilities and needs for Listeria control. <BR> (7) An extension outreach survey will be conducted on current state of knowledge and practices of health care providers in advising those at risk of listeriosis. <BR> (8) A conference will be organized to bring together interested stakeholders from the public health, academic, industry, and regulatory sectors to discuss the issues and to develop a best approach to address the objectives.<BR> (9) Standard detection and subtyping methods for L. monocytogenes and Listeria spp. will be used to test environmental and product samples from at least six processing establishments and 8-10 retail operations. Data will be used to analyze contamination patterns, to determine sources/spread and persistence of L. monocytogenes and Listeria spp., and to develop mathematical transmission models. <BR> (10) Outreach activities, through workshops and WWW-based training materials, will be conducted focusing on training and communication of existing and new knowledge on the most effective L. monocytogenes risk reduction strategies to processors, retail and deli operators, and managers, and health inspectors.