New York Food Safety Research Consortium Foodborne Pathogen Database and Molecular Detection and Characterization Core Unit

NON-TECHNICAL SUMMARY: Listeria monocytogenes is a foodborne pathogen that causes an estimated 2,500 human disease cases, including 500 deaths annually. Improved subtyping and characterization methods for this and other foodborne pathogens need to be broadly applied and need to be available to industry and researchers to allow since-based control strategies for foodborne pathogens. This project will develop and apply molecular characterization and epidemiological methods to provide an improved understanding of the transmission of L. monocytogens and other foodborne pathogens. Strain collections, subtyping and characterization methods, and protocols will be made broadly available to facilitate application of the methodologies developed.

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APPROACH: The FSRC program will be administered by faculty and staff in the Department of Food Science at Cornell. They will administer the funds and conduct research as specified and involve faculty at other universities and organizations as formal or informal collaborators. The program will interface with and draw on the existing "Cornell Food and Water Safety Program" (see http://www.foodscience.cornell.edu/fws/fws.htm), which includes more than 30 faculty members at different colleges with research, teaching, and extension efforts and interests in food and water safety. We will use the following specific approaches to accomplish the objectives described above: 1a. Upgrade Pathogen Tracker (i) to allow improved and expanded storage of primary data files, (ii) to allow storage of additional subtype data types (e.g., Multiple-locus variable-nimber tandem repeat [VNTR] analysis; MLVA; single nucleotide polymophism data; microarray data), and (iii) to develop standard operating procedures (SOPs) for different subtyping methods and to link them to Pathogen Tracker data. 1b. Characterize environmental L. monocytogenes isolates using the CDC standard PFGE protocol and include the resulting data in the Pathogen Tracker database. 2. Obtain human, food, and animal isolates from state health departments and other sources. Characterize isolates by automated ribotyping and other molecular subtyping methods. 3. Develop TaqMan primers for detection of single nucleotide polymorphisms and develop MLVA primers and protocols; apply these subtyping methods to selected L. monocytogenes isolates. 4. Characterize selected L. monocytoges isolates, which appear to be characterized by reduced or enhanced virulence (as determined by epidemiological data) by appropriate animal and tissue culture-based virulence assays.

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PROGRESS: 2004/07 TO 2007/06 <BR>
Through this project we have further expanded the PathogenTracker foodborne pathogen subtype database (www.pathogentracker.net) with a particular focus on L. monocytogenes and Salmonella. We have specifically focused our efforts on improving the coverage of Pulse Field Gel Electrophoresis (PFGE) patterns for L. monocytogenes in this database. We have completed PFGE typing using the Centers for Disease Control and Prevention (CDC) standard protocol on more than 400 L. monocytogenes isolates collected from natural and urban environments, farm animals and farm environments, and human cases. We have also performed subtyping by automated EcoRI ribotyping of more than 250 L. monocytogenes isolates from dairy cattle and dairy cattle feed (i.e., silage); these patterns have also been deposited in PathogenTracker and have further enhanced our coverage of animal associated Listeria subtype data. Analysis of these PFGE patterns has revealed the presence of widely distributed and pandemic L. monocytogenes PFGE types, indicating that isolation of the same L. monocytogenes PFGE type in human and a suspected source may have to be interpreted carefully, if the given PFGE type is common and widely distributed (Fugett et al., 2007). In addition, we have added PFGE data for more than 300 Salmonella isolates to the PathogenTracker database and we have continued to generate multilocus sequence typing data for Salmonella, which have also been added to PathogenTracker, further improving the availability of sequence data for design of SNP-based subtyping approaches for foodborne pathogens other than L. monocytogenes. To improve public access to PFGE subtype data we have refined the PathogenTracker WWW interface to provide display of these PFGE patterns similar to that available in the BioNumerics database used by the CDC PulseNet participants. These enhancements will help provide data that can be used in conjunction with human disease associated PFGE subtype data from PulseNet to allow improved tracking of foodborne disease outbreak. To allow for inclusion of isolates from foods and food processing environments, we have also developed specific interfaces for PathogenTracker that will facilitate anonymous isolate submission by the food industry, which will be critical to ultimately allow for improved, including more accurate and more rapid, tracking of human listeriosis outbreak sources. Pathogentracker is also used to provide up-to-date information on characteristics of L. monocytogenes strain collections that are distributed broadly to the worldwide research community, enhancing our ability to compare data across different laboratories. As part of this project, we have also developed and validated new subtyping approaches for L. monocytogenes, including a molecular serotyping approach that combines multiplex PCR and sigB sequence data (Nightingale et al., 2006) as well as an MLVA approach to differentiate and characterize L. monocytogenes isolates with serotype 4b, the most common serotype involved in human listeriosis outbreaks. These improvements will further enhance our abilities to rapidly detect and track human listeriosis outbreaks.
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IMPACT: 2004/07 TO 2007/06<BR>
Salmonella and Listeria monocytogenes cause about 1,050 of the 1,800 human deaths due to known foodborne pathogens that have been estimated to occur annually in the US. The New York Food Safety Research Consortium has expanded and enhanced its collection of publicly accessible L. monocytogenes and Salmonella subtype data to address this food safety issue. This resource will be critical for improved and more accurate tracking and detection of the sources of foodborne disease outbreak and cases. Our efforts to integrate subtype data for isolates from the food industry in our database will be critical in the efforts to integrate efforts by academia, private industry, and state and federal agencies to reduce foodborne illness burdens and their negative economic impact in the US.