#05-063

Complete

Date Full Report Received

07/12/2006

Date Abstract Report Received

07/21/2008

Investigation

Institution: , ,
Primary Investigator:

The development and testing of molecular epidemiological tools for pre-harvest food safety applications is an important and rapidly evolving issue. This means that it is vital to track bacterial contamination of our food to its source, whether that contamination originated during production, transport, holding/lairage or even within processing plants, delivery, stores, or at home. As an example Salmonella contamination found in meat products could be tracked back to a failed water supply on a farm if a successful molecular tracking method could be developed. By identifying sources we can prevent further contamination of our food originating from that source. As part of this project our goal was to take steps toward the development of improved molecular epidemiology tools using new whole genome informatics. Specifically our goals were: 1) To sequence ten (10) identified heterogeneous target regions (at least 3x coverage) from 40 Salmonella enterica serotypes 2) Develop specific PCR primers that will amplify these target regions in all serotypes.3) Test the targets for their ability to sensitively and specifically identify or distinguish isolates of S. enterica from our culture collection. We successfully completed all of these objectives and exceeded the goals by including an additional 10 serotypes in the sequencing objective. We have developed a set of primers that are able to amplify target regions in all of the serotypes we have tested. We have also sequenced a set of test isolates that have allowed evaluation of a computer database genetic homology comparison method using the data generated in this study. Our results show that we can identify the S. enterica serotypes test isolates correctly, which is a valuable tool in itself. With the increase cost of serotyping a genotyping method would be extremely valuable to the industry. We are now using a neural network approach to develop a model that will allow evaluation of complicated set of data that is generated during the homology comparison step in this process. Thus, we have developed a method that shows great potential as a genotyping method for S. enterica serovars and has potential as a method for source tracking if it becomes possible to continue to expand and improve the genetic databases and models we have initiated. For more information contact Dr. Scot E. Dowd Ph.D. USDA-ARS-LIRU 1604 E. FM 1294 Lubbock, TX 79403. 806-746-5356. sdowd@lbk.ars.usda.gov