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The ovearall goal of this multistate project is to control foodborne pathogens in pre and post harvest environments. The specific objectives defined by the larger project: <OL> <LI> Develop or improve methods for control or elimination of pathogens in pre-and post harvest environments including meat, poultry, seafood, fruits and vegetables and nutmeats. <LI>Develop and validate mathematical modeling to gain understanding of pathogen behavior in macro and micro-environments. </ol> The US has seena dramatic increase in the number of Foodborne illnesses attributed to contaminated produce since the 1970s. The top five produce items, associated with 75% of produce outbreaks, are lettuce and leafy greens, melons, green onions and leafy herbs. Although all of these commodities are produced commercially in Florida, only Florida related tomatoes have been associated with foodborne outbreaks. Due to Florida's climate, many of these products are produced here when they can not be produced in other parts of the US, however the pre-harvest environment and food safety risks associated with it, are significantly different from other locations were produce is grown.
NON-TECHNICAL SUMMARY: An increasing number of gastrointestinal disease outbreaks have been linked to the consumption of fresh fruits and vegetables. The increase in the number of outbreaks caused by produce appears to be related to the increased demand for fresh fruits and vegetables. Between 1990 and 2001, contaminated fresh produce caused 148 outbreaks that account for approximately 9% of all food-borne outbreaks (Smith-DeWaal et al, 2002). Two of the most virulent foodborne pathogens, Salmonella and pathogenic Escherichia coli, have been responsible for many outbreaks associated with fresh fruits and vegetables. Fresh fruits and vegetables are considered high-risk foods because they are minimally processed and are susceptible to contamination at the farm.
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APPROACH: Common procedures will be developed between collaborators during these investigations. When ever possible the Bacteriological Analytical Manual (BAM, http://www.cfsan.fda.gov/~ebam/bam-toc.html) procedures will be used for enumeration and identification of the pathogens in the food products. Relevant equipment includes class II, type A biological safety hoods, microscopes, centrifuges, spiral-plater and scanner, autoclaves and other typical laboratory equipment necessary for these studies. Objective 1. Inoculation of produce: The produce samples will be spot inoculated with a cocktail of 5 E. coli O157:H7 strains and a cocktail of 5 Salmonella strains at different inoculation levels (103 to 106/g). Inoculation will be performed by diluting the respective cocktail mixture approximately 100-fold with sterile water to achieve a 107 CFU/g inoculum level. The produce samples will be spot inoculated with 10 - 100 ul of the inoculum,and allowed to dry for 30 minutes in a biosafety cabinet. A representative sample will be taken to determine the initial pathogen levels for each treatment as described below. To enumerate the E. coli O157:H7 and Salmonella, 10 g samples of each treatment will be homogenized with 90 ml of sterile 0.1% peptone and further 10 fold dilutions will be made using sterile 9 ml 0.1% peptone water blanks. The dilutions will be plated onto selective media. Total plate counts using non selective media, for the produce samples will also be determined to establish if any reduction of the normal sprout microflora occurs due to the various treatments. All experiments will be plated in duplicate for each. For samples that fall below detection limits (10 CFU/g), 25 g samples will then be analyzed for Salmonella using enrichment procedures according to the US FDA Bacteriological Analytical Manual (BAM) procedure. Decontamination Treatments: The response of several foodborne bacteriato UV, ozone, and hydrogen peroxide and other decontamination treatments will be examined. Bacterial foodborne pathogens to be used for the inoculated studies will include pathogenic E. coli strains associated with produce outbreaks and Salmonella spp. strains as described above. As a control for no treatment solution, sterile distilled water will be used at the same volume and treatment time for each produce item.