Enhancement for the Safety of Pork Products

NON-TECHNICAL SUMMARY: Pork and pork products may contain naturally occurring organisms or substances which may be of significance to human health. This project researches the available means to avoid, eliminate or reduce to acceptable levels the organisms or substances which may be of significance to human health in live pigs, pork and pork products.

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APPROACH: The Food Safety Consortium has actively applied its research by assisting the food industry with specific problems as well as helping the meat industry convert to HACCP based inspection. Iowa State University plays a major role in the Food Safety Consortium. Collaborators from the University, the National Animal Disease Center, the National Veterinary Services Laboratories and industry have worked together to enhance the safety of pork products. These projects include animal production techniques, processing and distribution, as well as consumer issues (both domestic and foreign) related to the safety of pork and pork products. Other programs which interact with the Consortium, but which are separately funded, include the World Health Organization Collaborating Center and the NASA Center for the development of food supplies for long term space missions. Iowa State University is also uniquely positioned to help the food industry and consumers in regard to food irradiation. The Linear Accelerator Facility is the only food irradiation facility of its size at a Land Grant University, and offers both individual research opportunities as well as training courses for interested companies or individuals. With the USDA regulations of the use of irradiation for red meats, the Linear Accelerator Facility takes on an even more important role as it interacts with the Food Safety Consortium.

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PROGRESS: 2006/08 TO 2008/08<BR>
OUTPUTS: The Iowa State University component of the Food Safety Consortium funded five research projects and two diversity graduate assistantships in 2007-2008. The primary basis for research under this research program has been the enhancement of the safety of pork and pork products. Since the Food Safety Consortium was not funded by special grants during this time period, the funding to continue the program was made available from HATCH funds and other administrative funds within Iowa State University. Diversity Graduate Assistantships: Recognizing the need to enhance diversity in the field of food safety, the Iowa State University portion of the Food Safety Consortium funded two diversity assistantships in 2007 - 2008. The Food Safety Consortium funded two research project relating to preharvest interventions. The first evaluated the immune response of swine to salmonellae, to determine if there are opportunities to prevent contamination of the live animal. They have identified a large number of genes that are differentially expressed in whole blood at 48 hours post salmonella infection between pigs that persistently shed bacteria up to 21 days post infection and those that shed low to non-detectable numbers. Dr. Cornick investigated the potential for Escherichia coli O157:H7 to become endemic in swine. Her research showed that fewer pigs fed diets containing subtherapeutic levels of either tylosin or chlorotetracycline shed E. coli O157:H7 for longer than 2 weeks compared to those fed an antibiotic-free diet. These results suggest that subtherapeutic antibiotics may reduce the persistence of E. coli O157:H7 in swine. Macrolides are an important class of antibiotics used for clinical treatment of campylobacteriosis caused by Campylobater spp. There is a trend that Campylobacter, especially C. coli, is increasingly resistant to macrolides. We also found that the field isolates collected from swine and turkey farms harbored different types of resistance-associated mutations compared with in vitro selected erythromycin-resistant mutants. The Food Safety Consortium funded two post-harvest research projects, one on decontamination and the other on detection methods. Dr. Mendonca's laboratory researched the destruction of Salmonella enterica on pork Skin using a solution of organic acids and surfactants. Dr. Brehm-Stecher's laboratory evaluated flow cytometry as a detection method for foodborne pathogens in pork. Both pathogens were directly detectable at high levels of contamination (106 CFU/g) in cubed pork (Salmonella) and pork franks (Listeria). Unambiguous detection of both pathogens at low levels (102 CFU/g) was also possible after only 8 hours of non-selective preenrichment in either buffered peptone water or universal preenrichment broth. It is imperative that the information developed in the research laboratory be transferred to the general public, in a format which is accessible to them. The Consortium continues to help fund the Food Safety web page. <BR><BR>
IMPACT: 2006/08 TO 2008/08<BR>
1) Contaminated foods or liquid dilutions made from such foods may contain high loads of particulate matter or non-target microflora, both of which could present challenges to the direct detection of target cells. Flow cytometry is a detection technology that allows the rapid analysis of complex microbial populations according to single cell light scatter and fluorescence characteristics. Research funded by the Food Safety Consortium (FSC) has resulted in the refinement of methods to increase detection sensitivities for direct detection of both pathogens in pork meats were as low as 105 CFU/ml. Enumeration with flow cytometery has been shown to be equivalent to tradition methods, but with the results available several hours or days earlier than traditional methods.<BR> 2) Campylobacter species including Campylobacter jejuni and Campylobacter coli are the most commonly recognized bacterial causes of foodborne illnesses. Campylobacter is commonly present in farm animals including pigs, chickens, turkeys, cattle and sheep. Recently, C. jejuni and C. coli have become increasingly resistant to antimicrobials, this is considered an emerging public health problem. C. coli isolates from swine and turkeys show much higher resistance rates to macrolides than Campylobacter strains from other animals. Campylobacter resistance to macrolides is still poorly understood. Novel methods are urgently needed for rapid detection of the antimicrobial resistance in Campylobacter to facilitate clinical treatment of campylobacteriosis. Research funded by the FSC has identified previously unrecognized mechanisms for macrolide resistance in Campylobacter. Field isolates collected from farms and the in vitro selected mutants had different types of target mutations. These observations provide new insights into the development of macrolide resistance in Campylobacter.<BR> 3) In the past few years there have been several reports linking swine and /or pork products to outbreaks of human disease caused by E. coli O157:H7. Previously research has shown that E. coli O157:H7 can establish and maintain a population in the intestinal tract of some market-weight pigs for at least 2 months. This time period is similar to that which occurs in experimentally inoculated ruminants and suggests that there is not an absolute biological barrier to the colonization of swine by E. coli O157:H7. These results suggest that subtherapeutic levels of antibiotics may reduce the duration of shedding of E. coli O157:H7 by swine. <BR>4) Recognizing the need to enhance diversity in the field of food safety, the Iowa State University portion of the FSC funded two diversity assistantships in 2007-2008. The FSC consumer web-site project continues to receive a significant number of site visits. More than 600,000 visitors have accessed the food safety web site home page or one of its links over the past year. Visitors accessed the site with an average of approximately 10 minutes per visit. While it is difficult to accurately assess consumer education from this information, it is clear that the web site is reaching a broad spectrum of the general public.