1a. Objectives (from AD-416):
1. Using population genetics, track bacterial migration and adaptation of foodborne pathogens through poultry processing and the associated environment. Evaluate the variations and influence of genetic and strain diversity from animal through the processing plant. 2. Examine the role of protozoa and other potential biological populations in the microbial ecology of foodborne pathogens through poultry processing. 3. Evaluate the potential for protozoa and other biological controls to be used as intervention or mitigation strategies for human pathogens in poultry processing and processing facilities. 4. Based on objectives 1-3, develop and evaluate physical and chemical intervention strategies to reduce contamination by foodborne pathogens of poultry products.
1b. Approach (from AD-416):
The focus of this research would be called the “transmission phase” by epidemiologists or the “migration phase” by ecologists. Processing of poultry products creates many severe barriers to transmission such that most of the pathogens are lost. However, it is clear that the barriers are incomplete and enough pathogens survive and pass to human consumers to cause foodborne disease. It is reasonable to assume that bacteria have adaptive strategies that improve the chances that some clones will survive processing making transmission to humans possible. The objectives of this project are designed to determine the relative ability of genetically different clones of foodborne pathogens to survive barriers that are encountered in the poultry processing plant. This will be followed by studying specific biological barriers that are common to ecosystems and are often responsible for limiting migration of bacteria. It is also likely that protozoa will be found in the processing environment that are not only ineffective in killing pathogens but may even be protective. Therefore, we plan to study the mechanisms of destruction or protection as they are uncovered. The knowledge that is gained from these studies will be used to design enhanced barriers in an attempt to improve the microbiological benefits of poultry processing.
3. Progress Report:
ARS scientists completed a study on an intervention strategy to kill Listeria on raw poultry meat exposed to airborne cells. Using a previously developed germicidal ultra-violet light method, we treated breast fillets with the low numbers expected to be present due to cross contamination from drain spray. Data show that treatment at 800 micro-Watts/cm2 for times as short as 5 seconds is adequate to significantly reduce numbers of L. monocytogenes on raw chicken breasts. This type of intervention could be applied to cut up parts in the slaughter plant and has potential to break the cycle of Listeria contamination from slaughter plant to cooking plant with the transfer of raw product. This data has been collected, analyzed and the resultant paper is currently under review at an international journal. ARS scientists completed a study on a proprietary broiler chill water additive designed to maintain the efficacy of chlorine as an antimicrobial even in the presence of organic matter (such as broiler carcasses). This compound was found to limit the number of total aerobic bacteria on carcasses and lessen the amount of cross contamination with Salmonella and Campylobacter. Work was conducted both on a bench scale level and in a pilot plant with whole broiler carcasses. These data have been collected and analyzed, the resultant manuscripts are currently in preparation. ARS scientists completed a study to determine the best means to sample broiler skin for the recovery of food-borne pathogens, Salmonella and Campylobacter. Carcasses were inoculated with known numbers of both pathogens and breast skin was sampled by a non-destructive sponge method and by a skin excision method. These data have been collected and are currently being analyzed prior to preparation of a manuscript. In collaboration with ARS scientists from Clay Center, NE, the genome of a Urease Positive Campylobacter lari was fully sequenced. Preliminary annotation of the sequence shows a unique gene set but analyses has not been completed to show if there is sharing of genes between this population of bacteria and Campylobacter that commonly contaminate poultry products. In collaboration with a scientist in Denmark, total genome sequences for 42 isolates of Listeria monocytogenes have been analyzed to find which genes are evolving jointly. Preliminary analysis indicates that the genes are not as linked as expected; that is to say, there appears to be extensive trading of genetic material between different lineages. Such trading of genes means that the organism is more adaptive than expected and more information is needed to fully trace lineages of the organism.
Meinersmann, R.J., Berrang, M.E., Little, E. 2013. Campylobacter spp. recovered from the Upper Oconee River Watershed, Georgia, in a four-year study. Microbial Ecology. 65(1):22-27.