2006 Annual Report
This research specifically applies to Objective 2.2 Production and Processing Ecology in the National Program 108 (Food Safety) by providing new knowledge to reduce pathogens for a safe, wholesome product and addresses the following specific goals:
18.104.22.168 Determine: sources of contamination on animals, seafood and produce and their effect on microbial load; the relationship of incoming microbial load on microbial load of the final products; and effect of feed withdrawal on microbial load. 22.214.171.124 Determine effect of microorganisms within the processing ecosystem on the microbial status of the final product. Identify which areas of the processing plant lead to a significant increase in pathogens on the product. Delineate mechanisms of pathogen transmission, and the effect of processing systems and management. 126.96.36.199 Trace sources (niches) of pathogens in processing ecosystems. Determine the physiological status of microorganisms within these niches, and determine any special characteristics required for survival. Determine role of quorum sensing and nutrient availability. Identify conditions where pathogen growth is restricted.
The presence of bacteria that cause foodborne illness needs to be lowered on processed poultry so that the final consumer will stand less of a chance of becoming ill as a consequence of handling or eating poultry products. Achievement of the project goals will promote public health and create opportunities for marketing safer poultry products domestically and abroad.
Year 2 (FY ’07 – 08) 1. Determine the role that outside environmental sources of Listeria monocytogenes play in the presence of this pathogen in poultry further processing facilities: begin to collect isolates from plants and surrounding environments. 2. Develop and test intervention strategies to eliminate L. monocytogenes and Campylobacter from meat products or processing plant surfaces: test possible means to physically plug the vent, begin testing ultraviolet light and food grade chemicals on numbers of L. monocytogenes on raw product. 3. Evaluate gene expression profiles of L. monocytogenes and C. jejuni in conditions relevant to poultry processing environments: compare expression in biofilms versus planktonic L. monocytogenes cells. 4. Evaluate the influence of animal agriculture on Campylobacter in the environment: examine gene expression profiles of Campylobacter detected in various areas of the plant under various conditions.
Year 3 (FY ’08 – 09) 1. Develop and test intervention strategies to eliminate L. monocytogenes and Campylobacter from meat products or processing plant surfaces: measure effect on the resistance of experimental isolates to therapeutic antimicrobial drugs and meat quality. 2. Evaluate gene expression profiles of L. monocytogenes and C. jejuni in conditions relevant to poultry processing environments: study knockout mutants of genes related to biofilm development in L. monocytogenes.
Year 4 (FY ’09 – 10) 1. Determine the role that outside environmental sources of Listeria monocytogenes play in the presence of this pathogen in poultry further processing facilities: finish collection of L. monocytogenes isolates. 2. Develop and test intervention strategies to eliminate L. monocytogenes and Campylobacter from meat products or processing plant surfaces: develop method to create L. monocytogenes biofilms in drain pipes. 3. Evaluate gene expression profiles of L. monocytogenes and C. jejuni in conditions relevant to poultry processing environments: develop methods for synchronized growth of Campylobacter 4. Evaluate the influence of animal agriculture on Campylobacter in the environment: determine gene expression of Campylobacter under condition common to the poultry processing environment
Year 5 (FY ’10 – 11) 1. Determine the role that outside environmental sources of Listeria monocytogenes play in the presence of this pathogen in poultry further processing facilities: characterize isolates collected and make comparisons. 2. Develop and test intervention strategies to eliminate L. monocytogenes and Campylobacter from meat products or processing plant surfaces: test treatments to lower the numbers of L. monocytogenes associated with biofilms in drains. 3. Evaluate gene expression profiles of L. monocytogenes and C. jejuni in conditions relevant to poultry processing environments: compare expression of Campylobacter cells in different stages of cell cycle. 4. Evaluate the influence of animal agriculture on Campylobacter in the environment: collect and characterize Campylobacter isolates from environmental sites.
Process control in broiler slaughter plants – Campylobacter prevalence: Measuring process control in commercial broiler slaughter plants has traditionally meant counting the number of carcasses positive for Salmonella. However, legal challenges to this system have left the regulatory agency (FSIS) in need of another method to monitor processors to assure that their process is in control. We completed the sample collection phase of a large collaborative effort with FSIS and Stan Bailey (ARS) to test the use of E. coli counts as a measure of process control in broiler slaughter and processing. Our earlier findings show that E. coli counts tend to go down during processing roughly parallel to the number of Campylobacter. Four replications were conducted each with 20 processing plants; carcasses sampled at re-hang and post chill. About 3,200 Campylobacter isolates were collected and preserved for future study. Campylobacter prevalence and number data is now being analyzed. These data will provide the poultry industry and interested researchers with a very good idea of what numbers of Campylobacter are entering plants with the live birds. Furthermore, the counts on fully processed broiler carcasses will illustrate the level of reduction that is being achieved due to current processing methods. Further analyses of isolates are being performed to discover if there is selective survival of Campylobacter subtypes. (National Program Component 1, Problem Statement 1.1.2 Epidemiology and 1.1.3: Ecology, Host Pathogen and Chemical Contaminants Relationships)
Effect of subtherapeutic administration of antimicrobial (tylosin) on Campylobacter numbers on broiler carcasses during processing: Antimicrobials may be added to broiler feed in subtherapeutic doses as a growth promoter. It s not clear how this practice may affect the numbers or antimicrobial resistance profile of Campylobacter on processed carcasses. We planned and conducted a study to determine the effect of sub-therapeutic application of antimicrobial (tylosin) on the numbers of Campylobacter on broiler carcasses during processing. We also measured the antimicrobial resistance of Campylobacter isolates that remained on broiler carcasses during processing. Broiler chickens were raised with or without tylosin in the diet. All birds were intentionally colonized with C. jejuni. At 42 d, broilers were processed in the pilot plant using commercial style equipment. Campylobacter counts were measured at several points during processing. Isolates were collected and characterized relative to antimicrobial resistance. The relationship between feed and the characteristics of bacteria found on processed carcasses is new information that will help companies understand the consequences of subtherapeutic antimicrobial feeding regimens. This information will be useful to the poultry industry as they plan feed formulations.
Antimicrobial resistance of salmonellae from retail chicken: The level of antimicrobial resistance on salmonellae from US retail chicken is not readily available in the literature. We completed a survey study whereby the antimicrobial resistance profile of a collection of salmonellae isolates originally recovered from retail chicken was determined. These data are important to the industry, regulators and consumers, all of which are concerned with the possibility of antimicrobial resistant salmonellae being present in the food supply.
Elimination of L. monocytogenes from biofilms in floor drains: L. monocytogenes can form a biofilm in floor drains and thus colonize poultry processing plants. This organism is very difficult to remove from a drain once a biofilm has been established. We developed a system to create a L. monocytogenes biofilm in simulated floor drains made of PVC. We then planned and conducted a series of experiments to measure the disruption of biofilms using an ultrasonic treatment to loosen the physical structure followed by application of sanitizers. Limited success has indicated the need for a different combination of treatments and the study is being continued. Once completed these data may demonstrate a novel means to remove this deadly pathogen from an important site of poultry plant colonization.
Antimicrobial resistance of L. monocytogenes: The antimicrobial resistance of L. monocytogenes found in the environment of poultry further processing plants has not been reported. If drug resistant strains are common in this arena, the potential would exist for contamination of fully cooked ready-to-eat product with drug resistant L. monocytogenes. We conceived of, planned and completed a study to measure the antimicrobial resistance of L. monocytogenes isolates detected in a poultry further processing facility. This large group of isolates is unique because it had been collected over a year long study in a commercial plant. Most of the L. monocytogenes isolates were susceptible to all antimicrobials. However, some were resistant to ceftriaxone, oxacillin, ciprofloxacin, clindamicin, tetracycline or some combination of these. The data are useful to scientists attempting to determine the importance of L. monocytogenes in processing plants and tracking the acquisition of drug resistance in such bacteria.
Microbial community structure in the Upper Oconee River watershed: The ecological distribution of human pathogens commonly associated with agricultural products is not well known. Samples were collected from 84 sites on the Upper Oconee River watershed and the isolated bacteria were subtyped to identify the distribution of clones. Clones of Salmonella, Enterococcus, and Campylobacter were found to be clustered in areas in the rivers with a radius of about 2 kilometers, which is far larger than expected for organisms found in soil samples yet still limited enough to suggest that environmental contamination occurs as a bolus or with seepage from a point source with rapid extinction of the clone. Better descriptions of bacterial communities will help to learn ways to intervene in pathogen trafficking.
Microbial ecology of major Southern river systems: The presence of a wide variety of bacteria of interest in large southern rivers that are used for commercial traffic is not widely reported. A survey study is underway of water samples from large southeastern river systems including the Mississippi, the Missouri and the Tennessee as well as contributors to the Illinois and the Alabama Rivers were collected, analyzed for presence of Campylobacter, Enterococcus, E. coli and Salmonella. Protocols for isolation of Campylobacter are being improved and plans for broadening of the geographic scope of the project are being developed. All isolates have been preserved and tested for antimicrobial resistance and subtyped. These data will be analyzed and the results will show the distribution of bacteria and also will be of interest to water quality scientists.