Page Banner

United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: INTERVENTION AND PROCESSING STRATEGIES FOR FOOD-BORNE PATHOGENS IN SHELL EGGS

Location: Egg Safety and Quality

2011 Annual Report


1a.Objectives (from AD-416)
1. Evaluate bactericidal effects of critical processing parameters (e.g. influence of wash water parameters, sanitizers, and sanitizer application methods) on egg safety. Specifically, conduct research on effective sanitizers (chemical, UV, etc.) and parameters that influence efficacy (temperature, nozzle type, etc.): 1.A Determine role of pH in wash water; 1.B Test chemicals as post-wash sanitizers for shell eggs; 1.C Evaluate modifications in post-wash sanitizer delivery.

2. Identify intervention strategies and processing practices for shell egg facilities and equipment that will improve sanitation standard operating procedures and reduce foodborne pathogens: 2.A Identify important reservoirs of Salmonella contamination in the processing environment; 2.B Evaluate sanitation interventions.

3. Develop more sensitive methods of detection and analysis and apply them in the determination and characterization of pathogen flow through the processing environment and onto eggs: 3.A Evaluate rapid, sensitive methods for pathogen detection; 3.B Utilize enhance methods to determine effect of housing on egg microbiology; 3.C: Characterize isolates at the molecular level to demonstrate flow from production through processing.


1b.Approach (from AD-416)
This project will promote egg safety by improving processing and intervention strategies in three critical areas. First, the bactericidal effects of critical processing parameters will be determined. Commercial egg wash detergents do an excellent job of cleaning eggs but are less lethal to bacteria when wash water pH is <10. Currently, the sanitizing chlorine solution sprayed onto eggs after washing does not reduce bacterial numbers. Research is needed to document the importance of pH and to identify an effective post-wash egg sanitizer. Second, improved sanitation procedures within processing facilities will be developed. Producing safe food requires a clean processing environment. Documentation is needed of areas and equipment in the processing facility most often contaminated with Salmonella. Such information will assist in development of effective means of removing or killing harmful bacteria. Third, better methods for detecting pathogens in egg processing environments and eggs will be developed. A recent new law requires egg producers to test for Salmonella Enteritidis (SE) in houses and flocks. Rapid, objective tests specific for SE will enable the egg industry in complying with this rule. Analyzing DNA from Salmonella collected at farms, processing facilities, and eggs allow for tracking of important contamination sources. Also, improved testing methods are required for a scientifically-based assessment of how different housing types affect egg microbiology.


3.Progress Report
Samples were collected from 4 layer breeder farms and enriched to recover Salmonella and Campylobacter. A single Salmonella positive was recovered from a fecal sample. Campylobacter was recovered from feces, oviduct, and drag swabs, all from two breeder farms.

A commercial facility was modified to include three types of housing systems for layer hens: traditional cages, aviary style, enriched cages, which were sampled to determine a baseline of Salmonella and Campylobacter contamination prior to hen placement. Swabs of cages, egg belts, manure belts, and floors were performed. Only the traditional cages and belts were contaminated with Salmonella. None of the samples were positive for Campylobacter.

Environmental samples were collected from hens in layer houses using traditional cages, aviary, or enriched cages. Areas sampled included egg belts, cage wiring, manure belts, egg ramps/elevators, nest area, roosts, and drag swabs of floors. Fly and rodents were sampled intermittently. From May through July; 17, 13, and 6 Salmonella positive samples were recovered from traditional, aviary, and enriched caging systems, respectively. Two fly samples from the aviary barn were also positive for Salmonella. In the same time period 8, 41, and 24 Campylobacter positive samples were recovered from traditional, aviary, and enriched caging systems, respectively. Eggs were collected from cages and from the floor. No eggs were positive for either Salmonella or Campylobacter. On a single visit to an egg processing facility, environmental, water, and egg samples were collected. Environmental sampling including, rollers, trays, transport equipment {spindles, belts}, brushes, tanks drains, and egg waste buckets. Temperature and pH readings were recorded for wash water. Eggs from each of the housing systems were collected and sampled before and after washing. None of the environmental swab samples were positive for Salmonella or Campylobacter. Pooled egg slurry prepared from unwashed eggs laid by traditionally caged hens, was positive for Salmonella. Campylobacter was recovered from pooled slurry prepared from washed eggs laid by hens housed in the enriched cages. This project replaced 6612-41420-018-00D.


Review Publications
Hannah, J.F., Wilson, J.L., Cox Jr, N.A., Cason Jr, J.A., Bourassa, D.V., Richardson, L.J., Musgrove, M.T., Rigsby, L.L., Buhr, R.J. 2011. Comparison of shell bacteria from unwashed and washed table eggs harvested from caged laying hens and cage-free floor-housed laying hens. Poultry Science. 90(7):1586-1593.

Last Modified: 8/27/2014
Footer Content Back to Top of Page