Listeria Occurrence in Conventional and Alternative Egg Production Systems

continues to be a persistent foodborne pathogen that is responsible for human cases of listeriosis when contaminated food products are consumed. Human subjects considered to be most susceptible include the elderly, immunocompromised, and pregnant women. is characterized as a saprophytic organism with the capability of responding and adapting to constantly changing environments because it possesses multiple stress response mechanisms to overcome varying temperatures, salt concentrations, and pH, among others. Primary foods and food products associated with listeriosis include dairy products and ready-to-eat meats such as turkey products. Historically, chicken eggs have not been identified as a primary source of but the potential for contamination during egg production and processing does exist. species have been isolated from egg-processing plant equipment and are presumed to occur in egg-processing plant environments. Whether is consistently disseminated onto eggs beyond the egg-processing plant is a risk factor that remains to be determined. However, research has been conducted over the years to develop egg wash solutions that generate combinations of pH and other properties that would be considered inhibitory to . Even less is known regarding the association of with alternative egg production systems, but has been isolated from pasture flock broilers, so it is conceivable, given the nature of the outdoor environments, that layer birds under these conditions would also be exposed to and their eggs become contaminated. This review focuses on the possibility of occurring in conventional and alternative egg-laying production and processing systems.