Listeria Occurrence in Conventional and Alternative Egg Production Systems

Authors: RICKE, STEVEN - University Of Wisconsin; OBRYAN, CORLISS - University Of Arkansas; Rothrock, Michael

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2023
Publication Date: 8/27/2023
Citation: Ricke, S.C., Obryan, C.A., Rothrock Jr, M.J. 2023. Listeria Occurrence in Conventional and Alternative Egg Production Systems. Microorganisms. https://doi.org/10.3390/microorganisms11092164.
DOI: https://doi.org/10.3390/microorganisms11092164

Interpretive Summary: Listeria 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. Listeria is considered a saprophytic organism with the capability to respond and adapt to constantly changing environments because they possess 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 Listeria, but the potential for contamination during egg production and processing does exist. Listeria species have been isolated from egg processing plant equipment and presumed to occur in egg processing plant environments. Whether Listeria 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 inhibitory to Listeria. Even less is known regarding the association of Listeria with alternative egg production systems, but Listeria 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 Listeria and their eggs become contaminated. The review focuses on the possibility for Listeria to occur in conventional and alternative egg laying production and processing systems

Technical Abstract: Listeria 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. Listeria is considered a saprophytic organism with the capability to respond and adapt to constantly changing environments because they possess 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 Listeria, but the potential for contamination during egg production and processing does exist. Listeria species have been isolated from egg processing plant equipment and presumed to occur in egg processing plant environments. Whether Listeria 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 inhibitory to Listeria. Even less is known regarding the association of Listeria with alternative egg production systems, but Listeria 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 Listeria and their eggs become contaminated. The review focuses on the possibility for Listeria to occur in conventional and alternative egg laying production and processing systems.