New salmonella hazard uncovered for egg processors

23-Dec-2009 - Last updated on 16-Mar-2017 at 04:54 GMT

Wooden shelving on carts typically used for transporting eggs into processing plants can harbour salmonella-causing bacteria, a new study from the US Department of Agriculture has warned.

The microbial survey carried out by USDA’s Agriculture Research Service (ARS) said that plywood nest run carts used to carry eggs can contain Enterobacteriaceae, a bacterial family that includes the human pathogens Salmonella and Shigella. These microbes are known to contaminate the shell egg processing environment, said the body, adding their presence in high levels in processing plants “can signal inadequate sanitation”.

The research, published in the Journal of Food Protection, said little is known about the number of genera and species that contribute to nest run cart contamination. These carts are used to transport eggs that are produced by hens not housed in buildings connected to a processing plant.

Methodology

The body said the results were part of a larger survey conducted last year. Researchers took swabs from two plants in the south-eastern United States to determine location, bacterial profile and levels in the egg production line.

ARS egg quality researchers Michael Musgrove and Deana Jones found 100 per cent prevalence for Enterobacteriaceae on nests run carts at one plant and 80 percent at the other. Species of Escherichia, Enterobacter, Klebsiella, and Salmonella, among others, were present. Pseudomonas was the only non-Enterobacteriaceae identified in the survey, said a statement from the Georgia-based body.

Each cart contained 15 unpainted plywood shelves. Swab samples were taken from the cart shelves. A wide range of genera was detected – with escherichia and Enterobacter most often present compared to other Enterobacteriaceae, said the study.

Safety tool

The ARS outlined the significance of the research as a tool for improving safety by pinpointing which bacteria are likely to thrive and where to find them.

“Knowing which bacteria are present and their location are vital pieces of information in developing strategies to reduce and remove bacterial contamination,” said the group.

It added: “The findings of this survey will be used by microbiologists working with the shell egg industry and regulators to encourage development of better sanitation procedures or the use of more easily-cleaned shelving materials.”