Egg Processing Plant Carts Can Harbor
Bacteria By Sharon Durham December 18, 2009
Plywood-shelved carts that are used to transport eggs into processing
plants can harbor Enterobacteriaceae, according to a microbial survey
conducted by Agricultural Research
Service (ARS) scientists in Athens, Ga.
Enterobacteriaceae, a bacterial family that includes the human
pathogens Salmonella and Shigella, are known to contaminate the
shell egg processing environment. High levels of these bacteria in the
processing plant can signal inadequate sanitation.
However, little is known about the number of genera and species that
contribute to contamination of what are called nest run carts. Eggs that are
produced by hens not housed in buildings connected to the processing plant are
called nest run eggs. These eggs are transported to the plant on the carts to
The results were part of a larger survey conducted in 2008. Swab
samples were taken from two plants in the southeastern United States during
three visits to determine location, bacterial profile and levels in the egg
production line. Food technologists
Jones in the
Egg Safety and Quality Research Unit at the
B. Russell Research Center in Athens found 100 percent 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.
Each cart contained 15 unpainted plywood shelves. Musgrove and Jones
took swab samples from the cart shelves and recovered a wide range of genera,
but Escherichia and Enterobacter were present most often compared
to other Enterobacteriaceae.
Knowing which bacteria are present and their location are vital pieces
of information in developing strategies to reduce and remove bacterial
contamination. 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
This research was published in the Journal
of Food Protection.
This research supports the U.S.
Department of Agriculture (USDA) priority of ensuring food safety. ARS is
USDAs principal intramural scientific research agency.