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Title: Enterobacteriaceae and related organisms isolated from nest run cart shelves in commercial shell egg processing facilities

item Musgrove, Michael
item Jones, Deana
item Shaw, Jordan

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2009
Publication Date: 10/1/2010
Citation: Musgrove, M.T., Jones, D.R., Shaw, J.D., Sheppard, M., Harrison, M.A. 2010. Enterobacteriaceae and related organisms isolated from nest run cart shelves in commercial shell egg processing facilities. Poultry Science. 88:2113-2117.

Interpretive Summary: Enterobacteriaceae, a bacterial family that includes human enteropathogens such as Salmonella and Shigella, are known to contaminate the shell egg processing environment. However, little information is known as to the number or genera and species that contribute to contamination of nest run cart shelves. Nest run carts are used to transport eggs from hens housed remotely from the processing facility, directly to the processing chain. Each cart contains 15 unpainted plywood shelves. Swab samples of shelves were obtained from carts at two commercial processing facilities. Enterobacteriaceae were enumerated and isolates were identified biochemically. A wide range of genera were recovered but Escherichia and Enterobacter were recovered most often, compared to other Enterobacteriaceae. This information will be used by microbiologists working with the shell egg industry, regulators, and academic researchers and will encourage the development of better sanitation procedures or the use of more easily cleaned shelving materials.

Technical Abstract: Enterobacteriaceae, including Salmonella may be recovered from foods and processing facilities. High levels of Enterobacteriaceae in the processing plant environment can be an indication of inadequate sanitation. This experiment was designed to determine if nest run egg carts serve as reservoirs for Enterobacteriaceae. Eggs that are produced by hens not housed in buildings connected to the processing plant are referred to as nest run. These eggs are transported to the plant on carts to be processed. Two plants in the Southeastern United States were sampled. On each of three visits, five shelves on each of five carts were sampled (n=25/visit). A 12 x 12 cm area on each shelf was swabbed with a sterile gauze pad moistened with phosphate buffered saline and transported on ice back to the laboratory. Enterobacteriaceae were enumerated using violet red bile glucose agar incubated at 37oC for 24 h. There was 100% prevalence for Enterobacteriaceae at plant A with an average 3.8 log cfu/mL swab diluent. Plant B had 80% prevalence for Enterobacteriaceae with an average 3.2 log cfu/mL swab diluent. Two randomly selected isolates from each positive sample were re-cultured three times to assure clonality and were then identified biochemically. Of the 124 isolates analyzed, genera identified were Citrobacter spp., Escherichia spp., Enterobacter spp., Klebsiella spp., Hafnia spp., Kluyvera spp., Leclercia spp., and Salmonella spp. Pseudomonas spp. was the only non-Enterobacteriaceae identified by our methods. This work demonstrates that nest run egg carts serve as reservoirs for Enterobacteriaceae in the shell egg processing environment.