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United States Department of Agriculture

Agricultural Research Service

Research Project: EGG PROCESSING SAFETY, QUALITY AND SECURITY

Location: Egg Safety and Quality

Title: Attached Bacterial Cell Contamination of Shell Egg Processing Facilities

Authors
item Musgrove, Michael
item Berrang, Mark
item Liljebjelke, Karen

Submitted to: UJNR Food & Agricultural Panel Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 21, 2008
Publication Date: August 25, 2008
Citation: Musgrove, M.T., Berrang, M.E., Liljebjelke, K.A. 2008. Attached Bacterial Cell Contamination of Shell Egg Processing Facilities. UJNR Food & Agricultural Panel Proceedings. 66-67.

Technical Abstract: Sanitation is vital to providing safe, healthy food to consumers. Understanding the degree to which microorganisms persist on specific equipment or locations contributes to developing effective sanitation programs. Certain microbial populations may be used to determine areas within a processing plant that warrant an increased effort in achieving an acceptable level of sanitation. A survey of aerobic microorganisms (APC), Enterobacteriaceae and Salmonella contamination of 35 sites within a single commercial shell egg processing plant was conducted on four visits. Tank lids, nozzle guards, and the interior surface of the tank, spindles, brushes and belts along the processing chain, scoops, air filters, and floor drains were sampled using swabs moistened with 10 ml deactivating buffer. Samples were transported on ice to the laboratory. Each sample was stomacher blended and then duplicate plated onto plate count agar incubated for 48 h at 37oC and violet red bile glucose agar incubated overnight at 37oC to enumerate aerobic microorganisms and Enterobacteriaceae, respectively. Counts for each sample were converted to log CFU/ml and results from both visits were averaged together. Sponges for each sample were selectively enriched using conventional cultural media, incubation temperatures and times. APC levels ranged from 1.9 log CFU/ml for washer tank lid and post-wash spindles to 7.6 log CFU/ml for the pre-wash tank surface and floor drains. Enterobacteriaceae levels ranged from 0.0 log CFU/ml for wash tank nozzles, lids, post-wash spindles, and post-wash packer belt to 3.1 log CFU/ml for pre-washed egg accumulator belt, floor drains and 4.0 log CFU/ml for breaker egg diverter. Salmonella was recovered from floor drains, breaker egg diverter and breaker egg belt surfaces. A selection of isolates picked from VRBG plates were identified to genus or species using biochemical tests in an automated system. Escherichia, Enterobacter, Klebsiella, and Citrobacter were the most commonly identified Enterobacteriaceae. Cedecea neteri, Citrobacter sedakii, Enterobacter cancerogenous, Enterobacter nimipressuralis, Kluyvera cochleae, Kluyvera georgiana, Pantoea dispersa, Pantoea stewartii, Providencia rustigianii, Raoutella terrigena, and Raoultella spp. are organisms that have not been previously reported by our laboratory. High levels of APC and Enterobacteriaceae may not always provide an index of pathogen contamination but they can be used to determine locations within the processing environment where stricter hygiene is needed.

Last Modified: 8/1/2014