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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Egg Refrigeration on the in Vitro Penetration of Salmonella Enteritidis Through the Yolk Membrane.

item Gast, Richard
item Holt, Peter

Submitted to: Poultry Science Association
Publication Type: Abstract Only
Publication Acceptance Date: March 17, 2005
Publication Date: August 1, 2005
Citation: Gast, R.K., Holt, P.S. 2005. Effect of egg refrigeration on the in vitro penetration of salmonella enteritidis through the yolk membrane. Poultry Science Association. 84(1):77.

Technical Abstract: Internally contaminated eggs have been implicated as leading sources of transmission of Salmonella enteritidis to humans. Although S. enteritidis is not often deposited inside the nutrient-rich yolks of naturally contaminated eggs, penetration through the vitelline membrane to reach the yolk contents could result in rapid bacterial multiplication. Previous studies have observed such penetration to occur at a low frequency at warm temperatures using in vitro egg contamination models. The present study determined whether egg refrigeration affects the frequency of in vitro penetration of S. enteritidis across the yolk membrane. After inoculation of approximately 100 cfu of S. enteritidis onto the outside of the vitelline membranes of intact yolks in plastic tubes, the albumen was added back into each tube and the samples were either immediately refrigerated at 7E C, held for 2 or 6 hours at 30E C and then refrigerated, or held at 30E C. Twenty-four hours after inoculation of the samples, the numbers of S. enteritidis inside the yolks were determined. Refrigeration, especially when applied immediately to contaminated yolk samples, significantly reduced the penetration of S. enteritidis into the contents of egg yolks in the in vitro contamination model. These results highlight the value of prompt refrigeration for restricting the opportunities for S. enteritidis to multiply to high levels inside the yolks of contaminated eggs.

Last Modified: 4/22/2015
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