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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Poultry Microbiological Safety and Processing Research Unit » Research » Publications at this Location » Publication #352786
Research Project: Production and Processing Intervention Strategies for Poultry Associated Foodborne Pathogens

Location: Poultry Microbiological Safety and Processing Research Unit

Title: Impact of egg holding temperatures on the recovery of salmonella from eggshells and stainless steel coupons

Author
item Buhr, Richard - Jeff
item BOURASSA, DIANNA - Auburn University
item WILSON, KIMBERLY - Ohio University

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2018
Publication Date: 4/25/2018
Citation: Buhr, R.J., Bourassa, D.V., Wilson, K.M. 2018. Impact of egg holding temperatures on the recovery of salmonella from eggshells and stainless steel coupons. Poultry Science Association Meeting Abstract. 97(E-Suppl.1)229. p.96.

Interpretive Summary: none

Technical Abstract: This experiment was conducted to determine the impact of egg holding temperature on the ability to recover Salmonella from eggshells after 24 h. Salmonella enterica Enteritidis (nalidixic acid resistant marker strain) inoculated eggshells and stainless steel coupons (SSC, 14 mm diameter) were held at 24, 19, or 7C for 24 h prior to sampling. These three holding temperatures represent environments that eggs could be kept at after lay; room temperature, egg cooler (hatching eggs), or refrigerated (table eggs). Inoculated SSC were used to assess the survivability of the inoculated Salmonella on a non-eggshell surface. Inoculated eggs and SSC were also placed in a freezer at -15C and served as an additional treatment group. In the first trial, eggs were challenged with Salmonella inoculum at either 10,000 or 100,000 CFU/10 µL and in the second trial eggs and SSC were challenged with Salmonella inoculum at 100,000 CFU/10 µL. After holding, the inoculated eggs were cracked on a clean aluminum foil surface and the internal contents were discarded. Eggshells were crushed in a gloved hand and put into a 50 mL centrifuge tube. Each sample received 30 mL of 1% buffered peptone water and was incubated at 37C for 18 to 24 h. Two loops (20 µL) of eggshell or SSC rinsates were streaked onto Brilliant Green Sulfa agar containing 100 µg/mL nalidixic acid. Plates were incubated for 24 h at 37C, after which the plates were recorded as positive or negative. Eggshells inoculated at 10,000 or 100,000 CFU and sampled after holding at room temperature (24°C) for 1 h had recovery from 80 to 97% Salmonella positive, indicating a successful challenge. In the first trial inoculated eggs held for 24 h at 24, 19, or 7C had low recovery of Salmonella from 0 to 27% (0 to 1/15 for inoculum at 10,000 CFU and 0 to 4/15 for inoculum at 100,000 CFU). In the second trial eggs and SSC inoculated at 10,000 CFU and sampled after 1 h had Salmonella recovery of 97% (29/30) for eggshells compared to 93% (14/15) for SSC. However, Salmonella recovery after 24 h significantly differed (P <0.05) between samples held at -15C (0% for eggshells vs. 93% for SSC); samples held at 7C (57% for eggshells vs. 100% for SSC); samples held at 19C (0% for eggshells and 87% for SSC); and for those samples held at 24C (20% for eggshells and 100% for SSC). Overall for the second trial after holding for 24 h at 24, 19, or 7C, Salmonella was recovered from only 19% (23/120) of the eggshells but from 95% (57/60) of the SSC. These results indicate that sampling of eggshells for Salmonella 24 h after inoculation may not accurately represent pathogen levels present at lay. Additionally, the eggshell appears to have an antimicrobial effect against Salmonella during this 24 h time period.