Location: Poultry Microbiological Safety and Processing Research UnitTitle: Impact of cold storage and incubation of hatching eggs on the recovery of inoculated Salmonella Enteritidis or Campylobacter coli into to yolk or albumen
Submitted to: Poultry Science Association
Publication Type: Abstract Only
Publication Acceptance Date: 5/26/2022
Publication Date: 7/11/2022
Citation: Harris, C.E., Bartenfeld Jossel, L.N., Buhr, R.J. 2022. Impact of cold storage and incubation of hatching eggs on the recovery of inoculated Salmonella Enteritidis or Campylobacter coli into to yolk or albumen. Poultry Science Association. p. 136.
Technical Abstract: Salmonella and Campylobacter are important foodborne pathogens and increased knowledge on the potential for egg transmission is beneficial when developing intervention strategies. Data is lacking for Campylobacter verifying vertical egg transmission but confirmed for Salmonellae. The objective was evaluating recovery of Salmonella Enteritidis (SE; exp 1) or Campylobacter coli (CC; exp 2) when injected into albumen (AL) or yolk (YO) of hatching eggs that were cold stored then incubated. For both exps, 240 SPF White Leghorn eggs were placed into 2 trt (n=120 AL and YO). On D0, 10^3 CFU SE or CC inoculum was injected into albumen or yolk. Eggs were stored for 2d (6C; 54%RH) and transferred to incubator for 15d (37.5C; 55% RH). Fifteen eggs/trt were sampled on d0, storage days (S1 and S2), and days 1, 5, and 15 incubated (D1, D5, and D15). Total egg contents were sampled on d0, S1, S2, and D1. For D5 and D15, viable embryos were aseptically removed and sampled separately from egg contents. Direct and enriched plating was performed for egg contents/embryos in duplicate. Direct counts were analyzed with ANOVA and enrich results were analyzed with Kruskal-Wallis test to determine significance (p=0.05). On d0, all samples were direct positive for exp 1 and 2. In exp 1, SE counts were similar for both S1 (0.9 Log10 AL and YO) and S2 (0.9 Log10 AL and 0.7 Log10 YO). There was a significant difference in direct recovery of SE on E1 (0% AL vs. 100% YO); both were 100% following enrichment. SE recovery from egg contents on D5 and D15 were significantly different with YO 100% positive and AL 33 - 57% positive. For exp 1, no viable embryos were collected for YO and 1 viable embryo from AL was positive for SE on D5. In exp2, no significant difference in CC direct counts occurred on S1 (1.3 Log10 AL vs. 1.8 Log10 YO), but there was a significant difference in recovery on S2 (13% AL vs. 100% YO). YO had higher direct counts (0 vs. 1.0 Log10) and enrich recovery (0% vs. 87%) on E1 compared to AL. For egg contents, there was a significant difference in recovery on E5 (0% AL vs. 100% YO), but no significant difference on E15 (0% AL vs. 9% YO). For YO, 11 viable embryos were sampled on E15, and there was a significant difference in enrich recovery (0% AL vs. 45% YO). The lack of viable embryos for exp 1 indicates that it is unlikely that SE contaminates the yolk of developing eggs, rather, it may be contaminating the vitelline membrane or albumen. In comparison, a small number of embryos survived to D15 of incubation when the yolks were injected with CC. Results confirm that AL/YO inoculation, cold storage for 2d, and then incubation is a possible method to study vertical transmission of Campylobacter during incubation.