Location: Poultry Microbiological Safety and Processing Research UnitTitle: Evaluation of protocol to study Salmonella and Campylobacter spp. inovo transmission via inoculation and incubation of hatching eggs
Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/7/2021
Publication Date: 7/19/2021
Citation: Harris, C.E., Bartenfeld Jossel, L.N., Buhr, R.J. 2021. Evaluation of protocol to study Salmonella and Campylobacter spp. inovo transmission via inoculation and incubation of hatching eggs. Poultry Science Association. Meeting Abstract.
Interpretive Summary: n/a
Technical Abstract: Salmonella and Campylobacter spp. are important foodborne pathogens, and increased knowledge on egg transmission would be beneficial for intervention strategies. There is documentation that Salmonella spp. can be transmitted from hen to egg to offspring, but the data is lacking for Campylobacter The objective of this project was to evaluate an inoculation and recovery protocol for hatching eggs using S. Enteritiditis (SE) as a potential way to study egg transmission for both Salmonella and Campylobacter. Two experiments were performed using 2 SE inoculum levels: 10^2 (exp 1), 10^3 (exp2), and buffered peptone water (BPW, negative control). For both experiments, SPF white Leghorn eggs were divided into 2 treatments, SE or BPW inoculated (n=78). On d0, a hole along the equator of the egg was ground and inoculum was injected into the albumen before incubation. Eggs were incubated at 37.5C, 54% relative humidity, and turned every hour. Three eggs/treatment were sampled on d0 to confirm inoculation, and 30 eggs/treatment were sampled on d5 and d15 of incubation. Embryos were aseptically removed and sampled separately from egg contents. Direct and enriched plating were performed to determine recovery, and mortality recorded. For direct counts, ANOVA was used to determine significance; for prevalence and mortality data, Kruskal-Wallis method was used to determine significance (p=0.05). For overall mortality, there were no significant differences (p>0.05) between the SE and BPW treatments for exp 1 (16%) and exp 2 (16% vs. 7%). For exp 1 at d5, SE counts were significantly higher for both embryos (2.79 log10/mL) and egg contents (1.97 log10/mL) compared to the BPW treatment (0 log10/mL). For d15, there were no significant differences (p=0.06) between the SE (0.32 log10) and BPW (0 log10) treatments for embryos, and no egg contents were positive with direct or enriched plating. For exp 2, there was a significant difference at d5 for SE recovery from embryos (3.11 log10) and egg contents (3.16 log10) compared to eggs inoculated with BPW (0 log10). At d15, there was a significant difference in direct counts between SE (1.26 log10) and BPW (0 log10) treatments for egg contents. For embryos, there was no significant difference for direct counts (p=0.16), but recovery from enriched plating was significantly higher for SE (21% positive) vs. BPW (0% positive) treatments. These results confirm that Salmonella Enteritidis can be recovered from both embryos and egg contents of hatching eggs incubated up to 15d and be a potential protocol to study egg transmission. Further experiments with evaluate this protocol with Campylobacter spp. as well.