Growth-Inhibitory Effect of Chicken Egg Yolk Polyclonal Antibodies (IgY) on Zoonotic Pathogens Campylobacter jejuni, Salmonella spp. and Escherichia coli, In Vitro

The overuse of antibiotics in animal husbandry has driven the search for alternative strategies to combat zoonotic pathogens. Foodborne zoonotic diseases caused by pathogenic bacteria pose a significant threat to human health, and therefore food safety should be a priority. This study investigates the in vitro inhibitory effects of chicken egg yolk immunoglobulin Y (IgY) on the growth and viability of three major foodborne pathogens: Campylobacter jejuni, Salmonella spp., and Escherichia coli. IgY was isolated from immunized hen egg yolks using a modified water dilution method, and its antigen-specificity confirmed through agglutination assays. Growth inhibition was evaluated across multiple doses and time points, revealing a dose-dependent bacteriostatic effect against all tested pathogens. A single dose of IgY (0.5 mg/mL) significantly reduced C. jejuni counts by up to 7 log, while repeated doses were required for Salmonella spp. and E. coli. These findings highlight egg yolk immunoglobulin's potential as a source of sustainable, effective, ethical, readily available, and inexpensive antibiotic substitutes in livestock management. Future research will focus on validating these results in vivo and exploring large-scale production of IgY for practical application in animal healthcare.