Karolina Tarsalewska

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.