The intrinsic potential of IgY-polymyxin B nanocombinations for combating colistin-resistant Salmonella enterica serovar Typhimurium isolated from ready-to-cook chicken.

Egg yolk immunoglobulin Y (IgY) derived from avian sources, such as chickens, has attracted interest due to its low cost and rapid production. This study aimed to fabricate chitosan nanoparticles conjugated with IgY antibodies and polymyxin B as novel antibacterial nanocombinations to fight multi-resistant Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) isolated from poultry. Chicken IgY was purified from egg yolk via caprylic acid precipitation and gel filtration. The developed polymyxin B-loaded nanocombinations, enhanced by IgY-polymyxin B-based NPs (IgY-Poly/ChNPs and IgY-coated-Poly/ChNPs), were designed to overcome the resistance limitations of polymyxin B. In this system, polymyxin B serves as the primary bactericidal agent, while the chitosan nanoparticle acts as a biocompatible carrier matrix, and the IgY coating serves as a functional shell to enhance stability and potentially interfere with bacterial surface attachment. The IgY-polymyxin B-based NPs exhibited a spherical morphology (124.2-290.7 nm) and a zeta potential of -26.5 to -46.9 mV. The formulations demonstrated potent inhibitory efficacy (12±0.98 - 21±0.91 mm) with MIC values of 0.125 to 2.0 mg/mL against Salmonella Typhimurium. These nanocombinations inhibited bacterial growth in a time- and dose-dependent manner. A significant downregulation of mcr-1 gene expression (3.97 to 8.7-fold) was observed in colistin-resistant Salmonella Typhimurium isolates, though this effect was isolate-dependent. SEM analysis showed extreme distortion in treated bacterial cells. Finally, the IgY-polymyxin B-based NPs showed minimal toxicity toward normal human skin fibroblast (HSF) cells, demonstrating them as possible candidates for future antimicrobial therapy.