HPMCAS-Coated Alginate Microparticles Loaded with Ctx(Ile 21 )-Ha as a Promising Antimicrobial Agent against Salmonella Enteritidis in a Chicken Infection Model.

Salmonella enterica subsp. enterica serovar Enteritidis ( S . Enteritidis) in poultry is most often transmitted by the fecal-oral route, which can be attributed to high population density. Upon encountering the innate immune response in a host, the pathogen triggers a stress response and virulence factors to help it survive in the host. The aim of this study was to evaluate the effect of hypromellose acetate/succinate (HPMCAS)-coated alginate microparticles containing the Ctx(Ile 21 )-Ha antimicrobial peptide (AMP) on both intestinal colonization and systemic infection of laying hens challenged with S . Enteritidis. The applied AMP microsystem reduced the bacterial load of S . Enteritidis in the liver, with a statistical significance between groups A (control, no Ctx(Ile 21 )-Ha peptide) and B (2.5 mg of Ctx(Ile 21 )-Ha/kg) at 2 days postinfection (dpi), potentially indicating the effectiveness of Ctx(Ile 21 )-Ha in the first stage of infection by S . Enteritidis. In addition, the results showed a significant decrease in the S . Enteritidis counts in the spleen and cecal content at 5 dpi; remarkably, no S . Enteritidis counts were observed in livers at 5, 7, and 14 dpi, regardless of the Ctx(Ile 21 )-Ha dosage ( p -value <0.0001). Using the Chi-square test, the effect of AMP microparticles on S . Enteritidis fecal excretion was also evaluated, and a significantly lower bacterial excretion was observed over 21 days in groups B and C, in comparison with the untreated control ( p- value <0.05). In summary, the use of HPMCAS-Ctx(Ile 21 )-Ha peptide microcapsules in laying hens drastically reduced the systemic infection of S . Enteritidis, mainly in the liver, indicating a potential for application as a feed additive against this pathogen.