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

Abstract

<i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Enteritidis (<i>S</i>. 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(Ile²¹)-Ha antimicrobial peptide (AMP) on both intestinal colonization and systemic infection of laying hens challenged with <i>S</i>. Enteritidis. The applied AMP microsystem reduced the bacterial load of <i>S</i>. Enteritidis in the liver, with a statistical significance between groups A (control, no Ctx(Ile²¹)-Ha peptide) and B (2.5 mg of Ctx(Ile²¹)-Ha/kg) at 2 days postinfection (dpi), potentially indicating the effectiveness of Ctx(Ile²¹)-Ha in the first stage of infection by <i>S</i>. Enteritidis. In addition, the results showed a significant decrease in the <i>S</i>. Enteritidis counts in the spleen and cecal content at 5 dpi; remarkably, no <i>S</i>. Enteritidis counts were observed in livers at 5, 7, and 14 dpi, regardless of the Ctx(Ile²¹)-Ha dosage (<i>p</i>-value <0.0001). Using the Chi-square test, the effect of AMP microparticles on <i>S</i>. 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 (<i>p-</i>value <0.05). In summary, the use of HPMCAS-Ctx(Ile²¹)-Ha peptide microcapsules in laying hens drastically reduced the systemic infection of <i>S</i>. Enteritidis, mainly in the liver, indicating a potential for application as a feed additive against this pathogen.