HPMCP-coated microcapsules containing the Ctx(Ile21)-Ha antimicrobial peptide reduces the mortality rate caused by resistant Salmonella Enteritidis in poultry

The constant use of synthetic antibiotics as growth promoters can cause great bacterial resistance in chicks. Consequently, the use of these drugs has been restricted in different countries. Antimicrobial peptides have gained relevance in recent years due to their minimal capacity for bacterial resistance and does not generate toxic residues that harm the environment and human health. In this work, Ctx(Ile21)-Ha antimicrobial peptide was employed, due to its previously reported largely antimicrobial potential, to evaluate its application effect in laying chicks challenged with Salmonella Enteritidis, resistant to nalidixic acid and spectinomycin. For this, Ctx(Ile21)-Ha was synthesized, microencapsulated and coated with hypromellose phthalate (HPMCP) to be release in the intestine. Two different doses (3.2 and 6.4 {micro}g of Ctx(Ile21)-Ha per kg of isoproteic and isoenergetic poultry feed) were included in the chicks food and administered for 28 days. Antimicrobial activity, effect and response as treatment were evaluated. Statistical results were analyzed in detail and indicate that the formulated Ctx(Ile21)-Ha peptide had a positive and significant effect in relation to the reduction of chick mortality. There was a significant difference in laying chick weight between the control and microencapsulation treatment groups as a function of time. Therefore, the microencapsulated Ctx(Ile21)-Ha antimicrobial peptide may be an interesting and promising option in the substitution of conventional antibiotics.