Antimicrobial peptides disrupting the bacterial membrane reduce <i>Salmonella</i> colonization in chickens

<i>Salmonella</i> is a significant food safety and public health concern. Poultry products have been considered the main vehicles of <i>Salmonella</i> infections in humans. <i>Salmonella</i> being present in visually healthy poultry is suggested as the preeminent human transmission risk factor, allowing bacteria to easily transmit from eggs and poultry to humans. Antimicrobial peptides (AMPs) have been suggested as promising alternatives to current antibiotics because of their low propensity for resistance development. In this study, we tested the efficacy of <i>Lactobacillus rhamnosus</i> GG (LGG)-derived small peptides (P1-NPSRQERR, P2- PDENK, and P4-MLNERVK) against <i>Salmonella</i> Typhimurium (ST) and <i>Salmonella</i> Enteritidis (SE) both <i>in vitro</i> and in chickens. Peptides inhibited ST, SE, and other public health-relevant <i>Salmonella</i> serovars <i>in vitro</i>. The antibacterial activity of peptides is likely due to their effect on <i>Salmonella</i> membranes. Importantly, P1 and P2 effectively reduced the colonization of ST by 2.2 and 1.8 logs, respectively, in chickens at 7 days post-infection. P1, P2, and P4 possessed no adverse effect on chicken cecum microbial community, but chickens not treated and challenged with <i>Salmonella</i> showed a difference in microbial richness and evenness compared to the unchallenged chickens. Furthermore, peptides retain their activity upon exposure to heat and protease treatments-characteristics necessary for the use of antimicrobial products in the poultry industry. In summary, these small peptides can provide a promising approach to develop novel strategies for controlling <i>Salmonella</i> infections in chickens.IMPORTANCE<i>Salmonella</i> is the most frequently reported bacterial cause of foodborne illness in the United States. Poultry products (eggs and poultry meat) have been considered the main vehicles of <i>Salmonella</i> infections in humans. There is a need for developing and implementing effective antibiotic alternatives to reduce <i>Salmonella</i> in chickens, minimize human exposures, and simultaneously contribute to alleviating antibiotic resistance. AMPs have been suggested as promising alternatives to current antibiotics because of their low propensity for resistance development. Our study showed that LGG-derived peptides (P1-NPSRQERR, P2-PDENK, and P4-MLNERVK) significantly inhibit ST, SE and other <i>Salmonella</i> serovars <i>in vitro</i> and in chickens. Overall, our results demonstrate that small peptides can facilitate the development of promising approaches to control <i>Salmonella</i> infections in poultry, thus contributing to improved food safety and public health.