With the primary driving force for resistance development being the overuse of antibiotics, technologies are being sought to limit their injudicious use, particularly in food-producing animals. Over 70% of the antibiotics produced in the U.S. are consumed by livestock for growth promotion and prophylaxis purposes. This continuous, sub-therapeutic administration applies a selective pressure on the animal microflora which may facilitate the evolution of resistance development. These resistant microbes can then be transmitted to consumers on contaminated food products.
We have developed an antibiotic-alternative to decrease Salmonella carriage in pre-harvest poultry by engineering probiotic bacteria with significant anti-Salmonella activity. We modified the probiotic, E.coli Nissle 1917 (EcN), to produce high-titers of the antimicrobial peptide (AMP), Microcin J25, which elicits strong antagonistic activity against Salmonella enteritidis. AMPs have been researched for decades for their antibiotic properties but have failed in translational success due to their high synthesis costs and rapid degradation in the body. Our novel use of a probiotic delivery vector has overcome these hurdles, enabling localized production among the host’s natural microflora. Our in vivo studies, including over 300 commercial turkey poults, demonstrate that a single treatment of the modified EcN is capable of dramatically reducing SE carriage in the intestinal tract of poultry with better clearance than the traditional antibiotic, enrofloxacin.