Natural Horizontal Gene Transfer of Antimicrobial Resistance Genes in spp. From Turkeys and Swine.

Antibiotic-resistant constitutes a serious threat to public health. The clonal expansion of resistant strains and/or the horizontal spread of resistance genes to other strains and species can hinder the clinical effectiveness of antibiotics to treat severe campylobacteriosis. Still, gaps exist in our understanding of the risks of acquisition and spread of antibiotic resistance in . While the transfer of antimicrobial resistance genes between species natural transformation has been extensively demonstrated, experimental studies have favored the use of naked DNA to obtain transformants. In this study, we used experimental designs closer to real-world conditions to evaluate the possible transfer of antimicrobial resistance genes between strains of the same or different species ( or ) and originating from different animal hosts (swine or turkeys). This was evaluated through co-culture experiments and with dual-strain inoculation of turkeys, followed by whole genome sequencing of parental and newly emerged strains. , we observed four independent horizontal gene transfer events leading to the acquisition of resistance to beta-lactams (), aminoglycosides [ and ] and tetracycline []. Observed events involved the displacement of resistance-associated genes by a mutated version, or the acquisition of genomic islands harboring a resistance determinant by homologous recombination; we did not detect the transfer of resistance-carrying plasmids even though they were present in some strains. , we recovered a newly emerged strain with dual-resistance pattern and identified the replacement of an existing non-functional by a functional in the recipient strain. Whole genome comparisons allowed characterization of the events involved in the horizontal spread of resistance genes between following co-culture and dual inoculation. Our study also highlights the potential for antimicrobial resistance transfer across species originating from turkeys and swine, which may have implications for farms hosting both species in close proximity.