Genome Sequences Reveal Antimicrobial Resistance Gene Dynamics

In Nature Communications, researchers from the University of East Anglia, the Quadram Institute of Bioscience, and other centers in the UK, Canada, France, and Germany explore the spread of antimicrobial resistance (AMR) genes in Escherichia coli and other Enterobacterales-order microbes, focusing on extended-spectrum cephalosporin resistance (ESC-R) genes. With whole-genome sequences for 1,930 isolates collected at clinical, domestic animal, food processing, wastewater, and other environmental sites in Europe and North America between 2008 and 2016, the team tracked the dynamics and distribution of plasmids and bacterial clones carrying beta-lactamase enzyme-coding genes that contribute to ESC antibiotic resistance. While plasmid-mediated AmpC beta-lactamase enzymes were found in farm animal and human samples collected in North America before appearing in Europe, for example, extended-spectrum beta-lactamase enzymes showed the opposite pattern, emerging in North America later on, after dominating in the early European animal samples. "This study identifies differences in the relative importance of plasmids and clonal expansion across different compartments for the spread of different ESC-R genes," the authors write. "Understanding the mechanisms of transmission will be critical in the design of interventions to reduce the spread of antimicrobial resistance."