Bacterial warfare is associated with virulence and antimicrobial resistance

The authors show that in Escherichia coli (E. coli), genes encoding bacteriocins—protein toxins used to kill or inhibit other bacteria—are disproportionately found in extra-intestinal pathogenic strains (ExPEC) and frequently co-located on large plasmids together with virulence factors (especially iron-acquisition systems) and antimicrobial-resistance (AMR) genes. They find that such bacteriocin-encoding plasmids are highly mobile (via conjugation and transposons), often carry “orphan” immunity genes (suggesting active competition rather than only plasmid-addiction), and in some cases are shared between genera (e.g., E. coli and Salmonella enterica). Their findings imply that bacterial warfare via bacteriocins helps pathogenic, drug-resistant strains to colonise and persist in competitive environments (such as the inflamed gut), linking competition, virulence and resistance in a novel way.