Evidence for Neolithic acquisition of the high pathogenic island by Escherichia coli followed by recent selection

Many genetic elements involved in virulence and pathogenicity have been identified in commensal bacteria that are also opportunistic pathogens, but how these elements evolve is less well known. Understanding the evolutionary history of virulence elements requires genomes sampled in commensalism in healthy hosts, as genomes from bacterial infections are biased towards higher pathogenicity. Here, using a rare collection of human commensal Escherichia coli sampled in France from 1980 to 2020, we inferred the evolutionary history of the High Pathogenicity Island (HPI), a key virulence factor of E. coli with an uncertain evolutionary origin. We showed that the HPI was horizontally transferred from Yersinia pestis to E. coli and other Enterobacterales approximatively 4,800 years ago, coinciding with a period of high prevalence of the plague in the Neolithic. The element subsequently spread in the whole species and in Klebsiella pneumoniae, with signs of positive epistasis with phylogroups B2 and F, and was positively selected in the last 100 years. Our work sheds light on the history and mode of evolution of virulence in an important opportunistic pathogen. It suggests the Neolithic period may have favored not only the emergence of zoonotic pathogens but also gene transfer between bacterial species, enriching the gene repertoire of major pathogens with potentially important implications on public health nowadays.