Identification of genes influencing the evolution of Escherichia coli ST372 in dogs and humans

ST372 are widely reported as the major Escherichia coli sequence type in dogs globally. They are also a sporadic cause of extraintestinal infections in humans. Despite this, it is unknown whether ST372 strains from dogs and humans represent shared or distinct populations. Furthermore, little is known about genomic traits that might explain the prominence of ST372 in dogs or presence in humans. To address this, we applied a variety of bioinformatics analyses to a global collection of 407 ST372 E. coli whole-genome sequences to characterize their epidemiological features, population structure and associated acces-sory genomes. We confirm that dogs are the dominant host of ST372 and that clusters within the population structure exhibit distinctive O:H types. One phylogenetic cluster, 'cluster M', comprised almost half of the sequences and showed the divergence of two human-restricted clades that carried different O:H types to the remainder of the cluster. We also present evidence sup-porting transmission between dogs and humans within different clusters of the phylogeny, including M. We show that multiple acquisitions of the pdu propanediol utilization operon have occurred in clusters dominated by isolates of canine source, pos-sibly linked to diet, whereas loss of the pdu operon and acquisition of K antigen virulence genes characterize human-restricted lineages.

Automated summary

ST372 is the major Escherichia coli sequence type in dogs globally and is sporadically responsible for extraintestinal infections in humans. However, it is unclear whether ST372 strains from dogs and humans represent shared or distinct populations. In this study, the authors conducted bioinformatics analyses on 407 ST372 E. coli whole-genome sequences to characterize their epidemiological features, population structure, and associated accessory genomes. The results confirm that dogs are the dominant host of ST372, with distinct clusters within the population structure exhibiting different O:H types. Evidence of transmission between dogs and humans within different clusters was also found.