Novel Insights and Features of the NDM-5-Producing Escherichia coli Sequence Type 167 High-Risk Clone

Abstract

Escherichia coli sequence type 167 (ST167), producing the metallo beta-lactamase NDM-5, has been isolated as a colonizer of patients recovered at the University Hospital Policlinico Umberto I of Rome. Phylogenesis and comparative analysis of the genomes of these strains were performed against 343 ST167 genomes available from the EnteroBase database. These analyses revealed that resistance plasmids, integrative conjugative elements (ICEs), carrying the yersiniabactin virulence trait and capsular synthesis gene clusters had variable compositions and distributions within different strains of the ST167 clone. A novel capsular synthesis gene cluster, highly similar to the K48 cluster previously described only for Klebsiella pneumoniae, was identified in phylogenetically related strains of the ST167 clone.IMPORTANCE Global dissemination of some E. coli high-risk clones has been described in the last decades. The most widespread was the ST131 clone, associated with extended-spectrum-beta-lactamase (ESBL) production. Genomics of ST131 demonstrated that one clade within the ST emerged in the early 2000s, followed by a rapid, global expansion. The E. coli ST167 clone is emerging throughout the world, being frequently reported for its association with carbapenem resistance. Our study shows that virulence features are differently represented within the ST167 population. One clade shows the K48 capsular synthesis gene cluster of K. pneumoniae, not previously described for E. coli, and is populated by NDM-5-producing strains. The combination of resistance and virulence may sustain the global expansion of this specific ST167 clade.

Keywords: Escherichia coli; capsular polysaccharide; carbapenems.