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Genomic surveillance of Escherichia coli ST131 identifies local expansion and serial replacement of subclones.

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Ludden, Catherine 
Decano, Arun Gonzales 
Jamrozy, Dorota 
Pickard, Derek 
Morris, Dearbhaile 


Escherichia coli sequence type 131 (ST131) is a pandemic clone that is evolving rapidly with increasing levels of antimicrobial resistance. Here, we investigated an outbreak of E. coli ST131 producing extended spectrum β-lactamases (ESBLs) in a long-term care facility (LTCF) in Ireland by combining data from this LTCF (n=69) with other Irish (n=35) and global (n=690) ST131 genomes to reconstruct the evolutionary history and understand changes in population structure and genome architecture over time. This required a combination of short- and long-read genome sequencing, de novo assembly, read mapping, ESBL gene screening, plasmid alignment and temporal phylogenetics. We found that Clade C was the most prevalent (686 out of 794 isolates, 86 %) of the three major ST131 clades circulating worldwide (A with fimH41, B with fimH22, C with fimH30), and was associated with the presence of different ESBL alleles, diverse plasmids and transposable elements. Clade C was estimated to have emerged in c. 1985 and subsequently acquired different ESBL gene variants (blaCTX-M-14 vs blaCTX-M-15). An ISEcp1-mediated transposition of the blaCTX-M-15 gene further increased the diversity within Clade C. We discovered a local clonal expansion of a rare C2 lineage (C2_8) with a chromosomal insertion of blaCTX-M-15 at the mppA gene. This was acquired from an IncFIA plasmid. The C2_8 lineage clonally expanded in the Irish LTCF from 2006, displacing the existing C1 strain (C1_10), highlighting the potential for novel ESBL-producing ST131 with a distinct genetic profile to cause outbreaks strongly associated with specific healthcare environments.



Escherichia coli, ST131, antimicrobial resistance, genomics, long-term care facilities, Disease Outbreaks, Escherichia coli, Escherichia coli Infections, Evolution, Molecular, Humans, Ireland, Long-Term Care, Molecular Epidemiology, Mutagenesis, Insertional, Phylogeny, Plasmids, Sequence Analysis, DNA, beta-Lactamases

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Microb Genom

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Microbiology Society


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Wellcome Trust (098600/Z/12/Z)