An investigation of the diversity of strains of enteroaggregative Escherichia coli isolated from cases associated with a large multi-pathogen foodborne outbreak in the UK.
Following a large outbreak of foodborne gastrointestinal (GI) disease, a multiplex PCR approach was used retrospectively to investigate faecal specimens from 88 of the 413 reported cases. Gene targets from a range of bacterial GI pathogens were detected, including Salmonella species, Shigella species and Shiga toxin-producing Escherichia coli, with the majority (75%) of faecal specimens being PCR positive for aggR associated with the Enteroaggregative E. coli (EAEC) group. The 20 isolates of EAEC recovered from the outbreak specimens exhibited a range of serotypes, the most frequent being O104:H4 and O131:H27. None of the EAEC isolates had the Shiga toxin (stx) genes. Multilocus sequence typing and single nucleotide polymorphism analysis of the core genome confirmed the diverse phylogeny of the strains. The analysis also revealed a close phylogenetic relationship between the EAEC O104:H4 strains in this outbreak and the strain of E. coli O104:H4 associated with a large outbreak of haemolytic ureamic syndrome in Germany in 2011. Further analysis of the EAEC plasmids, encoding the key enteroaggregative virulence genes, showed diversity with respect to FIB/FII type, gene content and genomic architecture. Known EAEC virulence genes, such as aggR, aat and aap, were present in all but one of the strains. A variety of fimbrial genes were observed, including genes encoding all five known fimbrial types, AAF/1 to AAF/V. The AAI operon was present in its entirety in 15 of the EAEC strains, absent in three and present, but incomplete, in two isolates. EAEC is known to be a diverse pathotype and this study demonstrates that a high level of diversity in strains recovered from cases associated with a single outbreak. Although the EAEC in this study did not carry the stx genes, this outbreak provides further evidence of the pathogenic potential of the EAEC O104:H4 serotype.
Gastrointestinial Bacteria Reference Unit, Public Health England, London, United Kingdom.
Timothy J
TJ
Dallman
Gastrointestinial Bacteria Reference Unit, Public Health England, London, United Kingdom.
Marie A
MA
Chattaway
Gastrointestinial Bacteria Reference Unit, Public Health England, London, United Kingdom.
Lauren A
LA
Cowley
Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, Public Health England, London, United Kingdom.
Michel
M
Doumith
Applied Laboratory and Bio- Informatics Unit, Public Health England, London, United Kingdom.
Rediat
R
Tewolde
Department for Bio-analysis and Horizon Technologies, Next Generation Sequencing, Public Health England, London, United Kingdom.
David J
DJ
Wooldridge
Applied Laboratory and Bio- Informatics Unit, Public Health England, London, United Kingdom.
Anthony
A
Underwood
Public Health Laboratory London, Barts & The London Hospital Trust, London, United Kingdom.
Derren
D
Ready
Innovation Centre, University of East Anglia, Norwich, United Kingdom.
John
J
Wain
North East Public Health England Centre, Newcastle upon Tyne, United Kingdom.
Kirsty
K
Foster
Gastrointestinial Bacteria Reference Unit, Public Health England, London, United Kingdom.
Kathie A
KA
Grant
Gastrointestinial Bacteria Reference Unit, Public Health England, London, United Kingdom.
Claire
C
Jenkins
D044822:Biodiversity; D002874:Chromosome Mapping; D004196:Disease Outbreaks; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D005517:Foodborne Diseases / Q000453:epidemiology* / Q000382:microbiology*; D023061:Gene Order; D016680:Genome, Bacterial; D023281:Genomics; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D009876:Operon; D010641:Phenotype; D010802:Phylogeny; D010957:Plasmids; D012189:Retrospective Studies; D006113:United Kingdom / Q000453:epidemiology; D014774:Virulence / Q000235:genetics