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

Homer's Rivals? Internal Narrators in the Iliad

Homer’s authority is everywhere in the ancient world; from biography to history, art and literature, yet the two poems which have come down to us under his name tell us nothing about their author. Unlike their near contemporary Hesiod, who is very forthcoming about biographical details and family quarrels, neither the Iliad nor the Odyssey – though they contain plenty of first person pronouns referring to the ‘poet’ – give us anything like that kind of detail.1 Presumably this helped to make his later biographical tradition so rich and contested, but it poses an interesting problem for any interpreter of Homeric poetry: why, in a world in which who you are matters as much as what you say, is this absent figure granted so much authority? What is it about his poetry that makes Homer such a uniquely trusted figure in the history of ancient narrative? Though modern scholars have approached this question from a number of angles, the particular approach in this chapter has not, to my knowledge, been explored before, or at least not in this way. And that is perhaps rather fitting for the strategy with which we are concerned