Shiga Toxinaproducing Escherichia coli Strains Negative for Locus of Enterocyte Effacement

The ehx plasmids of these strains are highly related, which suggests acquisition of the large plasmid was central to the strainsa emergence. Most Shiga toxinaproducing Escherichia coli (STEC) infections that are associated with severe sequelae such as hemolytic uremic syndrome (HUS) are caused by at...

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Bibliographic Details
Published in:Emerging infectious diseases 2009-03, Vol.15 (3), p.372-380
Main Authors: Newton, Hayley J, Sloan, Joan, Bulach, Dieter M, Seemann, Torsten, Allison, Cody C, Tauschek, Marija, Robins-Browne, Roy M, Paton, James C, Whittam, Thomas S, Paton, Adrienne W, Hartland, Elizabeth L
Format: Article
Language:English
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Escherichia coli
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Summary:The ehx plasmids of these strains are highly related, which suggests acquisition of the large plasmid was central to the strainsa emergence. Most Shiga toxinaproducing Escherichia coli (STEC) infections that are associated with severe sequelae such as hemolytic uremic syndrome (HUS) are caused by attaching and effacing pathogens that carry the locus of enterocyte effacement (LEE). However, a proportion of STEC isolates that do not carry LEE have been associated with HUS. To clarify the emergence of LEE-negative STEC, we compared the genetic composition of the virulence plasmids pO113 and pO157 from LEE-negative and LEE-positive STEC, respectively. The complete nucleotide sequence of pO113 showed that several plasmid genes were shared by STEC O157:H7. In addition, allelic profiling of the ehxA gene demonstrated that pO113 belongs to a different evolutionary lineage than pO157 and that the virulence plasmids of LEE-negative STEC strains were highly related. In contrast, multilocus sequence typing of 17 LEE-negative STEC isolates showed several clonal groups, suggesting that pathogenic LEE-negative STEC has emerged several times throughout its evolution.
ISSN:1080-6040
1080-6059
DOI:10.3201/eid1502.080631