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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #349608
Research Project: Genomic and Metagenomic Differences in Foodborne Pathogens and Determination of Ecological Niches and Reservoirs

Location: Meat Safety and Quality

Title: Identification of a new Shiga toxin-producing Escherichia coli O26:H11 stx2 single nucleotide polymorphism clonal complex in the United States

Author
item Bono, James - Jim
item STROCKBINE, NANCY - Centers For Disease Control And Prevention (CDC) - United States

Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2018
Publication Date: 7/1/2018
Citation: Bono, J., Strockbine, N. 2018. Identification of a new Shiga toxin-producing Escherichia coli O26:H11 stx2 single nucleotide polymorphism clonal complex in the United States. Journal of Food Protection. 81 (Supplement A): P2-229.

Interpretive Summary:

Technical Abstract: Introduction: Shiga toxin-producing Escherichia coli O26:H11 (STEC O26) has emerged as an important human pathogen capable of causing enterohemorrhagic diarrhea and hemolytic uremic syndrome (HUS). O26 strains carrying Stx2 are associated with an increased risk of HUS in comparison to strains that contain Stx1. Recently, single nucleotide polymorphism (SNP) and sequence typing (ST) of STEC O26 strains predominantly isolated from Europe revealed that Stx2 strains could be classified into one of four clonal complexes (CC), with SNP-CC1 being identified as a new European clone. Purpose: Characterize STEC O26 Stx2 SNP-CC strains in the United States. Methods: High-molecular weight DNA were used to make size-selected PacBio libraries and sequenced on a Pacific BioSciences RS II sequencing platform. Reads were assembled using HGAP v3.0 and contigs were trimmed and circularized in Geneious. Geneious, Mauve, and Virulence Finder were used to analyze the genome sequence data. Results: Strains from the United States were classified into three of the four SNP-CC previously identified for European STEC O26, and additionally into a SNP-CC that had not been previously identified. The strains from this newly identified SNP-CC differed from the other SNP-CC by integration of a Stx-phage between yfdC and argW and a large virulence plasmid that ranged from 147 to 173 kb in size. The plasmid contained the virulence factors ehxA, toxB, and espP, but was missing the catalase/peroxidase katP gene. The increased size of the plasmid could be attributed in part to the inclusion of the efa1/lifA gene, as well as 20 additional genes not previously found on the typical O26:H11 virulence plasmid. Significance: We report the identification of a new Stx2 SNP-CC in the United States. Phylogenetic analysis suggests this new SNP-CC arose through convergent evolution in STEC O26 by acquiring mobile genetic elements.