Emergence of Escherichia coli encoding Shiga toxin 2f in human Shiga toxin-producing E. coli (STEC) infections in the Netherlands, January 2008 to December 2011

I Friesema; K van der Zwaluw; T Schuurman; M Kooistra-Smid; E Franz; Y van Duynhoven; W van Pelt

doi:10.2807/1560-7917.ES2014.19.17.20787

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Emergence of Escherichia coli encoding Shiga toxin 2f in human Shiga toxin-producing E. coli (STEC) infections in the Netherlands, January 2008 to December 2011
I Friesema¹ , K van der Zwaluw¹ , T Schuurman² , M Kooistra-Smid³ , E Franz¹ , Y van Duynhoven¹ , W van Pelt¹
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Affiliations: ¹ Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands ² Medical Microbiology, section Virology, University Medical Centre Groningen, Groningen, the Netherlands ³ Department of Research and Development, Laboratory for Infectious Diseases, Groningen, the Netherlands

Correspondence:
I Friesema
ingrid.friesema rivm.nl
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Citation style for this article: Friesema I, van der Zwaluw K, Schuurman T, Kooistra-Smid M, Franz E, van Duynhoven Y, van Pelt W. Emergence of Escherichia coli encoding Shiga toxin 2f in human Shiga toxin-producing E. coli (STEC) infections in the Netherlands, January 2008 to December 2011. Euro Surveill. 2014;19(17):pii=20787. https://doi.org/10.2807/1560-7917.ES2014.19.17.20787 Received: 18 Mar 2013

Abstract

The Shiga toxins of Shiga toxin-producing Escherichia coli (STEC) can be divided into Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) with several sub-variants. Variant Stx2f is one of the latest described, but has been rarely associated with symptomatic human infections. In the enhanced STEC surveillance in the Netherlands, 198 STEC O157 cases and 351 STEC non-O157 cases, including 87 stx2f STEC isolates, were reported between 2008 and 2011. Most stx2f strains belonged to the serogroups O63:H6 (n=47, 54%), O113:H6 (n=12, 14%) and O125:H6 (n=12, 14%). Of the 87 stx2f isolates, 84 (97%) harboured the E. coli attaching and effacing (eae) gene, but not the enterohaemorrhagic E. coli haemolysin (hly) gene. Stx2f STEC infections show milder symptoms and a less severe clinical course than STEC O157 infections. Almost all infections with stx2f (n=83, 95%) occurred between June and December, compared to 170/198 (86%) of STEC O157 and 173/264 (66%) of other STEC non-O157. Stx2f STEC infections in the Netherlands are more common than anticipated, and form a distinct group within STEC with regard to virulence genes and the relatively mild disease.