Research – Sporadic Occurrence of Enteroaggregative Shiga Toxin–Producing Escherichia coli O104:H4 Similar to 2011 Outbreak Strain


We describe the recent detection of 3 Shiga toxin–producing enteroaggregative Escherichia coli O104:H4 isolates from patients and 1 from pork in the Netherlands that were genetically highly similar to isolates from the 2011 large-scale outbreak in Europe. Our findings stress the importance of safeguarding food supply production chains to prevent future outbreaks.

Shiga toxin–producing Escherichia coli (STEC) is a zoonotic pathogen that causes illness ranging from mild diarrhea to haemolytic uremic syndrome and death. During 2011, an exceptionally large outbreak caused by serotype O104:H4 STEC occurred in Europe, mainly in Germany and France, that was associated with sprouts grown from imported fenugreek seeds (1). Besides the ability to produce Shiga toxin, specifically stx2a, the strain had the genetic characteristics and phylogenetic backbone of an enteroaggregative E. coli (EAEC) pathotype (2) but lacked other classical STEC virulence markers eae and hlyA (3). In addition, the outbreak strain carried plasmid-borne blaCTX-M-15 and blaTEM-1 genes. The epidemiologic investigation revealed that a contaminated batch of fenugreek seeds imported into the European Union from Egypt was the most probable source of the pathogen causing the outbreak (4).

After the 2011 outbreak in Germany and France, only a few sporadic cases of infection with Shiga toxin–producing EAEC O104:H4 were reported, most related to travel to Turkey or North Africa (5–8). We describe the sporadic occurrence of Shiga toxin–producing EAEC O104:H4 isolates in the Netherlands, originating from 2 clinical cases from 2019 and 2020 and 1 food isolate from 2017. In addition, we report a clinical case from Austria in 2021.

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