Pathogenicity assessment of Shiga toxin‐producing Escherichia coli (STEC) and the public health risk posed by contamination of food with STEC

Abstract

The provisional molecular approach, proposed by EFSA in 2013, for the pathogenicity assessment of Shiga toxin-producing Escherichia coli (STEC) has been reviewed. Analysis of the confirmed reported human STEC infections in the EU/EEA (2012-2017) demonstrated that isolates positive for any of the reported Shiga toxin (Stx) subtypes (and encoding stx gene subtypes) may be associated with severe illness (defined as bloody diarrhoea (BD), haemolytic uraemic syndrome (HUS) and/or hospitalisation). Although strains positive for stx2a gene showed the highest rates, strains with all other stx subtypes, or combinations thereof, were also associated with at least one human case with a severe clinical outcome. Serogroup cannot be used as a predictor of clinical outcome and the presence of the intimin gene (eae) is not essential for severe illness. These findings are supported by the published literature, a review of which suggested there was no single or combination of virulence markers associated exclusively with severe illness. Based on available evidence, it was concluded that all STEC strains are pathogenic in humans, capable of causing at least diarrhoea and that all STEC subtypes may be associated with severe illness. Source attribution analysis, based on 'strong evidence' outbreak data in the EU/EEA (2012-2017), suggests that 'bovine meat and products thereof', 'milk and dairy products', 'tap water including well water' and 'vegetables, fruit and products thereof' are the main sources of STEC infections in the EU/EEA, but a ranking between these categories cannot be made as the data are insufficient. Other food commodities are also potentially associated with STEC infections but rank lower. Data gaps are identified, and are primarily caused by the lack of harmonisation in sampling strategies, sampling methods, detection and characterisation methods, data collation and reporting within the EU. (VTEC). All these institutions provided data for this scientific output in the context of two consultations developed via the EU survey tool (Appendices I and J).

Investigation on the Evolution of Shiga Toxin-Converting Phages Based on Whole Genome Sequencing

“…Interestingly, the STEC strains that carry the phages conveying the subtypes Stx2a, Stx2c and Stx2d are also those most often linked to severe disease, during human infection (Koutsoumanis et al, 2020). Additional to the advantage offered to the E. coli in the ruminants' gastro-intestinal (GI) tract, the nanS-p could also cause, as a side effect, an improved colonization of the human GI tract, rich of Neu-5,9-Ac 2 (Saile et al, 2018), facilitating the insurgence of the most severe forms of the infections in humans.…”

Quantitative risk assessment of haemolytic uremic syndrome associated with beef consumption in Argentina

“…Haemolytic-uremic syndrome is considered a multifactorial disease [18] and, for this reason, HUS endemicity in Argentina cannot be explained only by beef consumption. Although the consumption of raw beef, raw milk, lettuce, sprouts, fruit juices and vegetables is recognized as a potential source of STEC infection in human beings [137], environmental exposure, direct contact with animals and person-to-person transmission have also been identified as important risk factors [18,[138][139][140][141]. In Argentina, information on potential food sources and transmission routes other than beef is scarce.…”

The Role of Essential Oils against Pathogenic Escherichia coli in Food Products

“…Increased the expression of stx1A and stx2A at 0.03%; down-regulation of stx1A and stx2A on ground beef. The encapsulation of EO have shown promising effects regarding the protection against the expression of virulence-related genes [3]. This approach was evaluated with Zataria multiflora EO on the expression of stx2A.…”

“…Among the main foodborne pathogens, Escherichia coli have been standing out due to recurrent outbreaks every year. Some of the food products related to this pathogenic bacterium are clove sprouts, ground bison meat, chicken salad, beef patties, raw milk cheese, and seafood sauce [2,3].…”