Research – Risk evaluation of E. coli ST 131 as a foodborne pathogen in Switzerland

BLV

Within recent years, the topic of multidrug-resistant, uropathogenic Escherichia coli strains has seen a rise in occurrence as foodborne pathogens. At the core of this topic is the specific clonal group referred to as Escherichia coli O25b:H4 sequence type 131 (ST 131). It is an extended-spectrum β-lactamase (ESBL) producing E. coli strain, postulated to be responsible for the spread of ESBL-encoding genes world-wide.
This literature review aimed to evaluate ST 131 as a foodborne pathogen in Switzerland, in order to assess the risk it poses for food producers in Switzerland specifically. On a global scale, ST 131 has been identified on all continents. It is mostly associated with chicken and poultry meat, and has been isolated from retail products many times.
Not exclusive to chicken, it was rarely identified from fish guts and gills. In all other meat products, ST 131 was found only in faecal matter, not in the product itself. Besides meat, the pathogen was not identified from any sources such as dairy, fruit and vegetables.
The situation is similar in Switzerland, where it was isolated frequently from chicken, rarely from fish and a complete absence of the pathogen in all other food product groups. The risk, ST 131 poses towards Swiss food producers has been evaluated as a medium risk factor for both chicken and fish products, and a low risk factor for any other products. Despite ST 131 being evaluated as a medium-to-low risk factor, depending on the product, it is still recommended to perform further research on the topic. Especially looking towards prevalence in Swiss food, in chicken and poultry meat, but also in fish.
Specifically fish designated for raw consumption (Sushi, Sashimi). Moreover, the spread of afore-mentioned ESBL-encoding genes is hypothesized to occur also during infection of humans. This leads to the recommendation, that ST 131 should be considered a food-safety risk in all products, in order to eliminate said spread. Whether this consideration as a food-safety risk is feasible, cannot be said without further analysis of products and viable treatment options.

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