Public health risks associated with Enteroaggregative Escherichia coli (EAEC) as a food-borne pathogen
Enteroaggregative Escherichia coli (EAEC) adhere to tissue culture cells in a stacked-brick pattern mediated by aggregative adherence fimbriae (AAF). EAEC strains often produce the heat-stable toxin EAST1, the Shigella enterotoxin (ShET1) and Haemolysin E. EAEC have been associated with cases of diarrhoea in travellers, children and immunocompromised patients and with urinary tract infections. Shiga toxin (Stx)-producing EAEC have been associated with Haemolytic Uraemic Syndrome and Haemorrhagic Colitis. EAEC are considered to be adapted to humans. In low-income countries animals may become exposed to EAEC from human waste. Food-related outbreaks of EAEC are frequently suggestive of cross-contamination by asympomatic food handlers. EAEC form biofilms, which has been linked to the severity of disease. The adhesion assay remains the most sensitive option for confirming isolates as EAEC. PCR provides accurate identification of EAEC and diagnosis of EAEC infections, but there is no consensus on a standard assay for the examination of foods. The protocol of the European Union Reference Laboratory for E. coli including Verocytotoxin-producing E. coli (EU RL VTEC) is considered a good candidate for the molecular detection of EAEC in food matrices by EU MSs. Whole genome sequencing (WGS) can provide data on the population structure of EAEC. Foodborne outbreaks of EAEC exhibiting antimicrobial resistance (AMR) have been reported but the origin of the resistance genes has not been fully established. Research needs include: (i) the development and validation of PCR-based methods for detection and quantification of EAEC in foods, and (ii) a standardised and validated multiplex approach to the identification of causal agents of diarrhoeal illnesses involving multiple pathogens. Surveillance needs include: (i) quantification of the possible involvement of EAEC strains in foods originating from low-income countries where sanitation is poor, and (ii) increased surveillance of foods associated with mixed pathogen outbreaks. When investigating foodborne outbreaks, testing for EAEC should be included as routine. Finally, WGS-based approaches for EAEC should be further explored.