Shiga toxin producing E. coli (STEC) is a foodborne pathogen which causes severe, debilitating, and sometimes fatal, illness. Ireland consistently has one of the highest incidence rates of human STEC infection in Europe. Cattle are one of the primary reservoirs for STEC, excreting the pathogen in their faeces. The amount of pathogen excreted varies greatly, with animals shedding >log104 c.f.u. g faeces being termed ‘super-shedders’. Human infection can occur from faecal contamination of meat, dairy, fresh produce or drinking water. STEC can survive for extended periods in soil, slurry and water, although the exact means is unknown. The objective of this study was to examine phenotypic traits potentially relevant to extended environmental survival in two strain banks: (1) clinical and bovine STEC, in comparison with non-STEC, isolated from the production environment and (2) E. coli O157:H7 of known shedding status. The strain banks were assessed for biofilm-forming abilities and the ability to adhere to the muscle component collagen-I, using a 96-well crystal violet assay, where the absorbance of bound cells indicated biofilm formation levels or adherence to collagen. Extracellular components involved in attachment were assessed using Congo red agar and pellicle formation was also examined. Phenotypic traits potentially related to extended environmental persistence were observed more frequently in non-STEC. However, these traits were also observed in some STEC isolates, showing phenotype is strain dependent indicating a risk for enhanced environmental survival of some STEC isolates. The shedding status of E. coli O157:H7 is not dictated by the investigated characteristics alone.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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