Genomic analysis of Shiga toxin-producing Escherichia coli O157:H7 from cattle and pork-production related environments
Citation
Zhang, P., Essendoubi, S., Keenliside, J., Reuter, T., Stanford, K., King, R., Lu, P., Yang, X. (2021). Genomic analysis of Shiga toxin-producing Escherichia coli O157:H7 from cattle and pork-production related environments. npj Science of Food, [online] 5(1), http://dx.doi.org/10.1038/s41538-021-00097-0
Plain language summary
Pork in general is not a common food vehicle for transmitting E. coli O157, a serious human pathogen. Three E. coli O157:H7 outbreaks have been attributed to contaminated pork in Alberta, Canada, recently. This study investigates the phylogenetic relatedness of E. coli O157:H7 from pigs, cattle, and pork-production environments for source attribution. Limited strain diversity was observed using five conventional subtyping methods, with most or all strains being in one subgroup. Whole-genome single nucleotide polymorphism analysis confirmed the recent ancestry of the isolates from all three sources. Most environmental isolates clustered closer with pig isolates than cattle isolates. Also, a direct link was observed between 2018-outbreak environmental isolates and isolates collected from a pig farm in 2018. The results show some E. coli O157:H7 strains could establish persistence on pig farms, and can contaminate pork and pig production related environments.
Abstract
Three E. coli O157:H7 outbreaks have been attributed to contaminated pork in Alberta, Canada, recently. This study investigates the phylogenetic relatedness of E. coli O157:H7 from pigs, cattle, and pork-production environments for source attribution. Limited strain diversity was observed using five conventional subtyping methods, with most or all strains being in one subgroup. Whole-genome single nucleotide polymorphism analysis confirmed the recent ancestry of the isolates from all three sources. Most environmental isolates clustered closer with pig isolates than cattle isolates. Also, a direct link was observed between 2018-outbreak environmental isolates and isolates collected from a pig farm in 2018. The majority of pig isolates harbor only one Shiga toxin gene, stx2a, while 70% (35/50) of the cattle isolates have both stx1a and stx2a. The results show some E. coli O157:H7 strains could establish persistence on pig farms and as such, pigs can be a significant source of the organism.