Location: Produce Safety and Microbiology ResearchTitle: Complete genome sequences of two Escherichia coli O145:H28 outbreak strains of food origin) Author
Submitted to: Genome Announcements
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2014
Publication Date: 5/22/2014
Citation: Cooper, K.K., Mandrell, R.E., Louie, J.W., Korlach, J., Clark, T.A., Parker, C., Huynh, S., Chain, P.S., Ahmed, S., Carter, M.Q. 2014. Complete genome sequences of two Escherichia coli O145:H28 outbreak strains of food origin. Genome Announcements. 2(3):e00482-14. DOI: 10.1128/genomeA.00482-14.. Interpretive Summary: We determined the complete genome sequences of two E. coli O145 strains isolated from food samples. Strain RM12581 is linked to a 2010 US lettuce-associated outbreak and strain RM12761 is linked to a 2007 Belgium ice-cream-associated outbreak. The genomic information obtained in this study facilitates the discovery of genetic markers for detection of enterohemorrhagic Escherichia coli in food and in agricultural environments. Furthermore, comparative genomics analyses of two sequenced O145 strains with their corresponding clinical isolates and other EHEC genomes provide evidences on the important factors contributing to the emergence of this important group of foodborne pathogens.
Technical Abstract: Although serotype O157:H7 is the predominant enterohemorrhagic Escherichia coli (EHEC), outbreaks of non-O157 EHEC that cause severe foodborne illness, including hemolytic uremic syndrome have increased worldwide. O145 is recognized as one of the six non-O157 serotypes that are most frequently associated with human disease in the US. We determined the complete genome sequences of two E. coli O145:H28 outbreak strains of food origin. Strain RM12581 was isolated from bagged romaine lettuce during a 2010 US lettuce-associated outbreak. E. coli O145:H28 strain RM12761 was isolated from ice cream during a 2007 ice cream-associated outbreak in Belgium. We then compared with the genome of each food isolate with the corresponding clinical isolate we sequenced previously (BMC Genomics 15:17). A total of 18 SNPs were identified in non-repeat regions for the 2007 Belgian ice cream-associated outbreak strains, of which, 11 are in intergenic regions and seven are in coding regions (4 synonymous, 2 nonsense mutations, and 1 nonsynonymous mutation). The two CDSs with a nonsense mutation are an endonuclease (ECRM13516_0820) and a hypothetical protein (ECRM13516_2566). The nonsynonymous mutation was detected in the gene encoding a valyl-tRNA synthetase (ECRM13516_5090). In contrast, no SNPs were identified in non-repeat regions between the two strains linked to the 2010 US lettuce-associated outbreak. A nearly identical methylome was detected between the two E. coli O145 strains of food and clinical origin that were linked to the same outbreak.