Location: Produce Safety and Microbiology ResearchTitle: Is Shiga toxin-producing Escherichia coli O45 no longer a food safety threat? The danger is still out there
|ZHANG, YUJIE - Shanghai Ocean University|
|SUN, XIAOHONG - Shanghai Ocean University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2020
Publication Date: 4/2/2020
Citation: Zhang, Y., Liao, Y., Salvador, A., Sun, X., Wu, V.C. 2020. Is Shiga toxin-producing Escherichia coli O45 no longer a food safety threat? The danger is still out there [abstract]. Meeting Abstract.
Technical Abstract: Shiga toxin-producing Escherichia coli O157 and top 6 non-O157 strains have been frequently associated with foodborne outbreaks; however, in the last decades, CDC only reported four STEC O45-associated outbreaks in the United States. The information regarding the genomic characterization of STEC O45 that can be used to reveal the evolutionary trait of this particular serogroup is scarce. Thus, the objectives of this study were to genomically characterize four O45 STEC strains and to determine their pathogenicity and evolutionary relatedness with other pathogenic STEC strains. Three environmental E. coli O45:H16 strains (RM11911, RM13745, and RM13752) and one clinical E. coli O45:H2 strain (SJ7) were used in the study. The whole-genome sequencing of these strains was performed using PacBio Sequel II and further assembled by Flye2. Subsequently, comparative genomic analyses were conducted to evaluate the pathogenicity elements and evolutionary relatedness by comparing O45 strains to other notorious pathogens with different serotypes. Results showed that the four STEC O45 strains had genome sizes ranging from 5.2 to 5.4-Mbp with one or two plasmids. The profiles of prophages and genomic islands of three environmental E. coli O45:H16 strains, particularly associated with the virulence factors, were significantly different from those present in the clinical O45:H2 strain. Additionally, the phylogenetic analysis showed that the clinical strain E. coli O45:H2 was more closely related to O103:H2 clinical strains than to E. coli O45:H16 and other selected clinical STEC strains. Furthermore, E. coli O45:H2 contained the virulence genes, including stx1, eae, and LEE islands, locating on different prophages and genomic islands, similar to those found in the clinical E. coli O103:H2 strains. The findings of this study provide genomic evidence, indicating that E. coli O45:H2 and O103:H2 are evolving from a common lineage and should be further included in epidemiological surveillance due to potential threats to the public health.