|BAI, XIANGNING - Chinese Center For Disease Control|
|FU, SHANSHAN - Chinese Center For Disease Control|
|ZHANG, JI - Massey University|
|FAN, RUYUE - Chinese Center For Disease Control|
|XU, YANMEI - Chinese Center For Disease Control|
|SUN, HUI - Chinese Center For Disease Control|
|XU, JIANGUO - Chinese Center For Disease Control|
|XIONG, YANWEN - Chinese Center For Disease Control|
Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2018
Publication Date: 4/30/2018
Publication URL: https://handle.nal.usda.gov/10113/6472271
Citation: Bai, X., Fu, S., Zhang, J., Fan, R., Xu, Y., Sun, H., He, X., Xu, J., Xiong, Y. 2018. Identification and pathogenomic analysis of an Escherichia coli strain producing a novel Shiga toxin 2 subtype. Scientific Reports. 8:6756. https://doi.org/10.1038/s41598-018-25233-x.
Interpretive Summary: Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen that causes human gastrointestinal disease and outbreaks of diarrhea, hemorrhagic colitis and hemolytic uremic syndrome worldwide. Stxs are the primary virulence factors of STEC. In this study, we report a new subtype of Stx2, designated as Stx2h, produced by a STEC strain isolated from a healthy wild Marmota himalayana. The stx2h gene was carried on a new type of phage in a strain with mixed virulence factors from different bacterial pathotypes. The emergence of new Stx subtype and Stx-producing pathovar represents a serious problem with the tendency to cause severer disease. The novel Stx2h should be taken into account in modern strain typing and epidemiological surveillance of E. coli infections.
Technical Abstract: Shiga toxin (Stx) is the key virulent factor in Shiga toxin-producing Escherichia coli (STEC). To date, three Stx1 subtypes and Seven Stx2 subtypes have been described in E. coli, which were found to differ in receptor preference and toxin potency. Here, we identified a novel Stx2 subtype designated Stx2h in E. coli strains isolated from wild marmots in the Qinghai-Tibetan plateau, China. Stx2h shares only 91.9% nucleic acid sequence identity to the nearest Stx2 subtype. The expression of Stx2h in type strain STEC299 was inducible by mitomycin C, and culture supernatant from STEC299 was cytotoxic to Vero cells. The Stx2h converting prophage was unique in terms of insertion site, genetic composition and structure. Whole genome-based phylo- and patho-genomic analysis revealed STEC299 was closer to other pathotypes of E. coli than STEC, and possesses virulence factors from multiple pathotypes of E. coli. Our finding enlarges the pool of Stx2 subtypes and highlights the extraordinary genomic plasticity of E. coli strains. As the emergence of new Shiga toxin genotypes and new Stx-producing pathovars pose a great threaten to the public health, Stx2h should be taken into account in modern strain typing and in epidemiological surveillance of E. coli infections.