Escherichia coli strains producing a novel Shiga toxin 2 subtype circulate in China.

Escherichia coli strains producing a novel Shiga toxin 2 subtype circulate in China. Int J Med Microbiol. 2019 Nov 09;:151377 Authors: Yang X, Bai X, Zhang J, Sun H, Fu S, Fan R, He X, Scheutz F, Matussek A, Xiong Y Abstract Shiga toxin (Stx) is the key virulence factor in Shiga toxin producing Escherichia coli (STEC), which can cause diarrhea and hemorrhagic colitis with life-threatening complications. Stx comprises two toxin types, Stx1 and Stx2. Several Stx1/Stx2 subtypes have been identified in E. coli, which are variable in sequences, toxicity and host specificity. Here, we report the identification of a novel Stx2 subtype, designated Stx2k, in E. coli strains widely detected from diarrheal patients, animals, and raw meats in China over time. Stx2k exhibits varied cytotoxicity in vitro among individual strains. The Stx2k converting prophages displayed considerable heterogeneity in terms of insertion site, genetic content and structure. Whole genome analysis revealed that the stx2k-containing strains were genetically heterogeneous with diverse serotypes, sequence types, and virulence gene profiles. The nine stx2k-containing strains formed two major phylogenetic clusters closely with strains belonging to STEC, enterotoxigenic E. coli (ETEC), and STEC/ETEC hybrid. One stx2k-containing strain harbored one plasmid-encoded heat-stable enterotoxin sta gene and two identical copies of chromosome-encoded stb gene, exhibiting STEC/ETEC hy...
Source: International Journal of Medical Microbiology - Category: Microbiology Authors: Tags: Int J Med Microbiol Source Type: research