September 22, 2019  |  

Genomic characterization of ß-glucuronidase-positive Escherichia coli O157:H7 producing Stx2a.

Authors: Ogura, Yoshitoshi and Seto, Kazuko and Morimoto, Yo and Nakamura, Keiji and Sato, Mitsuhiko P and Gotoh, Yasuhiro and Itoh, Takehiko and Toyoda, Atsushi and Ohnishi, Makoto and Hayashi, Tetsuya

Among Shiga toxin (Stx)-producing Escherichia coli (STEC) O157:H7 strains, those producing Stx2a cause more severe diseases. Atypical STEC O157:H7 strains showing a ß-glucuronidase-positive phenotype (GP STEC O157:H7) have rarely been isolated from humans, mostly from persons with asymptomatic or mild infections; Stx2a-producing strains have not been reported. We isolated, from a patient with bloody diarrhea, a GP STEC O157:H7 strain (PV15-279) that produces Stx2a in addition to Stx1a and Stx2c. Genomic comparison with other STEC O157 strains revealed that PV15-279 recently emerged from the stx1a/stx2c-positive GP STEC O157:H7 clone circulating in Japan. Major virulence genes are shared between typical (ß-glucuronidase-negative) and GP STEC O157:H7 strains, and the Stx2-producing ability of PV15-279 is comparable to that of typical STEC O157:H7 strains; therefore, PV15-279 presents a virulence potential similar to that of typical STEC O157:H7. This study reveals the importance of GP O157:H7 as a source of highly pathogenic STEC clones.

Journal: Emerging infectious diseases
DOI: 10.3201/eid2412.180404
Year: 2018

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