Characteristics of Clinical Shiga Toxin-Producing Escherichia coli Isolated from British Columbia

Abstract EN

Shiga toxin-producing Escherichia coli (STEC) are significant public health threats.

Although STEC O157 are recognized foodborne pathogens, non-O157 STEC are also important causes of human disease.

We characterized 10 O157:H7 and 15 non-O157 clinical STEC derived from British Columbia (BC).

Eae, hlyA, and stx were more frequently observed in STEC O157, and 80 and 100% of isolates possessed stx1 and stx2, respectively.

In contrast, stx1 and stx2 occurred in 80 and 40% of non-O157 STEC, respectively.

Comparative genomic fingerprinting (CGF) revealed three distinct clusters (C).

STEC O157 was identified as lineage I (LI; LSPA-6 111111) and clustered as a single group (C1).

The cdi gene previously observed only in LII was seen in two LI O157 isolates.

CGF C2 strains consisted of diverse non-O157 STEC while C3 included only O103:H25, O118, and O165 serogroup isolates.

With the exception of O121 and O165 isolates which were similar in virulence gene complement to STEC O157, C1 O157 STEC produced more Stx2 than non-O157 STEC.

Antimicrobial resistance (AMR) screening revealed resistance or reduced sensitivity in all strains, with higher levels occurring in non-O157 STEC.

One STEC O157 isolate possessed a mobile blaCMY-2 gene transferrable across genre via conjugation.