Genetic characterization of Shiga toxin producing Escherichia coli belonging to the emerging hybrid pathotype O80:H2 isolated from humans 2010-2017 in Switzerland

Shiga toxin-producing E. coli (STEC) O80:H2 is an uncommon hybrid pathotype that has recently emerged in France. We analysed 18 STEC O80:H2 isolated from humans in Switzerland during 2010-2017. All isolates carried stx2a or stx2d, the rare eae variant eae-ξ and at least seven virulence genes associated with pS88, a plasmid that is found in extraintestinal pathogenic E. coli (ExPEC). Whole genome sequencing (WGS) identified additional chromosomal extraintestinal virulence genes encoding for type 1 fimbria (fimA, fimC and fimH), aerobactin (iuc/iutA) and afimbrial adhesins (afaA/C/D/E-VIII). Core genome multi-locus sequence typing (cgMLST) detected two closely related but distinct subclusters with different stx2 and iuc/iutA genotypes. All isolates were multidrug resistant (MDR), but susceptible to third generation cephalosporins and azithromycin. STEC/ExPEC hybrid pathotypes such as STEC O80:H2 represent a therapeutical challenge in the event of extraintestinal infection.