Virulence and antimicrobial resistance of Shiga toxin-producing Escherichia coli from dairy goat and sheep farms in The Netherlands.

AIMS: The aim of our study was to investigate the virulence and resistance of STEC from small ruminants farms in The Netherlands. Moreover, the potential transmission of STEC between animals and humans on farms was evaluated. METHODS AND RESULTS: From 182 farms, in total, 287 unique STEC isolates were successfully recovered from animal samples. In addition, STEC was isolated from eight out of 144 human samples. The most detected serotype was O146:H21; however, among other serotypes also O26:H11, O157:H7, and O182:H25 isolates were present. Whole genome sequencing covering all human isolates and 50 of the animal isolates revealed a diversity of stx1, stx2, and eae sub-types and an additional 57 virulence factors. The assessed antimicrobial resistance phenotype, as determined by microdilution, was concordant with the genetic profiles identified by WGS. WGS also showed that three of the human isolates could be linked to an animal isolate from the same farm. CONCLUSIONS: The obtained STEC isolates showed great diversity in serotype, virulence, and resistance factors. Further analysis by WGS allowed for an in-depth assessment of the virulence and resistance factors present and to determine the relatedness of human and animal isolates.