The goal of this study was to compare the molecular features of bovine- and human community-acquired extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in Israel. Bovine ESBL-producing E. coli were isolated during a point-prevalence study from the main farming locations throughout Israel. Human ESBL-producing E. coli isolates were collected from community-acquired urinary tract infection cases. Molecular typing was done initially by repetitive extragenic palindromic-PCR. Representative isolates were subjected to next-generation sequencing (NGS) and analyzed for multilocus sequence typing (MLST), core genome MLST (cgMLST), blaCTX-M gene allele, and mobile genetic elements (MGEs) surrounding it. Out of the 287 bovine- and 104 community-derived ESBL-producing E. coli isolates, 44 and 26 isolates were subjected to NGS, respectively. Both populations exhibited a diverse but distinct clonal structure with predominance of several sequence types (STs); two clones, ST-10/167 (n = 13) and ST-38 (n = 8), were present. cgMLST analysis of these clones revealed that the majority of isolates exhibited phylogenetic distance (PD) of >178 gene difference from their closest isolate, with the exception of five isolates that exhibited PD of <24 gene difference, including two bovine- to three community-derived isolates. Hence, clonal transmission of ESBL-producing E. coli between cattle and the community, although uncommon, is likely to have occurred. The blaCTX-M-15 gene was identified in 52/70 (74%) isolates from both cattle and the community and was surrounded by MGEs that were composed mostly of either the Tn3 or IS1380 families. Thus, MGEs are likely to play an important role in the exchange of resistance genes.
Keywords: ESBL; horizontal gene transfer; livestock–human transmission.