Multidrug resistance IncC plasmid carrying bla in Shiga toxin-producing Escherichia coli ST215-H54 of ovine origin.

CMY-type β-lactamases are the most reported plasmid-mediated AmpC (pAmpC), with the CMY-2-like group being the most clinically relevant described in Escherichia coli at human-animal-environment interface. Shiga toxin-producing E. coli (STEC) lineages are zoonotic pathogens commonly reported causing serious clinical conditions in humans, including severe diarrheagenic diseases. Therefore, this study aimed to investigate a multidrug-resistant (MDR) STEC isolate (A313) recovered from a healthy sheep and carrying mobile bla, that encodes a pAmpC belonging to the CMY-2-like group. The A313 isolate exhibited a MDR profile to clinically relevant antimicrobials (i.e., cephalosporins, aminoglycosides, and fluoroquinolones), but reduced susceptibility to extended-spectrum cephalosporins and aztreonam. Besides, virulence genes (stx2, gad and iutA) were detected in A313, which belonged to ST215/CC10 and phylogenetic group A, whereas the fimH54 was identified. The bla gene and other antimicrobial resistance determinants [aph(6)-Id, aph(3″)-Ib, aac(3)-IId, aadA5, floR, tetA, sul1, and sul2], as well as genes encoding tolerance to mercury (merRTPCADE), were harbored by an IncC plasmid (named pA313-CMY-97, ~ 176 kb). A novel genetic context of bla, in which a 208-bp ISEcp1 was truncated by an IS26 in the opposite orientation upstream of the bla gene (IS26-∆ISEcp1-bla-blc-sugE-encR), was also identified in pA313-CMY-97. To the best of our knowledge, this is the first report on the acquisition of bla into a plasmid. Therefore, we reported ovine as reservoir of clinically relevant MDR bacteria carrying mobile bla with potential for zoonotic transmission.