First Characterization of CTX-M-15-Producing Escherichia coli Strains Belonging to Sequence Type (ST) 410, ST224, and ST1284 from Commercial Swine in South America

We report for the first time the isolation of CTX-M-15-producing Escherichia coli strains belonging to sequence type (ST) 410, ST224, and ST1284 in commercial swine in Brazil. The bla(CTX-M-15) gene was located on F-::A9::B1 and C1::A9::B1 IncF-type plasmids, surrounded by a new genetic context comprising the IS26 insertion sequence truncated with the ISEcp1 element upstream of bla(CTX-M-15). These results reveal that commercial swine have become a new reservoir of CTX-M-15-producing bacteria in South America.