Escherichia coli and Klebsiella pneumoniae producing CTX-M cephalosporinase from swine finishing barns and their association with antimicrobial use.

We report the recovery of Escherichia coli or Klebsiella pneumoniae containing the extended-spectrum ß-lactamase gene bla(CTX-M) from 24 of 1,495 (1.6%) swine fecal samples in 8 of 50 (16%) finishing barns located in 5 U.S. states. We did not detect an association between antimicrobial use and recovery of bla(CTX-M).