High percentage of resistance to ciprofloxacin and qnrB19 gene identified in urinary isolates of extended-spectrum β-lactamase–producing Escherichia coli in Madrid, Spain

The presence of qnr genes in 191 extended-spectrum β-lactamase–producing Escherichia coli from 2005, with 75% of resistance to ciprofloxacin, was evaluated. An SHV-12–producing E. coli carried qnrB19; both genes were transferred by conjugation. No qnrA- or qnrS-positive strains were detected. In addition, we identified 3 new parC mutations (S80W, E84R, and E84A).