Prevalence of β-lactamase and 16S rRNA methylase genes among clinical Escherichia coli isolates carrying plasmid-mediated quinolone resistance genes from animals.

Plasmid-mediated quinolone-resistance (PMQR) genes were determined by polymerase chain reactions (PCRs) in 250 Escherichia coli isolates from food-producing animals in Guangdong, China, in 2009-2010. Then, the prevalence of plasmid-mediated β-lactamase and 16S rRNA methylase genes was determined by PCRs among the PMQR-positive isolates. One hundred fifty-seven (62.