RESUMO
Objective To characterize the prevalence of plasmid-mediated quinolone resistance determinants qnrA in extended-spectrum β-lactamase(ESBL)-producing Escherichia coli and Klebsiella pneumonia.Methods PCR was used to amplify qnrA gene in ESBL-rpoducing isolates(including 263isolates of Escherichia coli and 99 isolates of Klebsiella pneumonia).Conjugation experiments and southern blot hybridization were employed to definitude the location of the genes in ZJ96 isolate of Klebsiella pneumonia which had positive qnrA and CTX-M genes.Shot gun sequencing was performed for analyzing the complete nucleotide sequence of pKP96,a plasmid containing qnrA and CTX-M-24 genes in ZJ96 isolate.Results qnrA was detected in 5 out of 263(1.9%)Escherichia coli isolates and 8 out of 99(8.1%)Klebsiella pneumonia isolates.pKP96,a conjugative plasmid including qnrA gene and CTX-M-24 gene presented in ZJ96 isolate.The sequence of the plasmid pKP96 displayed the qnrA,CTX-M-24,aac(6')-Ib-cr,tetA and int Ⅰ 1 genes.Conclusion The plasmid-mediated genes,such as qnrA and CTX-M,may facilitate the prevalence of multi-drug resistant strains.