Mechanisms of Chromosome and Plasmid-mediated Quinolones Resistance in Escherichia coli Strains Isolated from ICU / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To study the mechanisms of chromosome and plasmid-mediated quinolones resistance in Escherichia coli(ECO).METHODS Clinical isolates of ECO were collected from clinical specimens at ICU of Yinzhou People′s Hospital from Dec 2007 to Jun 2008.To detect the susceptibility to 30 types of antibiotics K-B disk diffusion method was used.The susceptibicity to ciprofloxacin and levofloxacin were detected by agar dilution testing.Then six type genes gyrA,qnrA,qnrB,qnrS,aac(6′)-Ⅰb-Cr,and qepA were investigated by PCR.In the meantime,the PCR products were sequenced.RESULTS The alterations in gyrA were found in all 20 tested strains.Two new subtypes were found in ECO 13 and ECO 15.Three strains were found acc(6′)-Ⅰb-Cr and ECO 2 was detected qurA gene.CONCLUSIONS The mutations in gyrA play a dominant role in the resistance to quinolones in ECO.Both aac(6′)-Ⅰb-Cr and qepA may responsible for quinolones resistance in ECO too.