Survey on the genes conferring plasmid-mediated quinolone resistance and those encoding β-lactamases in Escherichia coli isolates / 中国感染与化疗杂志

ABSTRACT

Objective To examine the prevalence of plasmid mediated quinolone resistance (PMQR) genes and their correlation with the genes encoding β-lactamases in E.coli isolates.Methods A total of 200 levofloxacin-and/or ciprofloxacin-resistant E.coli isolates were collected from Fujian Medical University Union Hospital during the period from July to December 2013.PCR method was used to screen these E.coli isolates for the presence of qnrA,qnrB,qnrC,qnrD,qnrS,aac(6')-Ib-cr,qepA,oqxAB genes,and the blaTEM,blasnv and blacTx-M genes in the PMQR positive strains.Agar dilution method was utilized to measure the antimicrobial susceptibility of PMQR-positive strains.Phylogenetic analysis was conducted by triplex PCR.Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) was used to evaluate the genetic similarity between the PMQR-positive isolates.Results Of the 200 clinical isolates of E.coli,58 (29.0％)were PMQR-positive.And qnr,aac(6')-Ib-cr,oqxAB,and qepA genes were positive in 11 (5.5％),41 (20.5％),16 (8.0％),1 (0.5％) strains,respectively.The genes encoding CTX-M-1,CTX-M-9 and TEM type enzymes was positive in 32 (55.2％),17 (29.3％),and 1 (1.7％) of the PMQR-positive strains,respectively.The blasHv gene was not identified in any isolate.PMQR-positive strains were multi-drug resistant.Phylogenetic analysis indicated that 21 (36.2％),17 (29.3％),11 (19.0％),and 9 (15.5％) of the PMQR-positive strains belonged to group A,group D,group B2 and group B 1,respectively.ERIC-PCR suggested the PMQR-positive isolates belonged to 50 different types.Only one strain was non-typeable.Conclusions Most of the PMQR-related genes in E.coli are aac(6')-Ib-cr,qnr,and oqxAB in our hospital,which are highly relevant to β-1actamase genes.PMQR-positive strains may spread by way of non-clonal dissemination in our hospital.