Plasmid-Mediated Quinolone Resistance Genes in Escherichia coli Urinary Isolates from Two Teaching Hospitals in Turkey: Coexistence of TEM, SHV, CTX-M and VEB-1 Type β-lactamases
Purpose: To evaluate the occurrence of plasmid-mediated quinolone resistance (PMQR) genes and the prevalence of extended spectrum β-lactamase (ESBL) types in Escherichia coli clinical isolates. Methods: Sixty-one ESBL-producing urinary E. coli isolates were studied. An antibiotic susceptibility test was performed using the disc diffusion method. ESBL production was determined using a double-disc synergy test for all isolates; E-test and Vitek 2 were used for plasmid-mediated quinolone resistance (PMQR)-positive isolates and their transconjugants. The presence of PMQR and β-lactamase genes was determined by polymerase chain reaction (PCR). Results: The strains displayed high rates of resistance to norfloxacin (80 %). The most frequent PMQR gene was aac(6’)-Ib-cr (45.9 %). In all, one qnrA1 (1.6 %), one qnrS1 (1.6 %), and two qepA1-positive isolates (5.7 %) were identified. The genes, qnrS1+aac(6’)-Ib-cr and qepA1, were co-expressed with blaCTX-M-15 gene, while qnrA1 occurred with blaTEM-1, blaSHV, and blaVEB-1 genes. The most frequent β-lactamase type was cefotaximase (CTX-M), which generally hydrolyzes cefotaxime (92 %) more than it does ceftazidime; followed by temoneira (TEM, 39 %); sulfhydryl variable (SHV, 5 %), and Vietnamese extended-spectrum beta–lactamase (VEB, 1.6 %).
Conclusion: A high prevalence of aac(6’)-Ib-cr and CTX-M type β-lactamase was detected in ESBLproducing E. coli strains. This study also identified the co-expression of qnrA1 and blaVEB-1 genes and of qnrS1+aac(6’)-Ib-cr in E. coli isolates. The co-existence of PMQR genes with ESBLs may lead to a serious public health problem.
Keywords: β-lactamase, Quinolone resistance, aac(6’)-Ib-cr, CTX-M-15, VEB-1