Abstract
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
Highlights
Bacterial resistance to quinolones is usually due to chromosomally encoded mechanisms, it can originate from plasmid-mediated genes
Several studies have demonstrated that most qnr-positive enterobacterial isolates are associated with extended spectrum βlactamases (ESBLs), including TEM, SHV, VEB, and CTX-M types, which are generally located on plasmids that are highly transferable and may harbor resistance genes to several different groups of antibiotics [4]
The aim of this study was to determine the prevalence of plasmid-mediated quinolone resistance (PMQR) genes and ESBL types in clinical urinary isolates of E. coli collected from two large teaching hospitals located in the European and Asian parts of Istanbul in Turkey
Summary
Bacterial resistance to quinolones is usually due to chromosomally encoded mechanisms, it can originate from plasmid-mediated genes. Several studies have demonstrated that most qnr-positive enterobacterial isolates are associated with extended spectrum βlactamases (ESBLs), including TEM, SHV, VEB, and CTX-M types, which are generally located on plasmids that are highly transferable and may harbor resistance genes to several different groups of antibiotics [4]. Today, many antibiotics, such as β-lactams and fluoroquinolones, which are widely prescribed by clinicians for the treatment of urinary tract E. coli infection, are in limited use
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