We determined the complete nucleotide sequences of three plasmids that encode CTX-M extended-spectrum beta-lactamases (ESBLs) in pulsed-field gel electrophoresis-defined United Kingdom variants (strains A, C, and D) of the internationally prevalent Escherichia coli O25:H4-ST131 clone. Plasmid pEK499 (strain A; 117,536 bp) was a fusion of type FII and FIA replicons and harbored the following 10 ...

The aac(6')-Ib gene is the most prevalent gene that encodes aminoglycoside-modifying enzymes and confers resistance to tobramycin, kanamycin, and amikacin. The aac(6')-Ib-cr variant gene can induce resistance against aminoglycoside and fluoroquinolone simultaneously. Two main methods, sequence analysis and the restriction enzyme method, can detect the aac(6')-Ib-cr variant in clinical strains. ...

OBJECTIVES To characterize the prevalence of plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae. METHODS qnrA, qnrB, qnrS, aac(6')-Ib-cr and ESBL-encoding genes were detected by PCR. MICs of 10 antimicrobial agents were determined by Etest. PFGE was used to investigate the clo...

Background: Plasmid mediated quinolone resistance (PMQR) has been shown to play an important role in resistance not only to quinolones, but also β-lactams and aminoglycosides. In fact, qnr genes are frequently carried along with β-lactamase determinants on the same plasmids. We studied the prevalence of qnrA, qnrB, qnrS and aac(6’)-Ib-cr genes among quinolone and cephalosporin resistant clinica...

background plasmid-mediated quinolone resistance genes (pmqr) have been shown to play not only an important role in quinolone resistance, but also resistance to other antibiotics, particularly β-lactams and aminoglycosides. these genes are mainly associated with clinical isolates of enterobacteriaceae. however, detection of pmqr genes in the community isolates can increase the dissemination rat...

background : plasmid mediated quinolone resistance (pmqr) has been shown to play an important role in resistance not only to quinolones, but also β-lactams and aminoglycosides. in fact, qnr genes are frequently carried along with β-lactamase determinants on the same plasmids. we studied the prevalence of qnra , qnrb , qnrs and aac(6’)-ib-cr genes among quinolone and cephalosporin resistant clin...

In this study, we investigated the presence of plasmid-mediated quinolone resistance (PMQR) genes among 101 ciprofloxacin-resistant urinary Escherichia coli isolates and searched for mutations in the quinolone-resistance-determining regions (QRDRs) of the DNA gyrase and topoisomerase IV genes in PMQR-carrying isolates. Eight isolates harboured the qnr and aac(6')-Ib-cr genes (3 qnrS1, 1 qnrB19 ...