Although quinolone resistance usually results from chromosomal mutations, recent studies indicate that quinolone resistance can also be plasmid mediated. The gene responsible, qnr, is distinct from the known quinolone resistance genes and in previous studies seemed to be restricted to Klebsiella pneumoniae and Escherichia coli isolates from the University of Alabama in Birmingham, where this re...

Quinolone resistance is caused mainly by chromosomal mutations in gram negative bacteria. In 1998, plasmid-mediated resistance to quinolones in clinical isolates was first reported in a Klebsiella pneumoniae strain. Locus qnr (quinolone resistance) was responsible of the quinolone resistance in this plasmid. qnr codes a protein whose function is protect both DNA-girase and topoisomerase IV from...

We have studied by PCR and DNA sequencing the presence of the qnrA, qnrB, qnrS, aac(6')-Ib-cr, qepA, intI1, and ISCR1 genes in 200 clinical isolates of Enterobacter cloacae (n = 153) and E. aerogenes (n = 47) consecutively collected between January 2004 and October 2005 in two hospitals located in Santander (northern Spain) and Seville (southern Spain). Mutations in the quinolone resistance-det...

Development of fluoroquinolone resistance can involve several mechanisms that include chromosomal mutations in genes ( gyrAB and parCE ) encoding the target bacterial topoisomerase enzymes, increased expression AcrAB-TolC efflux system, acquisition transmissible quinolone-resistance genes. In this study, 176 Salmonella isolates from animals with a broad range ciprofloxacin MICs were collected t...

Non-human primates (NHPs) for biomedical research are commonly infected with Shigella spp. that can cause acute dysentery or chronic episodic diarrhea. These animals are often prophylactically and clinically treated with quinolone antibiotics to eradicate these possible infections. However, chromosomally- and plasmid-mediated antibiotic resistance has become an emerging concern for species in t...

Nontyphoidal Salmonella enterica strains with a nonclassical quinolone resistance phenotype were isolated from patients returning from Thailand or Malaysia to Finland. A total of 10 isolates of seven serovars were studied in detail, all of which had reduced susceptibility (MIC > or = 0.125 microg/ml) to ciprofloxacin but were either susceptible or showed only low-level resistance (MIC < or = 32...

INTRODUCTION Plasmid-mediated quinolone resistance, which complicates treatment, has been increasingly identified in Escherichia coli isolates worldwide. The purpose of this study was to identify the plasmid-mediated qnrA and qnrB genes among the quinolone-resistant Escherichia coli isolated from urinary tract infections in Iran. METHODOLOGY A total of 140 Escherichia coli isolates were colle...

Resistance to beta-lactams and fluoroquinolones has been increasing in the treatment of urinary tract infections (UTIs), worldwide. Recent studies in Europe and the United States have demonstrated that steady increase in the rate of uropathogen’s resistance to commonly prescribed antibiotics is associated with plasmid-mediated resistance genes existence. According to the published data, acquirе...

Investigation of the Frequency Plasmid-Dependent Quinolone Resistance Genes in Klebsiella Pneumoniae, Pseudomonas Aeruginosa and Escherichia Coli Isolated from Surgical Site Infections