background: avian pathogenic escherichia coli (apec), which is the causative agent of colibacillosis, harbors several putative virulence genes. an important trait of apec for both poultry and public health is antibiotic resistance. objectives: in the present study, some potential virulence genes of apecs isolated from northeast of iran and their resistance to the quinolones antibiotics were stu...

Although resistance to quinolones is commonly chromosomally-encoded in Enterobacteriaceae, the emergence of plasmid-mediated quinolone resistance (PMQR) has also been reported, with at least three known resistance mechanisms to date, i.e., Qnr, aminoglycoside acetyltransferase AAC(6')-Ib-cr and QepA. Qnr proteins protect target enzymes (DNA gyrase and type IV topoisomerase) from quinolone inhib...

Although plasmid-mediated quinolone resistance (PMQR) was thought not to exist before its discovery in 1998, the past decade has seen an explosion of research characterizing this phenomenon. The best-described form of PMQR is determined by the qnr group of genes. These genes, likely originating in aquatic organisms, code for pentapeptide repeat proteins. These proteins reduce susceptibility to ...

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...

Background: Avian pathogenic Escherichia coli (APEC), which is the causative agent of colibacillosis, harbors several putative virulence genes. An important trait of APEC for both poultry and public health is antibiotic resistance. Objectives: In the present study, some potential virulence genes of APECs isolated from Northeast of Iran and their resistance to the quinolones antibiotics were stu...

Quinolones are widely used in the treatment of respiratory infections, in large part because of their activity against Streptococcus pneumoniae and other commonly encountered respiratory tract pathogens. Pneumococcal isolates that are resistant to these "respiratory quinolones" have now begun to emerge. Resistance is attributable to mutations affecting the intracellular targets of these drugs, ...

BACKGROUND Quinolones are potent broad-spectrum bactericidal agents increasingly employed also in resource-limited countries. Resistance to quinolones is an increasing problem, known to be strongly associated with quinolone exposure. We report on the emergence of quinolone resistance in a very remote community in the Amazon forest, where quinolones have never been used and quinolone resistance ...

We have cloned the DNA gyrase and topoisomerase IV genes of Enterococcus faecalis to examine the actions of quinolones against E. faecalis genetically and enzymatically. We first generated levofloxacin-resistant mutants of E. faecalis by stepwise selection with increasing drug concentrations and analyzed the quinolone resistance-determining regions of gyrA and parC from the resistant mutants. I...

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Quinolones are increasingly favored over trimethoprim-sulfamethoxazole (TMP-SMX) for empirical treatment of uncomplicated urinary tract infection (UTI). This is associated with increasing resistance toward this broad-spectrum group of antibiotics. Our objective is to describe the prescribing patterns and identify determinants of the choice between TMP-SMX and quinolones for outpatient UTI treat...