Fluoroquinolones are poorly active against enterococci. Recently, plasmid-borne resistance to fluoroquinolones due to the qnr gene was reported in members of the Enterobacteriaceae family. The gene encodes a pentapeptide repeat protein that protects DNA gyrase from inhibition by fluoroquinolones. We have identified in the genome of Enterococcus faecalis V583 a qnr-like gene, named E. faecalis q...

Although quinolone resistance commonly results from chromosomal mutation, recent studies indicate that such resistance can also be transferred on plasmids carrying the gene responsible, qnr. One hundred ten ciprofloxacin-resistant clinical isolates of Klebsiella pneumoniae and Escherichia coli from the United States were screened for the qnr gene by PCR and Southern hybridization of plasmid DNA...

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...

OBJECTIVES The aims of this study were to identify qnr genes among quinolone-resistant Escherichia coli isolates from defined disease conditions of companion and farm animals obtained in the BfT-GermVet study, and to gain insight into their localization and the organization of the qnr gene regions. METHODS The qnr genes were detected by PCR and confirmed by sequencing. qnr-positive isolates w...

Proper growth and development of multicellular organisms requires precise regulation of developmental genes. One aspect of this regulation is at the level of transcription from the gene promoters. As an initial approach to understanding the regulation of the Pax-6 gene, which plays an important role in eye development and perhaps in other developmental processes, we characterized a promoter reg...

Quinolone resistance normally arises by mutations in the chromosomal genes for type II topoisomerases and by changes in the expression of proteins that control the accumulation of quinolones inside bacteria. A novel mechanism of plasmid-mediated quinolone resistance was recently reported that involves DNA gyrase protection by a pentapeptide repeat family member called Qnr. This family includes ...

BACKGROUND We investigated the prevalence of plasmid-mediated quinolone resistance and its association with extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase in Enterobacteriaceae. METHODS A total of 347 non-duplicated isolates of Enterobacteriaceae were collected between August and October 2006 from 2 hospitals. Qnr determinant screening was conducted using PCR amplification, a...

OBJECTIVES Plasmid-mediated quinolone resistance (PMQR) caused by qnr genes has been known for 15 years. Information about global distribution and prevalence of qnr genes is abundant, but clinical information concerning infections produced by these isolates and risk factors for their acquisition is limited. METHODS Klebsiella pneumoniae blood isolates (n = 227) from a 1 year prospective cohor...

BACKGROUND AND OBJECTIVES The ciprofloxacin resistance of Klebsiella (K.) pneumoniae is mediated primarily through alterations in type II topoisomerase (gyrA) gene and plasmid-mediated quinolone resistance-conferring genes (qnr). This study aimed to define the prevalence of plasmid-mediated quinolone resistance-conferring genes (qnr) and type II topoisomerase (gyrA) alterations of a population ...

Seven hundred fifty-one Escherichia coli clinical isolates collected from 140 Japanese hospitals between 2002 and 2006 were screened for the qepA and qnr genes. Two E. coli isolates (0.3%) harbored qepA, but no qnr was identified. The results suggested a low prevalence of E. coli harboring qepA or qnr in Japan.