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.

The Quail Neuroretina clone 71 gene (QNR-71) is expressed during the differentiation of retinal pigmented epithelia and the epidermis. It encodes a type I transmembrane glycoprotein that shares significant sequence homologies with several melanosomal proteins. We have studied its intracellular traffic in both pigmented and non-pigmented cells. We report that a di-leucine-based sorting signal (E...

strains were negative for qnrA, qnrB and qnrS and other studies have shown that qnr in A. baumannii is not widespread. 4 Four of the eight qnr genes were found in ciprofloxacin-resistant isolates and three in isolates with intermediate susceptibility. C. freundii harboured qnrB8 and was ciprofloxacin-susceptible. Six of the eight (75%) qnr-positive isolates were ESBL-producing strains represent...

OBJECTIVES qnr genes are plasmid-mediated quinolone resistance genes. Five qnr families have been described with several alleles (7 alleles of qnrA, 53 alleles of qnrB, 1 allele of qnrC, 1 allele of qnrD and 6 alleles of qnrS). Their detection requires a PCR specific for each qnr family and further sequencing for allele characterization. METHODS High-resolution melt curve analysis (HRMA) was ...

Quinolones are potent antibacterial agents that specifically target bacterial DNA gyrase and topoisomerase IV. Widespread use of these agents has contributed to the rise of bacterial quinolone resistance. Previous studies have shown that quinolone resistance arises by mutations in chromosomal genes. Recently, a multiresistance plasmid was discovered that encodes transferable resistance to quino...

The Qnr proteins belong to the pentapeptide repeat protein family. Despite each pentapeptide repeat unit being an important structural determinant, accurately determining pentapeptide repeat units in the Qnr proteins through sequence-based alignments has been challenging. In the present study, the pentapeptide repeat units of the nine representative Qnr proteins have been precisely determined v...

qnrE1, found in a clinical Klebsiella pneumoniae isolate, was undetectable by PCR assays used for the six qnr families. qnrE1 was located on a conjugative plasmid (ca. 185 kb) and differed from qnrB alleles by 25%. Phylogenetic reconstructions of qnr genes and proteins and analysis of the qnrE1 surroundings showed that this gene belongs to a new qnr family and was likely mobilized by ISEcp1 fro...