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...

OBJECTIVES To gain insight into the functionality of qnr-like genes of several bacterial species of Vibrionaceae that may encode quinolone resistance determinants. METHODS A PCR-based strategy was used to obtain qnr-like genes of reference strains of Vibrio vulnificus CIP103196, Vibrio parahaemolyticus CIP71.2 and Photobacterium profundum CIP106289 that were sequenced, cloned and expressed in...

Plasmid toxins CcdB and ParE are part of addiction systems promoting plasmid maintenance. Both target host DNA gyrase, as do quinolones and plasmid-determined Qnr proteins that protect gyrase from quinolone inhibition. We cloned qnrB4, qnrS1, ccdB, parE, and the antitoxin-encoding genes ccdA and parD on compatible plasmids and tested them in combination. CcdB and ParE had no specific effect on ...

We screened 313 ceftazidime-resistant Enterobacteriaceae isolates obtained in the United States from 1999 to 2004 for all three known qnr genes. A qnr gene was present in 20% of Klebsiella pneumoniae isolates, 31% of Enterobacter sp. isolates, and 4% of Escherichia coli isolates. qnrA and qnrB occurred with equivalent frequencies and, except for qnrB in enterobacters, were stable over time. qnr...

Quinolone antibiotics have been commonly used to treat cases of multiple antibiotic resistance. Unfortunately, quinolone so much resisted by infectious bacterial agents. This study aimed evaluate the susceptibility some clinical isolates E. coli and determination plasmid-encoded resistance genes.
 Our results showed plasmid quinolone-resistance genes in following prevalence: qnr genes: S (...

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 ...

OBJECTIVE Quinolone resistance is usually caused by various chromosomal mutations, but has been more recently associated with plasmids which carry the qnr determinant. The aim of this study is to investigate the prevalence of qnr genes in clinical isolates of Enterobacteriaceae in Jamaica. METHODS A total of 255 non-duplicate fluoroquinolone-resistant Enterobacteriaceae clinical isolates, com...

Background and Objectives Since the fluoroquinolones are the broad-spectrum antibiotics, they affect both Gram-negative and Gram-positive bacteria. These antibiotics are widely prescribed by physicians. As a result, some bacteria, especially Enterobacteriaceae, have shown a resistance to this family of antibiotics. The current study aimed at detecting the frequency of qnrA, qnrB, and qnrS genes...

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 ...