We determined the prevalence of plasmid-mediated quinolone resistance mechanisms among non-Typhi Salmonella spp. isolated from humans, food animals, and retail meat in the United States in 2007. Six isolates collected from humans harbored aac(6')Ib-cr or a qnr gene. Most prevalent was qnrS1. No animal or retail meat isolates harbored a plasmid-mediated mechanism.

Inappropriate use of antibiotics in clinical settings is thought to have led to the global emergence and spread of multidrug-resistant pathogens. The goal of this study was to investigate the prevalence of genes encoding aminoglycoside resistance and plasmid-mediated quinolone resistance among clinical isolates of Klebsiella pneumoniae. All K. pneumoniae isolates were phenotypically identified ...

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 ...

PURPOSE Extended spectrum beta-lactamases (ESBLs) are cephalosporinases that confer resistance to a wide variety of oxyimino cephalosporins and create serious therapeutic problems. In addition, the quinolone resistance qnr genes are becoming increasingly prevalent in clinical isolates, some of which also produce ESBL. This study was designed to evaluate the occurrence and genotypic distribution...

Ninety-three Malaysian extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolates were investigated for ciprofloxacin resistance. Two mismatch amplification mutation (MAMA) assays were developed and used to facilitate rapid detection of gyrA and parC mutations. The isolates were also screened for plasmid-mediated quinolone resistance (PMQR) genes including aac(6')-Ib-cr, qepA...

Quinolone resistance in members of the Enterobacteriaceae family is mostly due to mutations in the quinolone resistance-determining regions of topoisomerase genes. CTX-M-22 is a member of the CTX-M family which can reduce extended-spectrum β-lactamase (ESBL) production and modulate antibiotic resistance, resulting in low ceftazidime minimum inhibitory concentrations (MICs). There are four diffe...

Three major groups of the plasmid-mediated quinolone resistance (Qnr) determinants have been identified so far in Enterobacteriaceae: the QnrA group, which includes 6 variants, the QnrB group, which includes 19 variants, and the QnrS group, which includes 3 variants (5). Although Qnr proteins produce only low-level resistance, they provide a favorable background for higher resistance to occur a...

1. Jacoby GA, Gacharna N, Black TA et al. Temporal appearance of plasmid-mediated quinolone resistance genes. Antimicrob Agents Chemother 2009; 53: 1665–6. 2. Robicsek A, Jacoby GA, Hooper DC. The worldwide emergence of plasmid-mediated quinolone resistance. Lancet Infect Dis 2006; 6: 629–40. 3. Torpdahl M, Hammerum AM, Zachariasen C et al. Detection of qnr genes in Salmonella isolated from hum...