Objective: Although quinolone resistance results mostly from chromosomal mutations in Klebsiella pneumoniae, it may also be mediated by plasmid – encoded qnr determinants. Plasmid-mediated quinolone resistance (PMQR) was increasingly identified in Enterobacteriaceae family worldwide. The aim of this study was to investigate the prevalence of qnr genes in clinical isolates of Klebsiella pn...

In the title mol-ecule, C(16)H(9)NO(5)S, there is an intra-molecular O-H⋯O hydrogen bond involving the quinolone carbonyl O atom and a carboxyl OH group. In the crystal, inter-molecular O-H⋯O hydrogen bonds between the carbonyl group of the quinolone carboxyl group, and a second carboxyl group on the thia-zeto moiety lead to the formation of chains propagating along [201] and perpendicular to t...

Until recently, Salmonella enterica serotype Enteritidis has remained sensitive to most antibiotics. However, national surveillance data from Denmark show that quinolone resistance in S. Enteritidis has increased from 0.8% in 1995 to 8.5% in 2000. These data support concerns that the current use of quinolone in food animals leads to increasing resistance in S. Enteritidis and that action should...

High quinolone resistance rates were observed among oxyiminocephalosporin-resistant enterobacteria. In the present study, we searched for the prevalence of plasmid-mediated quinolone resistance (PMQR) genes within the 55 oxyiminocephalosporin-resistant enterobacteria collected in a previous survey. The main PMQR determinants were aac(6')-Ib-cr and qnrB, which had prevalence rates of 42.4% and 3...

We synthesized a range of PQS (Pseudomonas quinolone signal; 2-heptyl-3-hydroxy-4(1H)-quinolone) analogues and tested them for their ability to stimulate MvfR-dependent pqsA transcription, MvfR-independent pyoverdine production, and membrane vesicle production. The structure-activity profile of the PQS analogues was different for each of these phenotypes. Certain inactive PQS analogues were als...

Analysis of 71 ciprofloxacin-resistant (MIC > or = 4 microg/ml) Streptococcus pneumoniae clinical isolates revealed only 1 for which the quinolone resistance-determining regions of the parC, parE, and gyrB genes were genetically related to those of viridans group streptococci. Our findings support the occurrence of interspecies recombination of type II topoisomerase genes; however, its contribu...

Four spontaneous, single-step mutants of Escherichia coli K-12 resistant to low levels of the cephalosporin 3'-quinolone ester Ro 23-9424 were isolated at a frequency of 10(-10) to 10(-11) mutants per CFU plated. The mutants were cross-resistant to both cephalosporin (cefotaxime) and quinolone (fleroxacin) components. Accordingly, they had altered porins and replicative DNA biosynthesis resista...

Two divergent synthetic routes are reported offering access to four quinolone natural products from Pseudonocardia sp. CL38489. Key steps to the natural products involved a regioselective epoxidation, an intramolecular Buchwald-Hartwig amination and a final acid-catalysed 1,3-allylic-alcohol rearrangement to give two of the natural products in one step. This study completes the synthesis of all...

Irloxacin and E-3846 are two new fluorinated quinolones. We evaluated the activities of these antimicrobial agents, ciprofloxacin, ofloxacin, enoxacin, pefloxacin, norfloxacin, and nalidixic acid against 1,161 bacterial strains. Ciprofloxacin was the most active quinolone. Irloxacin did not show great activity. The activity of E-3846 against gram-negative bacteria was similar to those of ofloxa...