Real-time PCR assays were developed for the enumeration of plasmid-mediated quinolone resistance (PMQR) determinants, such as the qnrA, qnrB, and qnrS genes, in different water samples and chicken feces. The results indicate that the developed assays are specific and sensitive for the quantification of qnr genes in complex samples.

The increased use of fluoroquinolones has led to increasing resistance to these antimicrobials, with rates of resistance that vary by both organism and geographic region. Resistance to fluoroquinolones typically arises as a result of alterations in the target enzymes (DNA gyrase and topoisomerase IV) and of changes in drug entry and efflux. Mutations are selected first in the more susceptible t...

Fourteen strains of S. Typhi (n=13) and S. Paratyphi A (n=1) resistant to ciprofloxacin were compared with 30 ciprofloxacin decreased-susceptibility strains on the basis of qnr plasmid analysis, and nucleotide substitutions at gyrA, gyrB, parC and parE. In ciprofloxacin-resistant strains, five S. Typhi and a single S. Paratyphi A showed triple mutations in gyrA (Ser83-->Phe, Asp87-->Asn, Glu133...

increase in the number of different qnr-positive serotypes was observed in 2007, although the total number of positive isolates was evenly distributed between 2003 and 2007 (Table 1). The qnrS1 variant was highly prevalent in Salmonella Corvallis supporting the results recently published from Denmark, the Netherlands and the UK. 2,6,8 The Danish study included a restricted set of Salmonella Cor...

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...

OBJECTIVES The aim of this study was to determine the occurrence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli at an equine clinic and a horseback riding centre, and to discuss the impact of antimicrobial treatment on resistance selection. METHODS Faeces from horses, environmental smears and flies were sampled at both the clinic and riding centre. Staff at the equine clin...

OBJECTIVES A burn unit of a hospital in Tunis underwent an endemic situation caused by imipenem-resistant Pseudomonas aeruginosa. For nine non-repetitive isolates of a clonal VIM-2-producing strain, the blaVIM-2 genetic background was characterized and the associated qnrVC1 gene molecularly analysed. METHODS The imipenem resistance mechanism was investigated by phenotypic and molecular tests,...