Sir, Quinolone resistance in Enterobacteriaceae usually results from mutations in genes coding for chromosomally encoded type II topoisomerases, efflux pumps or porin-related proteins. Recently, transferable, plasmid-borne, quinolone resistance genes—qnrA, qnrB, qnrS, cr variant of aac(60)-Ib, qepA and oxqB—have been observed in clinical isolates, more frequently among strains producing plasmid...

During investigations on the regulation of the Pax-6 gene, we characterized a cDNA from quail neuroretina showing a 5' untranslated region distinct from that previously described and initiated from an internal promoter. Using RNase protection and primer extension mapping, we localized this second quail Pax-6 promoter, termed P1. As reported for the already described P0 promoter, P1 was also tra...

BACKGROUND Considering the importance of hospital wastewaters as potential reservoirs for the dissemination of bacterial pathogens such as Escherichia coli and antibiotic resistance genes in the environment, the need for such information becomes imperative. METHODS E. coli strains were isolated from hospital wastewater sources in Tehran, Iran, over a 24-month sampling period (Jun 2014- Jun 20...

qnr genes were discovered on plasmids by their ability to reduce quinolone susceptibility, but homologs can be found in the genomes of at least 92 Gram-negative, Gram-positive, and strictly anaerobic bacterial species. The related pentapeptide repeat protein-encoding mfpA gene is present in the genome of at least 19 species of Mycobacterium and 10 other Actinobacteria species. The native functi...

background and aims: extended-spectrum β-lactamase (esbl) producing gram negative bacteria are resistant to penicillins, narrow and extended-spectrum cephalosporins, and aztreonam; also they are frequently resistant to trimethoprim-sulfamethoxazole, aminoglycosides, and quinolones. this study aimed to investigate the prevalence of plasmid-mediated quinolone resistance (pmqr) determinants qnra, ...

This study assessed the functional importance of residues located at the i(-2) position of face 4 of the tandem repeat loops of the quinolone resistance protein QnrVC7 through mutagenesis studies. The i(-2) position of face 4 on different coils required residues with different natures. Some substitutions reduced the protective activity of QnrVC7, while some of them increased it. These findings ...