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 q...

The Quail Neuroretina clone 71 gene (QNR-71) is expressed during the differentiation of retinal pigmented epithelia and the epidermis. It encodes a type I transmembrane glycoprotein that shares significant sequence homologies with several melanosomal proteins. We have studied its intracellular traffic in both pigmented and non-pigmented cells. We report that a di-leucine-based sorting signal (E...

Fluoroquinolones are an important class of wide-spectrum antibacterial agents. The first quinolone described was nalidixic acid, which showed a narrow spectrum of activity. The evolution of quinolones to more potent molecules was based on changes at positions 1, 6, 7 and 8 of the chemical structure of nalidixic acid. Quinolones inhibit DNA gyrase and topoisomerase IV activities, two enzymes ess...

BACKGROUND Salmonella and Shigella cause significant morbidity and mortality among children worldwide. Increased antimicrobial resistance results in greater burden of disease. MATERIALS AND METHODS From 2005 to 2011, Salmonella and Shigella isolates collected from ill children at a major hospital in Yucatan, Mexico, were subjected to serotyping and antimicrobial susceptibility testing by disk...

The qnr genes are plasmid-borne fluoroquinolone-resistance determinants widespread in Enterobacteriaceae. Three families of qnr determinants (qnrA, B and S) have been described, but little is known about their expression and regulation. Two new determinants, qnrC and qnrD, have been found recently. Here, we describe the characterization of the qnrB2 promoter and the identification of a LexA-bin...

The Qnr proteins belong to the pentapeptide repeat protein family. Despite each pentapeptide repeat unit being an important structural determinant, accurately determining pentapeptide repeat units in the Qnr proteins through sequence-based alignments has been challenging. In the present study, the pentapeptide repeat units of the nine representative Qnr proteins have been precisely determined v...

We found two NADH-dependent reductases (QNR and bacC) in Microbacterium luteolum JCM 9174 (M. luteolum JCM 9174) that can reduce 3-quinuclidinone to optically pure (R)-(-)-3-quinuclidinol. Alcohol dehydrogenase from Leifsonia sp. (LSADH) was combined with these reductases to regenerate NAD+ to NADH in situ in the presence of 2-propanol as a hydrogen donor. The reductase and LSADH genes were eff...