Type II topoisomerases, including DNA gyrase (GyrA) and topoisomerase IV (ParC), contribute to fluoroquinolone resistance in Enterococcus spp. This study investigated the mutational status of quinolone resistance-determining regions (QRDRs) GyrA ParC clinical isolates enterococci from a hospital Baotou, China. We analyzed 110 enterococcal isolates, 57 faecalis 53 faecium. The rates E. faecium c...

Three isolates of Streptococcus agalactiae highly resistant to multiple fluoroquinolones were isolated in Japan. Compared with susceptible strains of S. agalactiae, these quinolone-resistant strains had double point mutations within the quinolone resistance-determining regions of gyrA and parC; Ser-81 was changed to Leu (TCA --> TTA) in the amino acid sequence deduced from gyrA, and Ser-79 was ...

OBJECTIVES To investigate the mechanism of ciprofloxacin resistance in isolates of Acinetobacter baumannii during two hospital outbreaks and to determine the expression level of the gene encoding the AdeB efflux pump. METHODS Isolates were previously typed by PFGE and their MICs determined by broth microdilution. The gyrA and parC genes were sequenced and the adeB gene examined by real-time r...

BACKGROUND Wide use of ciprofloxacin and levofloxacin has often led to increased resistance. The resistance rate to these two agents varies in different clinical isolates of Enterobacteriaceae. Mutations of GyrA within the quinolone resistance-determining regions have been found to be the main mechanism for quinolone resistance in Enterobacteriaceae. It has been shown that only some of the muta...

The objective of this study was to identify mutations in the Quinolone Resistance Determining sources Regions (QRDR) of the gyrA, gyrB, parC, and parE genes and to determine if any of the qnr variants or the aac(6')-Ib-cr variant were present in strains of Salmonella spp. isolated in Brazil. A total of 126 Salmonella spp. strains from epidemic (n = 114) and poultry (n = 12) origin were evaluate...

The F plasmid-carried bacterial toxin, the CcdB protein, is known to act on DNA gyrase in two different ways. CcdB poisons the gyrase-DNA complex, blocking the passage of polymerases and leading to double-strand breakage of the DNA. Alternatively, in cells that overexpress CcdB, the A subunit of DNA gyrase (GyrA) has been found as an inactive complex with CcdB. We have reconstituted the inactiv...

Ciprofloxacin, a quinolone with good intracellular penetration may possibly be used for treatment of melioidosis caused by Burkholderia pseudomallei, but problems with resistance may be encountered. Amino acid substitutions in gyrA/gyrB have given rise to fluoroquinolone resistance in various microorganisms. Using published primers for gyrA and gyrB, PCR was performed on 11 isolates of B. pseud...

Introduction Pseudomonas aeruginosa has many mechanisms of resistance to fluoroquinolones. The main mechanism is to change the effect of two enzymes that open the DNA helix - the enzyme DNA gyrase (gyrA) and the topoisomerase IV (parC). In addition, mutations that render the MexAB-oprM pump (mexR) dysfunctional, leading to its overexpression, also enhance resistance to fluoroquinolones. In this...

Among 73 clinical isolates of Pseudomonas aeruginosa 48 strains were ciprofloxacine (CIP) susceptible and 25 CIP resistant (Minimal inhibitory concentration--MIC>32 microg/ml - 14 strains) or of intermediate susceptibility to CIP (MIC > or = 1,5 - 32 microg/ml - 11 isolates). Mutations in the quinolone-resistance-determining region (QRDR) of gyrA gene were searched in groups of CIP resistant an...