objective(s): we investigated the contribution of gyra and parc mutational mechanism in decreased ciprofloxacin susceptibility of acinetobacter baumannii isolated from burn wound infections. materials and methods: ciprofloxacin susceptibility of 50 a. baumannii isolates was evaluated by disk diffusion and agar dilution methods. pcr and sequencing were performed for detection of mutation in gyra...

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...

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...

Objective(s): Regarding the global burden of uropathogenic Escherichia coli (UPEC) infections, prevention and treatment of such infections play a significant role in healthcare management. The inordinate use of fluoroquinolones led to a worldwide spread of quinolone-resistant strains. Therefore, this study aimed to investigate mutations in codons 83 and 106 of gyrA gene in UPEC isolates in the ...

In order to study the interactions between Escherichia coli DNA gyrase and the gyrase interacting protein QnrB in vivo, we constructed a gyrB-gyrA fusion and validated its ability to correct the temperature-sensitive growth of gyrA and gyrB mutants. Like wild-type gyrA, the gyrB-gyrA fusion complemented a quinolone-resistant gyrA mutant to increase susceptibility. It functioned as an active typ...

OBJECTIVES This study was aimed at characterizing the gyrA locus and determining its impact on fluoroquinolone susceptibility, DNA supercoiling degree and growth rate of Salmonella Typhimurium live vaccine strain vacT in comparison with its parent M415. Furthermore, the role of multiple drug resistance efflux in the susceptibility of vacT to fluoroquinolones and macrolides was investigated. M...

Fluoroquinolones form drug-topoisomerase-DNA complexes that rapidly block transcription and replication. Crystallographic and biochemical studies show that quinolone binding involves a water/metal-ion bridge between the quinolone C3-C4 keto-acid and amino acids in helix-4 of the target proteins, GyrA (gyrase) and ParC (topoisomerase IV). A recent cross-linking study revealed a second drug-bindi...