The aim of this study was to examine mutations in the quinolone-resistance-determining region (QRDR) of gyrA and parC genes in Pseudomonas aeruginosa isolates. A total of 100 clinical P. aeruginosa isolates were collected from different university-affiliated hospitals in Tabriz, Iran. Minimum inhibitory concentrations (MICs) of ciprofloxacin and levofloxacin were evaluated by agar dilution assa...

The gene gyrA encoding the DNA gyrase A subunit of Klebsiella pneumoniae has been cloned in the plasmid pBR322. Bases of about 3.5 Kb DNA have been sequenced to locate the gyrA gene. An open reading frame of 2628 nucleotides coding for a 97 KD protein has been identified. Homology to the extent of about 85% was detected at the nucleotide level and about 90% at the amino acid level, when the seq...

AIM The present study was undertaken to characterize the mutation in gyrA (DNA gyrase) and parC (topoisomerase IV) genes responsible for fluoroquinolone resistance in Escherichia coli isolates associated with the bovine mastitis. MATERIALS AND METHODS A total of 92 milk samples from bovine mastitis cases were sampled in and around Puducherry (Southern India). Among these samples, 30 isolates ...

The presence of gyrA, gyrB and/or parC mutations, quinolone uptake, outer membrane protein profiles and epidemiological relationship were studied in 12 clinical isolates of Citrobacter freundii. No alterations were observed in the gyrB gene of any of the strains, or gyrA or parC of the four quinolone-susceptible strains (nalidixic acid MIC of 2-4 mg/L, and a ciprofloxacin MIC of 0.006-0.06 mg/L...

Helicobacter pylori strains with reduced susceptibility to fluoroquinolones have a mutation at either codon 87 Asn or 91 Asp of the gyrA gene. A rapid test based on an allele-specific PCR (AS-PCR) was designed to detect the gyrA mutations. Clinical H. pylori isolates were obtained from the stomachs of 51 patients with H. pylori infections who showed treatment failure. The MICs of gatifloxacin (...

The cloning and characterization of DNA gyrase genes from Mycobacterium smegmatis is described. The DNA sequence of 5119 bp encoding both gyrB and gyrA genes was determined. The gene gyrB precedes gyrA with a short intergenic region of 29 nucleotides. The proteins encoded, GyrB and GyrA, exhibit 45-80% identity to gyrase polypeptides from other bacteria. The genes were further engineered for ov...

We examined the antimicrobial susceptibilities of 85 Neisseria gonorrhoeae isolates, classified according to the presence of amino acid substitutions in the GyrA and ParC proteins, to 12 fluoroquinolones and 7 other antibiotics. Sitafloxacin and HSR-903 showed excellent activity against N. gonorrhoeae, including strains with both GyrA and ParC substitutions. Among the strains with various GyrA ...

Increasing numbers of fluoroquinolone-resistant Campylobacter coli isolates received at the Minnesota State Public Health Laboratory and at the Centers for Disease Control and Prevention have been a cause for concern. The gyrA quinolone resistance-determining regions of several fluoroquinolone-resistant isolates were sequenced to examine the mechanism of resistance. Ciprofloxacin-resistant C. c...

Escherichia coli DNA gyrase contains a 1:1 ratio of protomers coded by the genes gyrA and gyrB. This along with previous results shows that the enzyme has two copies of each protomer and thus a molecular weight of 400,000. Abortion of the gyrase reaction results in double-strand breakage of the DNA and covalent attachment of both gyrA protomers to the 5'-cut ends. We conclude that the gyrA prot...