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...

Monitoring the antibiotic susceptibility pattern of Salmonella enterica serovar Typhi (S. Typhi) is important for efficiently managing cases of typhoid fever. In this study, the antimicrobial susceptibility patterns of 114 S. Typhi isolates, which were collected from a university hospital in Nepal during July 2009-December 2010, were investigated by disc diffusion assays. All of the S. Typh...

Modern phylogenetic studies may benefit from the analysis of complete genome sequences of various microorganisms. Evolutionary inferences based on genome-scale analysis are believed to be more accurate than the gene-based alternative. However, the computational complexity of current phylogenomic procedures, inappropriateness of standard phylogenetic tools to process genome-wide data, and lack o...

Escherichia coli isolates from diseased piglets (n = 89) and chickens (n = 71) in China were characterized for O serogroups, virulence genes, antimicrobial susceptibility, class 1 integrons, and mechanisms of fluoroquinolone resistance. O78 was the most common serogroup identified (63%) among the chicken E. coli isolates. Most isolates were PCR positive for the increased serum survival gene (is...

Antimicrobial-resistant bacteria pose a threat to public health. Three Yersinia enterocolitica strains cultured from patients presenting with diarrhea and resistant to nalidixic acid were studied. Target gene mutations in gyrA alone were identified as part of the genetic basis for this phenotype. Efflux activity was also noted, since the presence of the efflux pump inhibitor, phenylalanine-argi...

We have identified a topoisomerase activity from Escherichia coli related to DNA gyrase (topoisomerase II): we designate it topoisomerase II'. It was constructed of two subunits, which were purified separately. One is the product of the gyrA (formerly nalA) gene and is identical to subunit A of DNA gyrase. The other is a 50,000-dalton protein, which we have purified to homogeneity and call v. v...

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...