The proportion of DNA gyrase mutants among quinolone-resistant strains of Pseudomonas aeruginosa was examined by introducing the cloned wild-type Escherichia coli gyrA and gyrB genes. Of 101 spontaneous mutants of P. aeruginosa PAO505, 33 (33%) were found to have gyrA mutations. Among 17 clinical isolates, 12 (71%) had gyrA mutations and 1 (6%) had a gyrB mutation.

The mutations that are responsible for fluoroquinolone resistance in the gyrA, gyrB, parC, and parE genes of Salmonella enterica serovar Typhi and serovar Paratyphi A were investigated. The sequences of the quinolone resistance-determining region of the gyrA gene in clinical isolates which showed decreased susceptibilities to fluoroquinolones had a single mutation at either the Ser-83 or the As...

The diversity of bacterial communities at three sites impacted by acid mine drainage (AMD) from the Yinshan Mine in China was studied using comparative sequence analysis of two molecular markers, the 16S rRNA and gyrB genes. The phylogenetic analyses retrieved sequences from six classes of bacteria, Nitrospira, Alphaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Acidobacteria, and Ac...

Fourteen quinolone-resistant Pseudomonas putida isolates were recovered from imported frozen shrimp sold in the United States. Two isolates harbored plasmids with qnrA and qnrB genes. PCR and DNA sequencing of quinolone resistance-determining regions identified novel substitutions in GyrA (His139→Glu and Thr128→Ala) and GyrB (Thr442→Asn, Gly470→Ala, and Ile487→Pro) and previously reported subst...

This study evaluated cross-resistance of Mycobacterium tuberculosis strains to ofloxacin, moxifloxacin, and gatifloxacin and investigated the presence of mutations in gyrA and gyrB. Fluoroquinolone susceptibilities were determined for 41 M. tuberculosis strains by the proportion method on 7H11, and MICs were determined by the resazurin microtiter assay. Forty strains shared the same resistance ...

The phylogenetic structure of genus Micromonospora within actinomycetes was examined by analysing the gyrB sequences of 15 validly described species and four subspecies. All but one of the Micromonospora strains formed a tight cluster, as had previously been demonstrated by a 16S rDNA-based phylogenetic analysis. However, the intrageneric relationships deduced from the gyrB-based phylogeny were...

Novobiocin-Sepharose was prepared by coupling of novobiocin to Epoxy-activated Sepharose 6B and used as an affinity adsorbent. Four novobiocin-binding proteins were isolated from crude extracts of Escherichia coli with molecular weights of 105, 92, 85 and 40 kdal. The two larger proteins were identified as the A subunit (gyrA protein) and the B subunit (gyrB protein) of DNA gyrase topoisomerase...

Bacteroides spp. has gained substantial interest among the suggested potential candidates for alternative faecal indicators for untreated recreational waters by the US EPA. Interest in Bacteroides as a faecal indicator is based upon the relative abundance of selected members of the Bacteroides genus in the human colon and human faeces. In this study, we developed a real-time PCR detection syste...