Fluoroquinolone resistance in Mycobacterium tuberculosis can be conferred by mutations in gyrA or gyrB. The prevalence of resistance mutations outside the quinolone resistance-determining region (QRDR) of gyrA or gyrB is unclear, since such regions are rarely sequenced. M. tuberculosis isolates from 1,111 patients with newly diagnosed culture-confirmed tuberculosis diagnosed in Tennessee from 2...

We investigated the contribution of quinolone resistance-determining region (QRDR) mutations to fluoroquinolone (enrofloxacin, orbifloxacin and danofloxacin) susceptibility in 58 Mycoplasma bovis isolates from dairy cattle in Japan. Fluoroquinolone non-resistant isolates (fluoroquinolone-MICs≤2 μg/ml) possessed no QRDR mutations (19 isolates) or Ser83Leu in GyrA (32 isolates). Fluoroquinolone-r...

During the early 1990s, a clone of multiresistant Salmonella enterica serovar Typhimurium O5 negative (var. Copenhagen) of phage type DT204c predominated in Germany and neighboring countries within the calf-fattening industry. In addition to being resistant to ampicillin, kanamycin, tetracycline, chloramphenicol, and trimethoprim, these isolates were highly resistant to nalidixic acid (MIC 128 ...

During the early 1990s, a clone of multiresistant Salmonella enterica serovar Typhimurium O5 negative (var. Copenhagen) of phage type DT204c predominated in Germany and neighboring countries within the calf-fattening industry. In addition to being resistant to ampicillin, kanamycin, tetracycline, chloramphenicol, and trimethoprim, these isolates were highly resistant to nalidixic acid (MIC 128 ...

Ninety-three Malaysian extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolates were investigated for ciprofloxacin resistance. Two mismatch amplification mutation (MAMA) assays were developed and used to facilitate rapid detection of gyrA and parC mutations. The isolates were also screened for plasmid-mediated quinolone resistance (PMQR) genes including aac(6')-Ib-cr, qepA...

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...

While Streptococcus pyogenes is consistently susceptible toward penicillin, therapeutic failure of penicillin treatment has been reported repeatedly and a considerable number of patients exhibit allergic reactions to this substance. At the same time, streptococcal resistance to alternative antibiotics, e.g., macrolides, has increased. Taken together, these facts demand the development of novel ...

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 ...

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...