A clinical isolate of Pseudomonas aeruginosa G48, became resistant during fluoroquinolone treatment giving rise to the post-therapy isolate, G49. To determine whether mutation in gyrA gave rise to fluoroquinolone resistance, G49 was transformed with a plasmid encoding gyrA (pNJR3-2); this reduced the MIC of fluoroquinolones for G49 two-fold. DNA sequencing of gyrA of G49 demonstrated a mutation...

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 ...

Malaria remains as one of the most deadly diseases in developing countries. The Plasmodium causative agents of human malaria such as Plasmodium falciparum possess an organelle, the apicoplast, which is the result of secondary endosymbiosis and retains its own circular DNA. A type II topoisomerase, DNA gyrase, is present in the apicoplast. In prokaryotes this enzyme is a proven, effective target...

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...

Mutations in quinolone targets were analysed in 80 unrelated nalidixic acid-resistant (NALR) Escherichia coli strains whose nalidixic acid and ciprofloxacin MICs ranged from 32 to >256 mg/L and 0.03-64 mg/L, respectively. These strains were isolated from food products (23) and faecal samples from humans (15) and healthy animals (42). Thirteen nalidixic acid-susceptible (NALS) E. coli strains we...

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...

BACKGROUND This study aimed to analyze the association of mutation patterns in gyrA and gyrB genes and the ofloxacin resistance levels in clinical Mycobacterium tuberculosis isolates sampled in 2009 from East China. METHODS The quinolone resistance-determining region of gyrA/B were sequenced in 192 M. tuberculosis clinical isolates and the minimal inhibitory concentrations (MICs) of 95 ofloxa...