Fluoroquinolone-resistant mutants of Mycoplasma hominis were selected in vitro from the PG21 susceptible reference strain either by multistep selection on increasing concentrations of various fluoroquinolones or by one-step selection on agar medium with ofloxacin. The quinolone resistance-determining regions (QRDR) of the structural genes encoding the A and b subunits of DNA gyrase were amplifi...

BACKGROUND A progressive frequency of resistance to fluoroquinolones is observed among Gram-negative bacilli. AIM To investigate the mechanism of resistance to fluoroquinolones mediated by mutations affecting gyrA and gyrB genes in strains of Gram negative bacüli isolated from CMean hospitals. MATERIAL AND METHOD Minimal inhibitory concentration of fluoroquinolones was determined in 91 rand...

DNA gyrase is the bacterial DNA topoisomerase (topo) that supercoils DNA by using the free energy of ATP hydrolysis. The enzyme, an A(2)B(2) tetramer encoded by the gyrA and gyrB genes, catalyses topological changes in DNA during replication and transcription, and is the only topo that is able to introduce negative supercoils. Gyrase is essential in bacteria and apparently absent from eukaryote...

To investigate the mechanism of resistance in the isolates, fragments of gyrA (847 bp) and parC (822 bp) genes were amplifi ed by using primers gyrA1F (5′-gttttcccagtcacgacgttgtaATGA CCGACGCAACCATCCGCCAC-3′) and gyrA-1R (5′-ttgtgagcggataacaattt cCCAGCTTGGCTTTGTTGACCTG ATAG-3′), and parC-1F (5′-gttttcccag tcacgacgttgtaATGAATACGCAAGC GCACGCCCCA-3′) and parC-1R (5′ttgtgagcggataacaatttcGGAATTGGC GT...

BACKGROUND The emergence of extensively drug-resistant tuberculosis (XDR-TB) has raised public health concern for global TB control. Although multi drug-resistant tuberculosis (MDR- TB) prevalence and associated genetic mutations in Morocco are well documented, scarce information on XDR TB is available. Hence, the evaluation of pre-XDR and XDR prevalence, as well as the mutation status of gyrA,...

Three isolates of Streptococcus agalactiae highly resistant to multiple fluoroquinolones were isolated in Japan. Compared with susceptible strains of S. agalactiae, these quinolone-resistant strains had double point mutations within the quinolone resistance-determining regions of gyrA and parC; Ser-81 was changed to Leu (TCA --> TTA) in the amino acid sequence deduced from gyrA, and Ser-79 was ...

Introduction: The major resistance mechanisms of Pseudomonas aeruginosa to fluoroquinolones and carbapenems are associated with the mutations in the genes gyrA and oprD encoding type II topoisomerases (DNA gyrase) and OprD porin, respectively. Method: In this cross-sectional study, sixty five clinical samples were collected from patients hospitalized in Al-Zahra Hospital of Isfahan, Iran. Susce...

Resistance to fluoroquinolone (FQ) antibiotics in Streptococcus pneumoniae has been attributed primarily to specific mutations in the genes for DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE). Resistance to some FQs can result from a single mutation in one or more of the genes encoding these essential enzymes. A group of 160 clinical isolates of pneumococci was examined in this ...