We evaluated the in vitro activity of delafloxacin against a panel of 117 Neisseria gonorrhoeae strains, including 110 clinical isolates collected from 2012 to 2015 and seven reference strains, compared with the activities of seven antimicrobials currently or previously recommended for treatment of gonorrhea. We examined the potential for delafloxacin to select for resistant mutants in ciproflo...

Frequencies of mutation to resistance with trovafloxacin and four other quinolones were determined with quinolone-susceptible Staphylococcus aureus RN4220 by a direct plating method. First-step mutants were selected less frequently with trovafloxacin (1.1 x 10(-10) at 2 to 4x the MIC) than with levofloxacin or ciprofloxacin (3.0 x 10(-7) to 3.0 x 10(-8) at 2 to 4x the MIC). Mutants with a chang...

Mutations in the grlA and gyrA genes of 344 clinical strains of Staphylococcus aureus isolated in 1994 in Japan were identified by combinations of single-strand conformation polymorphism analysis, restriction fragment length analysis, and direct sequencing to identify possible relationships to fluoroquinolone resistance. Five types of single-point mutations and four types of double mutations we...

Quinolone susceptibility was analyzed in 17 clinical isolates of Corynebacterium striatum and 9 strains of Corynebacterium amycolatum by the E-test method in Mueller-Hinton agar plates. The C. striatum ATCC 6940 strain was used as a control strain. The amplified quinolone resistance determining regions of the gyrA genes of C. amycolatum and C. striatum were characterized. Four in vitro quinolon...

UNLABELLED Bacterial DNA is maintained in a supercoiled state controlled by the action of topoisomerases. Alterations in supercoiling affect fundamental cellular processes, including transcription. Here, we show that substitution at position 87 of GyrA of Salmonella influences sensitivity to antibiotics, including nonquinolone drugs, alters global supercoiling, and results in an altered transcr...

Antibacterial activities of gatifloxacin (AM1155), a new C-8-methoxy fluoroquinolone, and two structurally related compounds, AM1121 and ciprofloxacin, were studied with an isogenic set of ten quinolone-resistant, gyrA (gyrase) mutants of Escherichia coli. To compare the effect of each mutation on resistance, the mutant responses were normalized to those of wild-type cells. Alleles exhibiting t...

OBJECTIVE To determine the effect of growth of five strains of Salmonella enterica and their isogenic multiply antibiotic-resistant (MAR) derivatives with a phenolic farm disinfectant or triclosan (biocides) upon the frequency of mutation to resistance to antibiotics or cyclohexane. METHODS Strains were grown in broth with or without the biocides and then spread on to agar containing ampicill...

We examined antimicrobial susceptibility and efflux systems in laboratory-derived mutants of Salmonella enterica serovar Choleraesuis selected by culture on fluoroquinolone-containing plates. The mutants exhibited decreased susceptibilities to quinolones and several other antimicrobials. Mutations in the gyrA gene were not always found in the mutants. Accumulation assays revealed that intracell...

objective(s): we investigated the contribution of gyra and parc mutational mechanism in decreased ciprofloxacin susceptibility of acinetobacter baumannii isolated from burn wound infections. materials and methods: ciprofloxacin susceptibility of 50 a. baumannii isolates was evaluated by disk diffusion and agar dilution methods. pcr and sequencing were performed for detection of mutation in gyra...

BMS-284756 (T-3811) is a novel quinolone that lacks a fluorine at the C-6 position. BMS-284756 has a broad spectrum of antibacterial activity (3, 7). The purpose of the present study was (i) to analyze the in vitro activity of the novel quinolone against mutants of Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus selected with marketed quinolones and (ii) to investiga...