To compare mutations in the DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE) genes of Clostridium perfringens, which are associated with in vitro exposure to fluoroquinolones, resistant mutants were selected from eight strains by serial passage in the presence of increasing concentrations of norfloxacin, ciprofloxacin, gatifloxacin, or trovafloxacin. The nucleotide sequences of t...

OBJECTIVES To assess the ciprofloxacin resistance of Neisseria meningitidis isolated from 1999 through 2006 in Spain, susceptibility testing was conducted on 5300 isolates. METHODS Ten isolates showed MICs of ciprofloxacin ranging between 0.06 and 0.25 mg/L, and they were characterized by analysis for mutations within the quinolone resistance determining regions (QRDRs) in the gyrA, gyrB, par...

background: enterobacteriaceae are a large group of bacteria widely distributed in nature. escherichia coli is the most com­mon cause of urinary tract infection. two amino acid substitutions, in gyra, are commonly responsible for quinolone re­sistance in e. coli . the aim of this study was molecular survey of nalidixic acid resistance e.coli isolated from patients in the codones of 83 and 87 gy...

Turtle-borne Salmonella enterica owns significance as a leading cause in human salmonellosis. The current study aimed to determine the quinolone susceptibility and the genetic characteristics of 21 strains of S. enterica subsp. enterica isolated from pet turtles. Susceptibility of four antimicrobials including nalidixic acid, ciprofloxacin, ofloxacin, and levofloxacin was examined in disk diffu...

OBJECTIVES The aim of this study was to characterize fluoroquinolone-resistant Shigella and determine whether the qnr and aac(6')-Ib-cr genes could contribute to sporadic shigellosis at the clinic in the Hangzhou area of China. METHODS A total of 202 strains of Shigella (79 Shigella sonnei and 123 Shigella flexneri ) isolated from sporadic cases of shigellosis from 1998 to 2007 were analysed ...

OBJECTIVES To investigate quinolone resistance mechanisms in an Escherichia coli clinical isolate (Ar2) resistant to ofloxacin but susceptible to nalidixic acid selected after 10 days of ofloxacin therapy in a patient with prostatitis. METHODS Molecular typing (ERIC-PCR and RAPD), antibiotic susceptibility and gyrA, gyrB, parC and parE QRDR sequences were compared for E. coli Ar2 and a wild-t...

The in vitro activity of clinafloxacin was studied in comparison with ciprofloxacin, levofloxacin, moxifloxacin, nalidixic acid, sparfloxacin and trovafloxacin against Acinetobacter baumannii clinical isolates. Clinafloxacin showed a MIC(90) of 4 mg/L, whereas the remaining quinolones showed a MIC(90) equal to or higher than 16 mg/L. MIC(50) determination in the presence of reserpine resulted i...

OBJECTIVES Fluoroquinolone-resistant Streptococcus pneumoniae are increasing worldwide rapidly. In vitro activities of sitafloxacin were evaluated against clinical isolates of S. pneumoniae resistant to levofloxacin (MIC of levofloxacin > or = 4 mg/L), which were characterized genetically. METHODS The quinolone resistance determining regions (QRDRs) of gyrA, gyrB, parC and parE of these strai...

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...

Point mutations in the topoisomerase (DNA gyrase A) gene are known to be associated with fluoroquinolone resistance in Campylobacter. Recent studies have shown that an efflux pump encoded by cmeABC is also involved in decreased susceptibilities to fluoroquinolones, as well as other antimicrobials. Genome analysis suggests that Campylobacter jejuni contains at least nine other putative efflux pu...