The objective of this study was to compare quinolone resistance and gyrA mutations in clinical isolates of Klebsiella pneumoniae and Escherichia coli from Chinese adults who used quinolone in the preceding month and children without any known history of quinolone administration. The antimicrobial susceptibilities of 61 isolates from children and 79 isolates from adults were determined. The muta...

Fluoroquinolones acting equally through DNA gyrase and topoisomerase IV in vivo are considered desirable in requiring two target mutations for emergence of resistant bacteria. To investigate this idea, we have studied the response of Staphylococcus aureus RN4220 to stepwise challenge with sparfloxacin, a known dual-target agent, and with NSFQ-105, a more potent sulfanilyl fluoroquinolone that b...

Title of Dissertation: CHARACTERIZATION AND MOLECULAR MECHANISMS OF ANTIMICROBIAL RESISTANCE IN FOODBORNE PATHOGENS Sheng Chen, Doctor of Philosophy, 2004 Dissertation directed by: Associate Professor Jianghong Meng Department of Nutrition and Food Science The emergence of antimicrobial resistance bacteria in both the medical and agricultural fields has become a serious problem worldwide. The u...

Genes encoding the quinolones resistance determining regions (QRDRs) in Streptococcus pneumoniae were detected by PCR and the sequence analysis was carried out to identify point mutations within these regions. The study was carried out to observe mutation patterns among S. pneumoniae strains in Malaysia. Antimicrobial susceptibility testing of 100 isolates was determined against various antibio...

The goal of our research was to detect mutations on gyrA gene in a small collection of Salmonella enterica serovar Enteritidis (S. Enteritidis) isolated from stool specimens, food and poultry in quinolone resistant strains. Out of 60 randomly selected isolates, resistance to nalidixic acid was exhibited by 15%. Five isolates were from poultry, three isolates were from stools and one was found i...

OBJECTIVES The aim of this study was to assess the prevalence rate of primary fluoroquinolone resistance in Helicobacter pylori isolates from Korean patients over the past 16 years. METHODS One hundred and thirty-five strains of H. pylori (34 strains in 1987, 36 in 1994 and 65 in 2003) were isolated from antral gastric mucosal biopsy specimens. The determination of MICs for the H. pylori isol...

Mechanisms of antibiotic resistance were examined in nalidixic acid-resistant Salmonella enterica serovar Enteritidis field isolates displaying decreased susceptibility to ciprofloxacin and in in vitro-derived ciprofloxacin-resistant mutants (104-cip and 5408-cip). All field isolates harbored a single gyrA mutation (D87Y). Deletion of acrB and complementation with wild-type gyrA increased quino...

We have analyzed by gene amplification and sequencing mutations in the quinolone resistance-determining regions of the gyrA, gyrB, and parC genes of fluoroquinolone-resistant Streptococcus pneumoniae mutants obtained during therapy or in vitro. Mutations leading to substitutions in ParC were detected in the two mutants obtained in vivo, BM4203-R (substitution of a histidine for an aspartate at ...

Despite the rapid spread of antibiotic resistance among gonococci worldwide, limited reports are available from Brazilian locations. In the present study, 25 quinolone-resistant Neisseria gonorrhoeae (QRNG) strains isolated in Rio de Janeiro, Brazil, were characterized by phenotypic and molecular methods, including analysis of mutations in the gyrA and parC genes. They represented 16.5% of the ...

Twenty-eight strains of Pseudomonas aeruginosa with various degrees of norfloxacin resistance were isolated from patients with urinary tract infections. P. aeruginosa strains (norfloxacin MICs, 3.13 to 200 micrograms/ml) were transformed by either pPAW207 or pNF111 plasmid DNA, which included either the gyrA or nfxB gene, respectively. For transformants with pPAW207, norfloxacin MICs decreased ...