We determined the prevalence of fluoroquinolone resistance among the isolates of Mycobacterium tuberculosis from 605 pulmonary tuberculosis patients in Shanghai, China. Mutations in gyrA were found in 81.5% of phenotypically fluoroquinolone-resistant isolates and were used as a molecular marker of fluoroquinolone resistance. gyrA mutations were detected in 1.9% of strains pan-susceptible to fir...

The accuracy of genotypic resistance to levofloxacin (gyrA mutations) and its agreement with treatment outcomes after levofloxacin-based therapy have not been reported. We aimed to assess the correlation. Helicobacter pylori strains isolated from patients who received levofloxacin-based and clarithromycin-based triple therapies in a previous randomized trial were analyzed for point mutations in...

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 ...

MICs of DU-6859a, a novel fluoroquinolone, for 18 Klebsiella pneumoniae isolates and 21 Enterobacter cloacae isolates with altered GyrA or altered GyrA and ParC ranged from < or =0.025 to 6.25 microg/ml and from 0.1 to 3.13 microg/ml, respectively. Based on the MICs at which 90% of the isolates were inhibited for these strains of K. pneumoniae and E. cloacae, DU-6859a exhibited 16- to 256-fold-...

gyrA mutations in quinolone-resistant pathogenic isolates of Staphylococcus spp. have been detected by the direct HinfI digestion of polymerase chain reaction products. Homology among gyrA genes allowed rapid examination of both coagulase-positive and -negative isolates. DNA sequence analysis revealed that ciprofloxacin resistance in Staphylococcus epidermidis is associated with a novel Ser-84-...

A fragment of the gyrA gene was sequenced from 34 isolates of Campylobacter coli, including 23 isolates resistant to ciprofloxacin. All ciprofloxacin-resistant isolates examined by DNA sequencing carried a point mutation at position Thr-86 on the gyrA gene product, involving the replacement of Thr-86 by Ile. A combined PCR-restriction fragment length polymorphism technique using RsaI was develo...

Several studies have been conducted in recent years to elucidate the structure, function and significance of AcrB, MarA, SoxS and RamA in Salmonella enterica. In this study, the relative quantification of acrB, soxS, marA and ramA genes expression was evaluated in 14 strains of S. enterica, with or without accompanying mutations in the quinolone resistance-determining regions of the gyrA gene, ...

In the study, the ciprofloxacin resistance rate was 100%. High-level ciprofloxacin resistance rate was 63.55%. Sixteen different mutation patterns involved in the formation of ciprofloxacin resistance were identified. The most prevalent were patterns P7 (25.2%), P8 (15.0%), P9 (11.2%), P1 (10.3%), and P5 (10.3%). All of the 107 NG isolates analyzed for mutations in the study have demonstrated a...

Campylobacter spp. are common pathogenic bacteria in both veterinary and human medicine. Infections caused by Campylobacter spp. are usually treated using antibiotics. However, the injudicious use of antibiotics has been proven to spearhead the emergence of antibiotic resistance. The purpose of this study was to detect the prevalence of antibiotic resistance genes in Campylobacter spp. isolated...