We isolated and characterized mutants of Bartonella bacilliformis that are resistant to the fluoroquinolone antibiotic ciprofloxacin, which targets the A subunit of DNA gyrase. Mutants had single point mutations in the gyrA gene that changed either Asp-90 to Gly or Asp-95 to Asn and had 3- or 16-fold higher resistance, respectively, to ciprofloxacin than did wild-type B. bacilliformis. Asp-95 i...

Background: Emergence Klebsiella pneumoniae resistant to quinolone antibiotics due to mutations in gyrA and parC genes created problem for treatment of patients in different hospitals in Iran. The objective of this study was to determine the amino acid substitutions of GyrA and ParC proteins in certain clonal lineages of the K. pneumoniae conferring high level quinolone resistance. Methods: One...

For 10 strains of Neisseria gonorrhoeae exhibiting decreased susceptibility to new quinolones (MIC, > or = 0.1 microgram/ml) isolated and preserved from patients with gonococcal urethritis during the period from February 1991 through January 1992. We investigated the mechanisms for development of resistance to new quinolones. After selecting 3 PCG-sensitive and new quinolone-resistant strains f...

An oligonucleotide biochip that specifically detects point mutations in the gyrA and parC genes of Neisseria gonorrhoeae was designed and subsequently evaluated with 87 untreated clinical specimens. The susceptibilities of the N. gonorrhoeae strains were tested to determine the prevalence of ciprofloxacin-resistant strains in Anhui Province, People's Republic of China. Conventional DNA sequenci...

We developed a novel rapid assay to detect the gyrA mutations that cause quinolone resistance in typhoid and paratyphoid fever Salmonella spp. using high-resolution melting (Idaho Technology, Salt Lake City, UT) analysis of polymerase chain reaction amplicons. The presence of gyrA mutations led to small but consistent changes in amplicon melting temperatures that allowed quinolone-resistant iso...

HIGHLIGHTS Mutational analysis of antibiotic resistant genes E. coli in UTI Patients. These were detected by PCR and sequenced using NGS. isolates positive for GyrA gene, GyrB tetB tetR gene. The novel mutation was gyrB gene at codon554.

Fluoroquinolone-resistant avian Escherichia coli isolates from northern Georgia were investigated for gyrA and parC mutations. All isolates contained a mutation in GyrA replacing Ser83 with Leu; seven isolates also contained mutations replacing Asp87 with either Gly or Tyr. Random amplified polymorphic DNA analysis revealed that quinolone-resistant E. coli isolates were genetically diverse.

The parC and gyrA genes of 73 ciprofloxacin-resistant and 6 ciprofloxacin-susceptible Enterococcus faecium clinical isolates were partly sequenced. Alterations in ParC and GyrA, possibly in combination with other resistance mechanisms, severely restricted the in vitro activities of the nine quinolones tested. For all isolates, clinafloxacin and sitafloxacin showed the best activities.

OBJECTIVES The use of rapid molecular assays for the detection of resistance to second-line drugs would significantly decrease the time delay in diagnosing drug-resistant tuberculosis (TB) that is associated with conventional phenotypic drug susceptibility testing. In this study, multiplex allele-specific (MAS)-PCR assays designed to detect the GyrA D94G and rrs A1401G mutations were evaluated ...

Among fluoroquinolone-resistant Mycobacterium tuberculosis (FQr-MTB) isolates, mutation at positions 90, 91, and 94 in gyrA gene and at positions 495, 516, and 533 in gyrB gene have been frequently reported. In this study, 35 isolates of FQr-MTB were collected from Siriraj Hospital and Chest Disease Institute. The quinolone-resistance-determining regions (QRDR) of gyrA and gyrB genes in all 35 ...