Binding of the quinolone drug norfloxacin to gyrase and DNA has been investigated. We have detected binding to gyrase-DNA complex but find no significant binding to either gyrase or DNA alone. Enzyme containing gyrase A protein with the mutation Ser-83 to Trp (conferring quinolone resistance) showed greatly reduced drug binding.

Pseudomonas aeruginosa produces the quorum signal 2-heptyl-3-hydroxy-4-quinolone (Pseudomonas quinolone signal), which is important for stimulating outer membrane vesicle (MV) formation. Here we describe the importance of the 3-hydroxyl and 2-alkyl chain for MV production and the length of the 2-alkyl chain for association with MVs.

Two real-time polymerase chain reaction assays were developed to detect mutations in codons 83 and 87 in gyrA and in codons 80 and 91 in parC, the main sites that causes quinolone resistance in pathogenic Escherichia coli and Shigella spp. isolates. These assays can be employed as a useful method for controlling infections caused by quinolone-resistant E coli and Shigella isolates.

Quinolone-resistant Streptococcus agalactiae bacteria were recovered from single-patient isolates and found to contain mutations in the gyrase and topoisomerase IV genes. Pulsed-field gel electrophoresis demonstrated that four isolates from the same long-term care facility were closely related; in seven cases, quinolone-resistant Haemophilus influenzae and S. agalactiae bacteria were isolated f...

In three Escherichia coli mutants, a change (Ala-51 to Val) in the gyrase A protein outside the standard quinolone resistance-determining region (QRDR) lowered the level of quinolone susceptibility more than changes at amino acids 67, 82, 84, and 106 did. Revision of the QRDR to include amino acid 51 is indicated.

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...

OBJECTIVES The resistance of Streptococcus pneumoniae to the recently available antibiotic treatment has been a growing problem. The aim of the study was to determine the quinolone-resistant strains and detect the presence of mutations in the quinolone resistance-determining regions of the gyrA, parE, and parC genes. METHODS In this study, for the first time in Iran, the polymerase chain reac...

DNA gyrase is a target of quinolone antibacterial agents, but the molecular details of the quinolone-gyrase interaction are not clear. Quinolone resistance mutations frequently occur at residues Ser and Asp of the gyrase A subunit, suggesting that these residues are involved in drug binding. Single and double alanine substitutions were created at these positions (Ala, Ala, and Ala Ala), and the...

Although quinolone resistance usually results from chromosomal mutations, recent studies indicate that quinolone resistance can also be plasmid mediated. The gene responsible, qnr, is distinct from the known quinolone resistance genes and in previous studies seemed to be restricted to Klebsiella pneumoniae and Escherichia coli isolates from the University of Alabama in Birmingham, where this re...

Inhibition of DNA replication in an Escherichia coli dnaB-22 mutant failed to block quinolone-mediated lethality. Inhibition of protein synthesis by chloramphenicol inhibited nalidixic acid lethality and, to a lesser extent, ciprofloxacin lethality in both dnaB-22 and wild-type cells. Thus, major features of quinolone-mediated lethality do not depend on ongoing replication.