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Comparative Study
. 1990 Sep;34(9):1757-61.
doi: 10.1128/aac.34.9.1757.

New Norfloxacin Resistance Gene in Pseudomonas Aeruginosa PAO

Free PMC article
Comparative Study

New Norfloxacin Resistance Gene in Pseudomonas Aeruginosa PAO

H Fukuda et al. Antimicrob Agents Chemother. .
Free PMC article


A new type of norfloxacin-resistant mutant of Pseudomonas aeruginosa PAO was isolated. This mutant showed cross resistance to imipenem and chloramphenicol and hypersusceptibility to beta-lactam and aminoglycoside antibiotics. The new norfloxacin resistance gene nfxC was mapped near catA (46 min) on the PAO chromosome. Norfloxacin accumulation was decreased in the nfxC mutant; furthermore, the rate of imipenem diffusion through the outer membrane of the nfxC mutant was lower than that of the parent strain. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane proteins showed a decrease of a 46-kilodalton protein and an increase of a 50-kilodalton protein in the nfxC mutant. We conclude the nfxC is a new norfloxacin resistance gene that affects outer membrane permeability to quinolones and other antimicrobial agents.

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