title: Modifications of DNA-gyrase and of permeability in a norfloxacin-resistant clinical isolate of Providencia stuartii.
abstract: We obtained a clinical isolate of Providencia stuartii showing a high level of resistance to norfloxacin and to other 4-quinolones, whose target is the enzyme DNA-gyrase. This strain showed resistance also to beta-lactam and aminoglycoside antibiotics. In order to detect modification of DNA-gyrase, we performed supercoiling assays in vitro in presence of norfloxacin and ciprofloxacin. Furthermore, outer membrane proteins, which are involved in permeability mechanisms, were analyzed on SDS-polyacrylamide gels. Results showed that both modifications in DNA-gyrase and changes in outer membrane proteins can be held responsible for resistance to 4-quinolones; moreover, these modification are probably supported by a third mechanism of resistance.
authors.affiliation: Istituto di Microbiologia, Università di Pavia, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Landini
authors.forename: L
authors.initials: L
authors.lastname: Pagani
authors.forename: L
authors.initials: L
authors.lastname: Debiaggi
authors.forename: P M
authors.initials: PM
authors.lastname: Cereda
authors.forename: E
authors.initials: E
authors.lastname: Romero
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D002462:Cell Membrane / Q000032:analysis / Q000187:drug effects; D002463:Cell Membrane Permeability; D002939:Ciprofloxacin / Q000494:pharmacology*; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000187:drug effects; D004352:Drug Resistance, Microbial; D004591:Electrophoresis, Polyacrylamide Gel; D009154:Mutation; D009643:Norfloxacin / Q000494:pharmacology*; D011511:Proteus / Q000201:enzymology*; D011532:Providencia / Q000032:analysis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D059005:Topoisomerase II Inhibitors
chemical_list: D001425:Bacterial Outer Membrane Proteins; D004278:DNA, Superhelical; D059005:Topoisomerase II Inhibitors; D002939:Ciprofloxacin; D004250:DNA Topoisomerases, Type II; D009643:Norfloxacin