title: Differences in the resistant variants of Enterobacter cloacae selected by extended-spectrum cephalosporins.
abstract: The rates of development of resistance to ceftriaxone, ceftazidime, cefepime, and cefpirome in 10 strains of Enterobacter cloacae were determined by daily transfer for 7 days to fresh medium containing twofold serial dilutions of the antibiotics. Development of resistance to ceftriaxone was the most rapid; this was followed by ceftazidime, cefpirome, and cefepime. Resistant variants selected by ceftriaxone and ceftazidime were cross-resistant and produced very high levels of beta-lactamase. On the other hand, resistant variants selected by cefepime and cefpirome often had moderately high levels of beta-lactamase and diminished levels of the 39- to 40-kDa porin protein.
authors.affiliation: Department of Microbiology, Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, Connecticut 06492, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Fung-Tomc
authors.forename: E
authors.initials: E
authors.lastname: Gradelski
authors.forename: E
authors.initials: E
authors.lastname: Huczko
authors.forename: T J
authors.initials: TJ
authors.lastname: Dougherty
authors.forename: R E
authors.initials: RE
authors.lastname: Kessler
authors.forename: D P
authors.initials: DP
authors.lastname: Bonner
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D000077723:Cefepime; D002442:Ceftazidime / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000032:analysis
chemical_list: D001425:Bacterial Outer Membrane Proteins; D002511:Cephalosporins; D002443:Ceftriaxone; D000077723:Cefepime; D002442:Ceftazidime; D001618:beta-Lactamases