title: Imipenem resistance in Enterobacter aerogenes is associated with derepression of chromosomal cephalosporinases and impaired permeability.
abstract: Enterobacter aerogenes mutants with high-level resistance to imipenem were studied. They were derived from strains characterized by stable over-production of a class-I beta-lactamase. This enzyme (pI = 8.2) exhibited high affinity toward imipenem and hydrolysed the drug slowly. Imipenem-resistant mutants lacked a major 43-kDa outer membrane protein and displayed decreased permeability to cephaloridine. Introduction of a plasmid coding for the regulatory ampD gene abolished beta-lactamase production and rendered the mutants susceptible to imipenem.
authors.affiliation: Department of Bacteriology, Hellenic Pasteur Institute, Athens University, Greece.
authors.forename: L S
authors.initials: LS
authors.lastname: Tzouvelekis
authors.forename: E
authors.initials: E
authors.lastname: Tzelepi
authors.forename: A F
authors.initials: AF
authors.lastname: Mentis
authors.forename: A C
authors.initials: AC
authors.lastname: Vatopoulos
authors.forename: A
authors.initials: A
authors.lastname: Tsakris
mesh_terms: D002463:Cell Membrane Permeability; D002509:Cephaloridine / Q000378:metabolism; D002510:Cephalosporinase / Q000235:genetics / Q000378:metabolism*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004754:Enterobacter / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D015378:Imipenem / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics
chemical_list: D015378:Imipenem; D002510:Cephalosporinase; D002509:Cephaloridine