title: Interplay of impermeability and chromosomal beta-lactamase activity in imipenem-resistant Pseudomonas aeruginosa.
abstract: Mutational loss of the D2 porin causes imipenem resistance in Pseudomonas aeruginosa. It was found that this mechanism could function only when the chromosomal beta-lactamase was expressed. Mutants lacking both the beta-lactamase and the D2 porin were almost as susceptible as those that lacked the beta-lactamase but retained the porin. Thus, imipenem resistance reflected an interplay of the enzyme and impermeability, not either factor alone. These findings suggest that the activity of a carbapenem more beta-lactamase stable than imipenem should be less affected by the porin loss. Meropenem approached this behavior.
authors.affiliation: Department of Medical Microbiology, London Hospital Medical College, United Kingdom.
authors.forename: D M
authors.initials: DM
authors.lastname: Livermore
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D002876:Chromosomes, Bacterial / Q000201:enzymology*; D004352:Drug Resistance, Microbial; D015378:Imipenem / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010539:Permeability; D010641:Phenotype; D018272:Porins; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D018272:Porins; D015378:Imipenem; D001618:beta-Lactamases