title: Contribution of extended-spectrum AmpC (ESAC) beta-lactamases to carbapenem resistance in Escherichia coli.
abstract: ESAC beta-lactamases have increased catalytic efficiencies toward extended-spectrum cephalosporins and to a lesser extent toward imipenem as compared with the wild-type cephalosporinases. We show here that ESAC expression associated with the loss of both OmpC and OmpF porins conferred in Escherichia coli a high level of resistance to ertapenem and reduced the susceptibility to imipenem. On the contrary, ESAC expressed in the OmpC- or OmpF-deficient E. coli strains or narrow-spectrum cephalosporinase expressed in the OmpC-and OmpF-deficient strain do not confer reduced susceptibility to any of the carbapenems. The production of ESAC beta-lactamase in favorable E. coli background may represent an additional mechanism of resistance to ertapenem.
authors: Service de Bactériologie-Hygiène, Centre Hospitalier Universitaire d'Amiens, Hôpital Nord, Amiens, France. hedi.mammeri@bct.aphp.fr
authors: Hedi
authors: H
authors: Mammeri
authors: Patrice
authors: P
authors: Nordmann
authors: Amira
authors: A
authors: Berkani
authors: François
authors: F
authors: Eb
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism*; D015780:Carbapenems / Q000378:metabolism / Q000494:pharmacology*; D002511:Cephalosporins / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology; D015378:Imipenem / Q000378:metabolism; D018272:Porins / Q000235:genetics* / Q000302:isolation & purification; D001618:beta-Lactamases / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D002511:Cephalosporins; D018272:Porins; D015378:Imipenem; C048795:AmpC beta-lactamases; D001618:beta-Lactamases