Contribution of extended-spectrum AmpC (ESAC) β-lactamases to carbapenem resistance in Escherichia coli

Authors

  • Hedi Mammeri,

    1. Service de Bactériologie-Hygiène, Centre Hospitalier Universitaire d'Amiens, Hôpital Nord, Amiens, France
    2. Service de Bactériologie-Virologie-Hygiène, Faculté de Médecine, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Université Paris Sud, Paris-Sud, K.-Bicêtre, France
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  • Patrice Nordmann,

    1. Service de Bactériologie-Virologie-Hygiène, Faculté de Médecine, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Université Paris Sud, Paris-Sud, K.-Bicêtre, France
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  • Amira Berkani,

    1. Service de Bactériologie-Hygiène, Centre Hospitalier Universitaire d'Amiens, Hôpital Nord, Amiens, France
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  • François Eb

    1. Service de Bactériologie-Hygiène, Centre Hospitalier Universitaire d'Amiens, Hôpital Nord, Amiens, France
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  • Editor: Anthony George

Correspondence: Hedi Mammeri, Service de Bactériologie-Hygiène, Centre Hospitalier Universitaire d'Amiens, Hôpital Nord, Place Victor Pauchet, 80000 Amiens Cedex, France. Tel.: +33 3 22 66 84 35; fax: 33 1 33 22 84 35; e-mail: hedi.mammeri@bct.aphp.fr

Abstract

ESAC β-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 β-lactamase in favorable E. coli background may represent an additional mechanism of resistance to ertapenem.

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