title: Extended-spectrum cephalosporinase in Acinetobacter baumannii.
abstract: An AmpC-type beta-lactamase conferring high-level resistance to expanded-spectrum cephalosporins and monobactams was characterized from an Acinetobacter baumannii clinical isolate. This class C beta-lactamase (named ADC-33) possessed a Pro210Arg substitution together with a duplication of an Ala residue at position 215 (inside the Omega-loop) compared to a reference AmpC cephalosporinase from A. baumannii. ADC-33 hydrolyzed ceftazidime, cefepime, and aztreonam at high levels, which allows the classification of this enzyme as an extended-spectrum AmpC (ESAC). Site-directed mutagenesis confirmed the role of both substitutions in its ESAC property.
authors.affiliation: Service de Bactériologie-Virologie, INSERM U914 Emerging Resistance to Antibiotics, Assistance Publique/Hôpital de Paris, Faculté deMédecine and Université Paris-Sud, France.
authors.forename: José-Manuel
authors.initials: JM
authors.lastname: Rodríguez-Martínez
authors.forename: Patrice
authors.initials: P
authors.lastname: Nordmann
authors.forename: Esthel
authors.initials: E
authors.lastname: Ronco
authors.forename: Laurent
authors.initials: L
authors.lastname: Poirel
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001398:Aztreonam / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D000077723:Cefepime; D002442:Ceftazidime / Q000494:pharmacology; D018550:Cephalosporin Resistance; D002510:Cephalosporinase / Q000235:genetics / Q000378:metabolism*; D002511:Cephalosporins / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D008997:Monobactams / Q000494:pharmacology*; D016297:Mutagenesis, Site-Directed; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D008997:Monobactams; D000077723:Cefepime; D002442:Ceftazidime; D002510:Cephalosporinase; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; D001398:Aztreonam