title: Occurrence of efflux mechanism and cephalosporinase variant in a population of Enterobacter aerogenes and Klebsiella pneumoniae isolates producing extended-spectrum beta-lactamases.
abstract: We investigated the occurrence of multidrug resistance in 44 Enterobacter aerogenes and Klebsiella pneumoniae clinical isolates. Efflux was involved in resistance in E. aerogenes isolates more frequently than in K. pneumoniae isolates (100 versus 38% of isolates) and was associated with the expression of phenylalanine arginine beta-naphthylamide-susceptible active efflux. AcrA-TolC overproduction in E. aerogenes isolates was noted. An analysis of four E. aerogenes isolates for which cefepime MICs were high revealed no modification in porin expression but a new specific mutation in the AmpC beta-lactamase.
authors.affiliation: Facultés de Médecine et Pharmacie, Transporteurs Membranaires, Chimioresistance et Drug-Design, UMR-MD1, Université de la Méditerranée, Marseille, France.
authors.forename: Que-Tien
authors.initials: QT
authors.lastname: Tran
authors.forename: Myrielle
authors.initials: M
authors.lastname: Dupont
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Lavigne
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Chevalier
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Pagès
authors.forename: Albert
authors.initials: A
authors.lastname: Sotto
authors.forename: Anne
authors.initials: A
authors.lastname: Davin-Regli
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D000077723:Cefepime; D002510:Cephalosporinase / Q000502:physiology*; D002511:Cephalosporins / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D021902:Enterobacter aerogenes / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D002511:Cephalosporins; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000077723:Cefepime; D002510:Cephalosporinase; C048795:AmpC beta-lactamases; D001618:beta-Lactamases