title: [Phenotypic and genotypic characterization of resistance to third-generation cephalosporins in Enterobacter spp].
abstract: Enterobacter spp. are becoming increasingly frequent nosocomial pathogens with multiple resistance mechanism to beta-lactam antibiotics. We carried out the phenotypic and genotypic characterization of beta-lactamases in 27 Enterobacter spp. (25 Enterobacter cloacae y 2 Enterobacter aerogenes), as well as the ability of different extended spectrum-lactamase (ESBL) screening methods. Resistance to third generation cephalosporins was observed in 15/27 (63%) isolates. Twelve resistant isolates produced high level chromosomal encoded AmpC beta-lactamase; 6 of them were also producers of PER-2. Resistance to third generation cephalosporins in the remaining 3 isolates was due to the presence of ESBLs, PER-2 in 2 cases, and CTX-M-2 in the other. Only CTX-M-2 production was detected with all tested cephalosporins using difusion synergy tests, while cefepime improved ESBLs detection in 7/8 PER-2 producers, 4/8 in the inhibitor approximation test and 7/8 with double disk test using cefepime containing disk with and without clavulanic acid. Dilution method, including cephalosporins with and without the inhibitor detected 1/9 ESBLs producers.
authors.affiliation: Carrera de Especialización en Bioquímica Clínica, área Bacteriología Clínica, Escuela de graduados, Junín 956 CP 1113.
authors.forename: E
authors.initials: E
authors.lastname: Bertona
authors.forename: M
authors.initials: M
authors.lastname: Radice
authors.forename: C H
authors.initials: CH
authors.lastname: Rodríguez
authors.forename: C
authors.initials: C
authors.lastname: Barberis
authors.forename: C
authors.initials: C
authors.lastname: Vay
authors.forename: A
authors.initials: A
authors.lastname: Famiglietti
authors.forename: G
authors.initials: G
authors.lastname: Gutkind
mesh_terms: D018550:Cephalosporin Resistance / Q000235:genetics; D002511:Cephalosporins / Q000145:classification / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D021902:Enterobacter aerogenes / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D005838:Genotype; D006801:Humans; D007526:Isoelectric Point; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D002511:Cephalosporins; D001618:beta-Lactamases