title: [Resistance to extended-spectrum cephalosporins in non-inducible AmpC enterobacteria: evaluation of the new MIC breakpoints].
abstract: The aims of this study were to evaluate the in vitro activity of extended-spectrum cephalosporins (ESC) in non-inducible AmpC enterobacteria throµgh phenotypic and genotypic characterization of the mechanisms of resistance (ESBL, plasmid-mediated AmpC and KPC) and to evaluate the interpretation criteria proposed by the existing recommendations and the new breakpoints established by the CLSI and the EUCAST. Susceptibility tests and PCR multiplex for b/aSHV and b/aCTX-M and amplification using specific primers was performed. One hundred sixty nine resistant isolates: K/ebsie//a pneumoniae (95), Escherichia co/i (55), and Proteus mirabi/is (19) were recovered. ESC resistance was 56.2 %, 32.6%, and 11.2 %, respectively. ESBL was detected in 152 (90 %) isolates, plasmid-mediated AmpC in 12 (7 %) and KPC in 5 (3 %). The CLSI 2009 recommendations and the breakpoints sµggested by the CLSI 2010 and the EUCAST for ceftriaxone were efficacious to detect ESBL, whereas the different breakpoints for ceftazidime presented discrepancies. The CLSI 2010 breakpoints only detected 55 % of the ESBL-producing isolates due to the endemic presence of CTX-M ESBLs in our country. Regarding the plasmid-mediated AmpC producers, the recommendations of the CLSI 2010 and the EUCAST 2010 proved to be more efficient than the old ones.
authors.affiliation: Laboratorio de Bacteriologí Clínica, Departmento de Bioquímica Clínica, Hospital de Clínicas José de San Martin, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina. marcelanastro@hotmail.com
authors.forename: Marcela
authors.initials: M
authors.lastname: Nastro
authors.forename: Luciana
authors.initials: L
authors.lastname: Montoto Piazza
authors.forename: Elsa
authors.initials: E
authors.lastname: Saposnik
authors.forename: Susana
authors.initials: S
authors.lastname: García
authors.forename: Claudia
authors.initials: C
authors.lastname: Barberis
authors.forename: Carlos
authors.initials: C
authors.lastname: Vay
authors.forename: Carlos H
authors.initials: CH
authors.lastname: Rodríguez
authors.forename: Angela
authors.initials: A
authors.lastname: Famiglietti
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D000077723:Cefepime; D002442:Ceftazidime / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests / Q000592:standards*; D011446:Prospective Studies; D011512:Proteus Infections / Q000382:microbiology; D011513:Proteus mirabilis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D012958:Societies, Scientific / Q000592:standards; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D029968:Escherichia coli Proteins; D002443:Ceftriaxone; D000077723:Cefepime; D002442:Ceftazidime; C048795:AmpC beta-lactamases; D001618:beta-Lactamases