Epidemiology and risk factors for infections due to AmpC Β-lactamase-producing Escherichia Coli

Vanesa Pascual, Gabriel Ortiz, Maria Simó, Noemí Alonso, Maria Consol Garcia, Mariona Xercavins, Alba Rivera, Maria Antonia Morera, Elisenda Miró, Elena Espejo, Ferran Navarro, Mercé Gurguí, Josefa Pérez, Mónica Rodríguez-Carballeira, Javier Garau, Esther Calbo

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14 Citations (Scopus)


© The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. Objectives: To describe the prevalence and risk factors for infection due to AmpC Β-lactamase-producing Escherichia coli (AmpC-EC). Methods: For the prevalence study, all clinical isolates of E. coli with reduced susceptibility to third-generation cephalosporins were prospectively included from June 2010 to November 2011. For risk factor analysis, a case-control study was conducted. Cases were patients with an infection due to AmpC-EC. Controls were patients infected with cephalosporin-susceptible E. coli, matched 1:2. Detection of bla AmpC genes was done with a multiplex AmpC-PCR, and hyperproduction of E. coli chromosomal blaAmpC by quantitative RT-PCR. Alteration of the blaAmpC promoter was studied by PCR and sequencing. Results:We identified 243 (1.1%) AmpC-EC strains out of 21563 clinical isolates. Three cases with strains carrying ESBLs, 18 strains that were considered due to colonization and 8 cases lost to clinical follow-up were excluded. Finally, 214 cases were included in the analysis. Ninety-one cases (42.5%) and 269 (62.8%) controls were strictly community acquired (P,0.001). Thirty-five (16.3%) cases and 186 controls (43.5%) did not have any identifiable risk factor (P,0.001). Among cases, 158 (73.8%) were found to harbour an acquired AmpC (73.4% CMY-2). Previous use of fluoroquinolones [OR 2.6 (95% CI 1.12-3.36); P1/40.008] was independently associated with AmpC-EC in the multivariate analysis. Conclusions: Prevalence of AmpC in E. coli remains low in our area. Plasmid acquisition (CMY type) represents the main mechanism of AmpC production. A high proportion of community-acquired isolates and patients with no identifiable risk factors were found. Previous use of fluoroquinolones was identified as a risk factor.
Original languageEnglish
Article numberdku468
Pages (from-to)899-904
JournalJournal of Antimicrobial Chemotherapy
Issue number3
Publication statusPublished - 1 Jan 2015


  • Ampc Β-lactamases
  • Cephalosporins resistance
  • E. coli


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