title: Epidemiology and risk factors for infections due to AmpC β-lactamase-producing Escherichia coli.
abstract: OBJECTIVE
  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 blaAmpC 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 21 563 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); P = 0.008] 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.
authors.affiliation: Hospital Universitari Mútua de Terrassa, Barcelona, Spain vanesapascual@hotmail.com.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Pascual
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Ortiz
authors.affiliation: Catlab, Barcelona, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Simó
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain Universitat Autònoma de Barcelona, Barcelona, Spain Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Noemí
authors.initials: N
authors.lastname: Alonso
authors.affiliation: Consorci Sanitari de Terrassa, Barcelona, Spain.
authors.forename: Maria Consol
authors.initials: MC
authors.lastname: Garcia
authors.affiliation: Catlab, Barcelona, Spain.
authors.forename: Mariona
authors.initials: M
authors.lastname: Xercavins
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Rivera
authors.affiliation: Catlab, Barcelona, Spain.
authors.forename: Maria Antonia
authors.initials: MA
authors.lastname: Morera
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Elisenda
authors.initials: E
authors.lastname: Miró
authors.affiliation: Consorci Sanitari de Terrassa, Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Espejo
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain Universitat Autònoma de Barcelona, Barcelona, Spain Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Ferran
authors.initials: F
authors.lastname: Navarro
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain Universitat Autònoma de Barcelona, Barcelona, Spain Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Mercè
authors.initials: M
authors.lastname: Gurguí
authors.affiliation: Catlab, Barcelona, Spain.
authors.forename: Josefa
authors.initials: J
authors.lastname: Pérez
authors.affiliation: Hospital Universitari Mútua de Terrassa, Barcelona, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Rodríguez-Carballeira
authors.affiliation: Hospital Universitari Mútua de Terrassa, Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Garau
authors.affiliation: Hospital Universitari Mútua de Terrassa, Barcelona, Spain Universitat Internacional de Catalunya, Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Calbo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: AmpC β-lactamases; E. coli; cephalosporins resistance